Understanding the Four Critical Boundaries

Arc flash protection is built upon a system of four distinct boundaries, each serving a specific protective function.

Limited Approach Boundary

The Limited Approach Boundary represents the distance from an energized component where
unqualified persons (those without proper electrical safety training) must not cross without escort. This
boundary serves as the outermost protective perimeter and is determined based on nominal system
voltage.
Unqualified individuals may only cross this boundary when they demonstrate a valid need and receive
continuous escort by qualified personnel. This first line of defense ensures that individuals without
proper training remain at a safe distance from potential electrical hazards.

Restricted Approach Boundary

The Restricted Approach Boundary establishes a more stringent protective zone that only qualified
electrical workers may enter. Within this boundary, specific PPE and insulated tools become
mandatory, and inadvertent movement must be prevented through proper work positioning. The risk of
electrical shock increases significantly due to proximity, and documented work permits are required
for any repair work inside this limit.

Arc Flash Boundary

Unlike the previous boundaries based on shock protection, the Arc Flash Boundary specifically
addresses thermal energy exposure. This critical boundary marks the distance at which
second-degree burns could occur during an arc flash incident. It requires determination through
incident energy calculations specific to each piece of equipment.
The Arc Flash Boundary may extend significantly farther than shock protection boundaries in certain
systems, sometimes reaching 20 feet or more for high-energy equipment. Anyone crossing this
threshold must wear appropriate arc-rated clothing and PPE matched to the estimated incident energy
levels.

Calculation Methodologies: Beyond the Simplified Tables

While NFPA 70E offers tables for estimating boundaries, comprehensive protection requires more
detailed calculation approaches.

Incident Energy Analysis Method

The incident energy analysis method applies IEEE 1584 calculation methodologies to determine
equipment-specific boundaries rather than relying on general categories. This engineering-based
approach accounts for system-specific factors including available fault current, protective device
clearing time, gap between conductors, working distance, system grounding configuration, and
enclosure type and size.
This method typically provides more precise PPE requirements and often reduces excessive PPE
compared to table methods. The calculations produce specific incident energy values measured in
calories per square centimeter (cal/cm²) at defined working distances, which directly correlate to PPE
arc ratings.
Organizations implementing this approach must maintain regular updates when system changes occur.
Modifications to electrical distribution systems, changes in protective device settings, or even routine
maintenance on circuit breakers can significantly alter arc flash boundaries, requiring recalculation and
relabeling.

Practical Implementation Strategies

Translating calculated boundaries into workplace practice requires systematic implementation
approaches that make abstract mathematical concepts visible and understandable in the field.

Equipment Labeling Systems

Effective labeling forms the cornerstone of boundary implementation. Equipment labels should clearly
display all relevant boundaries, indicate required PPE categories, and include incident energy values at
working distance. Consistency across the facility helps workers quickly recognize and interpret
boundary information regardless of which area they’re working in.
Advanced labeling systems incorporate color-coding for rapid recognition and may include QR codes
linking to detailed procedures for that specific equipment. Labels must include calculation dates for
verification and be constructed from materials capable of withstanding the environmental conditions
present in the installation location.

Temporary Boundary Marking

Maintenance and project work often require temporary boundary marking systems to create visible
reminders of invisible boundaries. Facilities typically deploy portable boundary tape stands at
calculated distances, with distinct colors representing different boundaries. Some organizations
implement digital projection systems for complex environments where traditional boundary marking
proves difficult.
Effective programs train workers on proper placement verification and create standardized boundary kit
contents available at job sites. Work permits should document actual boundary placement, particularly
in areas with overlapping boundaries from multiple energy sources.

Digital Boundary Management

Advanced organizations increasingly implement digital boundary tracking systems to enhance
traditional approaches. Mobile applications can display real-time boundary information specific to
equipment being serviced, while wearable technology can alert workers to boundary encroachment
before violations occur.
Some facilities utilize augmented reality displays showing boundaries in complex environments,
particularly useful in congested industrial settings. These systems often integrate with work order
management systems to ensure appropriate precautions appear automatically when work is scheduled
on specific equipment.

Training Methodologies for Boundary Awareness

Effective boundary training goes beyond concept explanation to develop practical application skills that
workers can implement in diverse field conditions.

Boundary Decision-Making Scenarios

Training should incorporate decision-making elements that reflect real-world complexity. Scenariobased exercises should present multiple boundaries requiring assessment, dynamic situations with
changing requirements, and emergency response protocols when boundaries are compromised.
Workers need clear understanding of authorization processes for boundary crossing and communication
protocols when working near boundaries. Documentation requirements for various boundary zones
should be practiced until they become second nature rather than burdensome administrative tasks.

Special Applications and Considerations

Certain situations require modified approaches to boundary management due to their unique challenges
or heightened risk profiles.

Complex Multi-Feed Equipment

Equipment with multiple power sources presents unique boundary management challenges. Safety
professionals must determine worst-case boundary scenarios accounting for all potential energy sources
and establish clear procedures for boundary hierarchy during partial de-energization.
Documentation systems must account for the complexity of these situations, with special labeling
requirements indicating multiple sources. Workers require specialized training on verification
procedures for all potential energy sources before boundaries can be modified or reduced.

Outdoor and Extreme Environments

Outdoor installations and extreme environments necessitate adaptations to standard boundary practices.
High-wind environments may require enhanced boundary marking methods, while wet or corrosive
atmospheres demand more durable marking solutions.
Extreme temperature environments affect both boundary implementation and PPE utilization. Cold
weather may require additional protective layers beneath arc-rated clothing, potentially affecting
movement and dexterity within restricted boundaries. Limited visibility conditions in outdoor settings
during night work or adverse weather require enhanced marking strategies to maintain boundary
awareness.

Continuous Process Environments

Facilities where shutdown is exceptionally costly require specialized boundary management
approaches. These organizations often implement remote monitoring and operation strategies to
minimize the need for boundary crossing during normal operations.
When boundaries must be crossed in these environments, enhanced PPE protocols and specialized
work practices help reduce risk while maintaining operational continuity. Many such facilities invest in
engineering controls specifically designed to reduce boundary zones, such as remote racking systems,
infrared viewing windows, and robotic inspection technologies.

Measuring Program Effectiveness

Evaluating boundary program effectiveness requires both leading and lagging indicators. Organizations
should track boundary procedure compliance rates, authorized versus unauthorized boundary crossings,
and worker competency assessment scores as leading indicators of program health.
Near-miss reporting related to boundary violations provides valuable insights for program
improvement, while PPE compliance verification at various boundaries helps identify potential training
gaps. Regular review of boundary documentation in work permits reveals how well theoretical
knowledge translates to field application.
Effective programs establish feedback mechanisms allowing qualified workers to suggest
improvements to boundary management systems based on field experience. This continuous
improvement approach recognizes that those working within the boundaries daily often develop the
most practical insights for enhancement.

Beyond Compliance to Culture

Effective arc flash boundary management extends beyond mere regulatory compliance, becoming
ingrained in organizational safety culture. By implementing comprehensive assessment protocols,
practical field applications, and engaging training methodologies, organizations transform abstract
calculations into tangible protection systems.
The most successful electrical safety programs recognize that boundaries represent more than
mathematical formulas or floor markings—they serve as critical decision points where worker
behavior, engineering controls, and administrative systems intersect to prevent catastrophic injuries.
Through proper implementation of these concepts, electrical workers can navigate hazardous
environments with the protection afforded by invisible but life-saving perimeters.

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What is Incident Energy?

Incident energy refers to the amount of thermal energy that is released at a certain distance from an arc flash event, which is a dangerous phenomenon involving a rapid release of energy due to an electrical arc traveling through the air. The energy released during an arc flash can cause severe burns, injuries, and even fatalities.

Incident Energy Rating: Calorie per Centimeter Squared (cal/cm²)

The incident energy rating is expressed in units of calorie per centimeter squared (cal/cm²). This unit measures the thermal energy that would be imparted on a surface at a specified distance from an arc flash. In simpler terms, the cal/cm² rating helps to quantify the potential severity of an arc flash.

The incident energy rating plays a vital role in determining the level of protection required for electrical workers, as it helps to identify the appropriate personal protective equipment (PPE) needed to safeguard against the hazards of an arc flash.
The Role of Incident Energy Rating in Electrical Safety

• 1. Arc Flash Hazard Analysis: To establish a safe working environment, an arc flash hazard analysis is performed to evaluate the potential risk of an arc flash event. This analysis includes calculating the incident energy rating, which is a crucial factor in determining appropriate safety measures and PPE for electrical workers.
• 2. Selecting Personal Protective Equipment (PPE): PPE is designed to provide varying levels of protection, which are classified based on the cal/cm² rating. The National Fire Protection Association (NFPA) 70E standard outlines specific guidelines for selecting PPE based on the incident energy rating. By identifying the correct level of protection, electrical workers can minimize the risk of severe injuries during an arc flash event.
• 3. Safety Training and Awareness: Understanding the incident energy rating and its implications for electrical safety is essential for electrical workers, as it helps them recognize potential hazards and adopt the necessary precautions. Regular training and awareness programs can ensure that workers are familiar with the concept of incident energy, its rating, and the importance of adhering to safety standards.
• 4. Preventive Measures: By calculating the incident energy rating, facilities can identify high-risk areas and implement preventive measures to reduce the likelihood of an arc flash event. These measures may include updating electrical equipment, de-energizing circuits before work is performed, and maintaining a safe distance from live electrical components.

The incident energy rating in cal/cm² plays a crucial role in ensuring the safety of electrical workers by quantifying the potential severity of an arc flash event. By understanding this concept and adhering to electrical safety standards, workers can minimize the risk of injuries, while employers can create a safer working environment. Regular training, appropriate PPE selection, and the implementation of preventive measures all contribute to mitigating the hazards associated with arc flash events.

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Ground Fault Circuit Interrupters (GFCIs) are an essential component of electrical safety in modern homes and workplaces. These devices are designed to protect against electrical shock hazards by quickly disconnecting the power supply in the event of a ground fault. In this article, we will explore how GFCIs work, their benefits, and tips for their proper installation and maintenance, as well as the history of their development and their role in various applications.

History of GFCIs

The concept of the GFCI can be traced back to the 1960s when electrical engineer Charles Dalziel began researching ways to protect against electrical shock. His findings led to the development of the first GFCI, which was patented in 1965. Since then, GFCI technology has evolved and become a standard safety feature in electrical systems around the world.

How GFCIs Work

GFCIs function by continuously monitoring the electrical current flowing through a circuit. If there is an imbalance between the current flowing in the hot and neutral wires, it indicates a ground fault. This usually means that electricity is escaping the circuit and could potentially cause harm to people or property. In response, the GFCI trips and quickly disconnects the power supply, reducing the risk of electrical shock and fire.

Benefits of GFCIs

• 1. Protection against electrical shock: By promptly cutting off power in the event of a ground fault, GFCIs significantly reduce the risk of electrical shock, which can cause serious injury or even death.
• 2. Fire prevention: Ground faults can lead to electrical fires due to overheating and sparking. GFCIs help prevent these fires by quickly disconnecting the power supply when a ground fault is detected.
• 3. Protection for appliances: GFCIs can prevent damage to electrical appliances and devices connected to the circuit by minimizing exposure to ground faults.
• 4. Compliance with electrical codes: The installation of GFCIs is required by electrical codes in many countries, ensuring a baseline level of safety in residential and commercial settings.

GFCIs in Various Applications

GFCIs are not just limited to protecting residential and commercial buildings. They also play a crucial role in various applications, such as:

• 1. Construction sites: GFCIs are required on construction sites to protect workers from electrical hazards when using power tools and temporary power sources.
• 2. Outdoor events: Temporary power setups for outdoor events, such as festivals or concerts, should include GFCIs to protect attendees and equipment from potential electrical hazards.
• 3. Marinas and boat docks: The installation of GFCIs in marinas and boat docks can help prevent electrical shock hazards related to water, corrosion, and equipment malfunctions.

Proper Installation and Maintenance

• 1. Installation: GFCIs should be installed by a qualified electrician in accordance with local electrical codes. They are commonly installed in areas where there is a high risk of electrical shock, such as bathrooms, kitchens, garages, and outdoor receptacles.
• 2. Testing: Regularly test your GFCIs to ensure they are functioning correctly. Press the “test” button on the device, and if the GFCI trips, it is working properly. Reset the GFCI by pressing the “reset” button.
• 3. Maintenance: Replace any faulty GFCIs immediately, and consult an electrician if you encounter any problems or concerns with your GFCI devices. Periodically inspect GFCI outlets for signs of wear, damage, or corrosion, and have them replaced if necessary.
• 4. Upgrades: As GFCI technology continues to evolve, consider upgrading older GFCI devices to newer models that offer improved performance and additional safety features, such as tamper-resistant outlets or self-testing capabilities.
• 5. Educate others: Spread awareness of the importance of GFCIs and electrical safety by educating family members, coworkers, and friends about the proper use and maintenance of these devices.

GFCIs play a crucial role in electrical safety by protecting against electrical shock hazards and fires. They have become a standard safety feature in electrical systems around the world, thanks to the pioneering work of researchers like Charles Dalziel. Ensure your home or workplace is equipped with properly installed and maintained GFCIs to minimize the risks associated with ground faults. By staying informed and vigilant, we can all contribute to a safer environment when it comes to electricity use.

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Transcription:

Hi. I want to talk today about electrical enclosures and the space in front of those.

It’s important that we keep those clear with depth of at least 36 inches and the width of the panel that could be opened up.

The reason this is, and this is a contentious thing in every plant I ever worked, plants I visit all the time. This is always a problem. Operations people want to stack stuff in front of the panels, park a fork truck, a pallet, stack some boxes, those kinds of things. To a lot of people, it doesn’t seem like that big of a deal. “Maintenance department’s always complaining we put stuff in front of the panels” and what have you.

Well, it’s not just for the convenience of the maintenance people to get into the panels. Okay, yeah, some of it’s that. But the most important thing is that sometimes a maintenance person, electrical person needs access to electrical panel to shut it off in case of emergency. Maybe someone’s in the process of being electrocuted, being shocked really badly, going to be injured. If we don’t get the panel disconnected quickly, if we can’t access the panel, we can’t open it quickly, we can’t get in front of it because there’s a fork truck or a pallet or a bunch of boxes, we don’t even see it, then that’s a problem.

I worked in a plant one time that had a fire. There was a really old DC drive. This thing had to be from the ’60s. It was just really old and we all knew it needed replaced, but kept babying it. One day, it caught fire, just started smoking and it was getting really bad. If we couldn’t have gotten access to that disconnect to shut that thing off, the fire would’ve gotten a lot worse and could’ve spread to other equipment, possibly destroyed other equipment or injured somebody. So there are times where we need access to an electrical panel.

Probably one of the worst cases I ever saw of a panel being hidden or no access to it is I worked at a plant that was built in the ’40s and we couldn’t find this panel. We knew it had to be there someplace because it was feeding a lot of stuff, but we couldn’t find it. One of the old-timers kind of turned us on to where it was because we would’ve never looked there. It was in the division vice president’s office behind his desk, behind a painting. Yeah, behind a painting. So if it hadn’t been for that guy had been working there for 40 years, we didn’t never known where that panel was.

That’s a dumb place to put a panel, but probably over the years since the ’40s when that plant was built, you know how things change. That office probably was not an office in the ’40s. It was something else. But now it’s an office and we got to hide the panel. The vice president didn’t like the looks of the panel evidently and he didn’t want to hear anything from us about how that’s not right. So it’s probably still that way today would be my guess.

I was recently in an automotive parts plant where they had lots and lots of CNC machining centers and it was important that they, of course, get as many of those machines in there as they can. But what ended up happening is the machines were set too closely to be able to safely work in the electrical panels that were behind the machines. It looked very similar to this photograph here. This is not the actual plant, but very similar situation. You can see all of the CNC machining centers. Then these two are so close and you see that control panel there.

Well, the situation was at this plant to work on that control panel, you had to walk back there between those two machines and you couldn’t gain access from the other end. The other end was closed off by conveyors and stuff, so you couldn’t get there that way. You had to access at this direction. You actually had to walk past the control panel and then open it to be able to work on it. But when you opened it, it wouldn’t actually open 100% of the way, wouldn’t open up to even 90 degrees, so that added a problem. There were stuff on the panel or what have you. That panel door needed to be opened all the way.

Here’s the other bigger problem with that. The panel door wouldn’t fully open because it hit the other machine, the one next to it, right? There’s this protrusion on that machine so when you open the door, it hit that. So you think about this. You had to walk past the control panel, open the door, which then hit the other machine. So in an emergency, you couldn’t run that direction because the panel door had that whole area between the two machines closed off.

Now picture this. If you, gosh, I hope this never happens to you, but if you’re in an arc flash event, two things likely will happen. You will be deafened by the loud sound and you’ll be blinded by the bright light. Now picture yourself back in there between these two machines and an arc flash occurs and you get blinded and deafened, how are you going to get out of there? You may realize what direction you need to go to get down to there and things may still be on fire, but you can’t. You run into that panel that is open and stuck, hitting the protrusion on the other machine. So how are you going to get out of there?

I understand we have to put machines close together, that’ll never change. I mean this production, right? But what can you do to fix that? One suggestion that we came up with for that particular machine was, instead of having the control panel door in one piece, make it in two pieces. It opened up like French doors would, rather than just one piece. Because if that was the case they would both open up, there would be enough.

So we just got to come up with easy ways to figure out how to get our control panels opened, all electrical enclosures fully opened and not damaged and have access in and out of it because we need access to maybe quickly turn something off. We need to be able to get out of there in case there’s a problem and we’re blinded and deafened by the arc flash event.

If you’re a safety professional and it’s your job to keep people from stacking stuff in front of electrical enclosures, maybe this gives you a little bit of ammunition that you can use to convince people that there’s a real reason why we don’t want stuff in front of there. And it’s not just because we maintenance people want to easily access it and conveniently get to the equipment.

There’s a reason we need to, and it’s not just convenience. It’s safety. We need to turn panels off in an emergency. If there is an emergency, an arc flash or something, we need to be able to get out of there. This is one of those OSHA things that should an OSHA inspector come in, these are things that are easy to spot and cost you some money. More importantly than costing the company money is safety. We need access to those panels. We need to be able to get in there and get out of there in case of an emergency, so it’s really important. It’s really important.

I hope this video helped you today so visit our website, electricaltrainingpro.com. Look at other videos that we have there. Suggest videos that you would like to see. My email address is on the screen, so feel free to drop me a line and ask me anything you would like. I answer questions all the time. Thank you and have a good day.

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Video Transcript

Let’s talk about arc flash labels. As I travel around the country teaching 70E classes, refresher and awareness classes and what have you, I see a lot of confusion about when the labels need to go on, what needs to be on them, what can’t be on them, things like that. So let’s talk about that.

First. The owner of the equipment is responsible for the label. Now, that’s very simple if you are a manufacturer, own the building you’re in and you own all the equipment in the building, distribution as well as production equipment, that’s very simple. You own all that stuff. Where it gets a little more complicated is in multi-use buildings where maybe it’s several floors of a building, different companies own different floors. There’s a building in Chicago that I know of that gets a little more complicated. Multi-floors, the building is owned by a real estate investment trust, it’s run by a property management company who employs another company who takes care of all the maintenance, several floors of that building are inhabited by companies that have their own maintenance people, there’s three floors that are a data center for a cell phone company, so they have their own maintenance people. Who owns what equipment and who is responsible for those labels gets a little more complicated. Different people have different motivations for wanting to get those labels on.

So the owner of the equipment, 70E says, is responsible for that label. Now what has to be on that label; obviously nominal voltage has to be on there, the arc flash boundary has to be on there and at least one of the following, and this is where it gets a little more complicated.

(a) Is available incident energy and the corresponding work distance or the arc flash PPE category but not both. So you can have incident energy or the PPE category but not both. And that’s where a lot of people stumble there. I used to own a company that did hundreds of arc flash studies across the nation and it was typical back several years ago where we would put incident energy and the PPE category on the same label. Well, starting in 2015, it stopped being allowed. You can’t have incident energy and the PPE category on the same label.

(b) Another thing that you can have on label is minimum arc rating of clothing. Let’s say that your company has done an arc flash study and has found most of your equipment is say anywhere between two calories and nine calories, so maybe you come up with a label that just says minimum arc rating on all this equipment is 10 or 11 or something like that and then you mark all of it accordingly. It makes it a little bit simpler.

(c) Another thing that you can do is site specific level of PPE that would be a level that you create yourself like say A, B or C and you train all of your maintenance folks what A is and what B is and then from that they know what to wear.

The data on the label has to be reviewed every five years. Now, that doesn’t mean you have to have a complete new arc flash assessment done every five years. It means that you need to review what the utility data is to make sure the utility data is correct and utility’s not built a great big new substation that feed your equipment, that you’ve changed nothing. And I’ve never worked at a facility where you’ve never changed anything over five years, so that’s kind of a rarity in my experience, anyway.

So you would have to confirm and review and make sure that nothing’s changed and if nothing’s changed you don’t need to do a complete new study, but if things have changed in your distribution equipment or in your utility, then you need to redo the study.

Christopher Coache works for National Fire Protection Association and put together the handbook for electrical safety in the workplace. This is the 70E hand book, it’s a companion book that goes with 70E. I highly recommend that everyone reads this, I have it in an e-book, and I read it all the time, just wonderful stuff in there. It’s got everything that 70E has, but then explains in more detail of how we got there, what these things mean and how you could incorporate that. And I don’t like slides with a lot of words on them but these are good words on this particular slide, the employees should not be expected to calculate the incident energy value or to determine whether a job complies with the arc flash PPE category.

So it’s not the employee’s responsibility to figure out what the incident energy rating of that piece of equipment is. It’s not the employee’s job to figure out what the category rating of that equipment is, it’s the employer’s responsibility. The employee needs to know how to read that label to determine what PPE to wear. It’s on the employer to figure out what that arc rating is or incident energy rating is. It’s on the employer to figure out what should be on that label, not the employee. So 70E says that equipment has to have an arc flash label. A lot of people take that to mean that, and it has for years, and people have taken it to mean this, that you do an arc flash assessment, you do an incident energy analysis, then you get your labels. Well, you need to have labels even if you’ve not had that done, even if you don’t intend to ever have that done. You still need labels so you have to put labels on even for the category method. Because there are things that have to be evaluated to use the category method and have to be evaluated by engineers.

There are maximum fault clearing times and maximum fault current allowance on the PPE tables. For years we’ve ignored those, a lot of people but we can’t now, we have to have someone calculate those to make sure that we’re within the parameters that allow us to use the tables. This is where a lot of people over the years have had to skip this because they just didn’t have this done. But you need to have this done. The National Electric Code now requires that you have maximum available fault current labeled on your service equipment. So we need to get this done. So anyway, Christopher Coache, I’m a big fan, he’s got a blog, makes videos, very good information NFPA, his website NFPA xchange recommend that highly a lot of good interpretive stuff, things I’ve learned from this guy. This is good stuff right here.

What needs labeled. Well, equipment that while energized is gonna require servicing or maintenance or adjusting or inspection. So what is that? Is it a motor? Three-phase motor connection box? No. We don’t open those up while it’s energized, generally we don’t, so we don’t need to label those so, but a disconnect, yeah, we have to open those while they’re energized to verify they’re not energized. We gotta do… At disconnects, we have to verify zero volts at the disconnects, and so when we open up that disconnect to verify it’s turned off we still have to treat it as it’s on, as it’s energized so it gets a label.

What about in this photograph, circuit breaker panel boards? Yeah, those need labels because we’re gonna open those and verify the energization. Those are things we open up while energized sometimes. What about that transformer on the floor? No, no, we don’t open those up to work on those. It’s important that the equipment that while energized is gonna be serviced or maintained gets a label. Raceways, condolets, pull boxes, those kind of things don’t, they won’t need a label, ’cause we don’t open those while they’re energized and if we do there’s insulated conductors in there, so. Things that while energized require service, maintenance, inspection need to have a label.

Now, so when it comes to arc flash labels the owner is responsible for it, you can have incident energy or the PPE category you can’t have both, the labels go on equipment that’s gonna be serviced or maintained while energized. The employee should not be expected to go out and calculate the incident energy for a particular panel and put that label on, the employees should not be expected to go out and figure if they can use the PPE category tables. This is things that have to be done by the employer, it’s the employer’s responsibility, and it needs done prior to the maintenance person going out and working on that equipment.

I hope this video helps to clear up some of those issues that I see out there, so make sure we get our labels in compliance, and get those things done. If you have any other questions, there’s the contacts in the link below, please don’t hesitate to give me a call, drop me a line and I’ll answer any kind of questions you got. Thank you very much.

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If you had to give an elevator pitch for electrical safety, the kind of pitches that sales people make all the time,  what is that thing that you would tell the prospective client before the elevator ride ends to sell them on your product or service? This is my elevator pitch for electrical safety. A client or somebody asks what do we have to do in our company, to comply? It’s pretty simple and if you boil it down to its smallest fundamentals, the elevator pitch would be each employee has to be qualified for the electrical task they are performing and/or the electrical hazard that they are exposed to. This applies to unqualified people as well; even though an unqualified person won’t necessarily be doing electrical tasks, they are going to be exposed to electrical hazards. Hazards like from extension cords to working around or in the vicinity of qualified people opening cabinets. So they’re going to be exposed, so they have to be trained for that exposure, whatever it is.

So saying each worker has to be qualified for the tasks that they’re performing, under the word “qualified” comes 1,000 things. It comes knowing the training, knowing the equipment, being trained on the safety of that equipment and that exposure, the voltage, the arc flash potential. It includes knowing the proper PPE to wear, the proper tools to use, being able to understand the equipment, the operation, construction and operation of that equipment. So there’s a lot to it, there’s a lot more that goes into it.

So simply put, each employee has to be qualified, which means trained, can demonstrate that they know what you’re doing on the electrical task they are performing and the electrical hazard they are exposed to. That’s the minimum, that’s where you gotta start. So if you’re in charge of safety at your facility, if you’re a plant manager or whatever your job is, how would you answer that question? Are your people qualified for the task and the hazard. A simple question put as an elevator pitch.

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Critical Electrical Safety Targets

Make sure these get done!

• De-energize. Unless the employer can justify live work, it is not permitted. Live testing and troubleshooting are allowed, but altering the circuit live is difficult to justify.
• Workers must be qualified for each electrical task they perform, and the electrical hazard they are exposed to.
• Workers must know how to perform a risk assessment, and how to reduce the associated risk.
• A worker must have access to and utilize the appropriate PPE for the electrical hazard.
• Employers need to ensure the worker has access to arc-rated PPE throughout the range of incident energy indicated by their incident energy analysis.
• Test-Before-Touch. A qualified worker must verify zero energy before contacting de-energized parts by performing the Live-Dead-Live test.
• While verifying zero energy, the qualified worker must utilize appropriate PPE and insulated tools.
• All PPE, as well as all tools and equipment with electrical insulation, must be inspected daily before each use.
• The owner of the electrical equipment is responsible for providing labels that include nominal voltage, arc flash boundary, and a method of determining the appropriate arc flash  PPE to be worn.
• Rubber insulated gloves must be electrically tested every six months.
• Arc-rated clothing and insulated gloves must fit the user, and provide full coverage.

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Limitations Of Live Electrical Work

First, let’s begin with the limitations of live electrical work. Hopefully, the only live work your people are performing is verification of zero volts during lockout/tagout and maybe some troubleshooting and other diagnostic work. Repair of electrical circuits, that is replacing of components or altering the circuit in any way, should not be done live. OSHA and 70E have requirements which limit, and in most cases forbid this work. But, that’s a subject for another article. A qualified electrical worker must verify zero volts during lockout tagout, and that’s live work.

Am I A Qualified Electrician?

In my opinion, it takes years to become a qualified electrician or electrical worker who can safely work on and around energized equipment. You have to have received training on and possess a demonstrable knowledge of the electrical equipment installations, operation, construction, as well as the hazards involved and how to reduce the risk. As an example, if an electrician is knowledgeable about the equipment, but has never been trained on the required safety procedures, PPE or risk assessments; they can’t be considered qualified. On the flip said, if a worker is knowledgeable about the safety procedures but not the equipment; they can’t be considered qualified either. To be considered qualified, you have to know the equipment and know the safe way to work on the equipment. It takes years to accomplish this, and the training should never end because technology and safety standards continue to advance. OSHA and NFPA 70E have a list of training topics and skills for qualified electrical workers that you can use a checklist to see where you are.

Only The Employer Can Designate A Worker As Qualified

There is no blanket certification program you can send your people to that can designate them qualified. Only the employer can designate them as qualified. The only thing an outside training organization can do is provide the training that the worker must have before the employer should consider them qualified.

Who Needs To Be Qualified?

Regardless of job classification, any worker who is exposed to live electrical hazards must be qualified to work safely around that hazard. That includes electricians, electrical and electronic repair techs, multi-craft maintenance workers, assembly workers building and testing electrical equipment, and engineers of various disciplines.

A worker can become qualified on some tasks and not others. Some of my clients train equipment operators to operate the disconnects for their machines. Although they are not exposed to shock hazards, because the disconnects aren’t opened, they are trained on the arc flash hazard which could occur when operating a large disconnect. They are trained on those tasks to disconnect their equipment safely. This does not make them a qualified electrical worker ready to join the maintenance department. But it does make them a qualified worker on their narrow set of tasks.

Documentation

Your company needs to have a documented list of which employees are qualified for what tasks and have a checklist of what that individual qualification requires them to be trained on and demonstrate to you they can safely do it. If OSHA or a corporate safety auditor visits your facility and witnesses an employee doing live work, their first questions will include, is that worker qualified for that task and can I see your documentation.

Conclusion

All workers who are exposed to electrical hazards must be trained for that exposure and task. The training should never end as standards and technology continue to advance. Only the employer can designate someone qualified. OSHA and 70E have a checklist of topics and skills a qualified electrical worker must be proficient at and trained on. Here at Electrical Training Pro we offer training for both Qualified Workers as described above, and Unqualified Workers who may be in the vicinity of live work.

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Based on the number of questions I get from clients, the electrical safety-related OSHA training requirements can be confusing. In simple terms, a company has to provide electrical safety-related work practices and train employees on them. A worker has to be qualified, trained and can demonstrate skills, on any task they are to perform when exposed to electrical hazards. How much training is required? Enough to accomplish that.

Below in OSHA’s words:

1910.332

1910.332(a)
Scope. The training requirements contained in this section apply to employees who face a risk of electric shock that is not reduced to a safe level by the electrical installation requirements of 1910.303 through 1910.308.

Note: Employees in occupations listed in Table S-4 face such a risk and are required to be trained. Other employees who also may reasonably be expected to face comparable risk of injury due to electric shock or other electrical hazards must also be trained.
1910.332(b)
Content of training.
1910.332(b)(1)
Practices addressed in this standard. Employees shall be trained in and familiar with the safety-related work practices required by 1910.331 through 1910.335 that pertain to their respective job assignments.
1910.332(b)(2)
Additional requirements for unqualified persons. Employees who are covered by paragraph (a) of this section but who are not qualified persons shall also be trained in and familiar with any electrically related safety practices not specifically addressed by 1910.331 through 1910.335 but which are necessary for their safety.
1910.332(b)(3)
Additional requirements for qualified persons. Qualified persons (i.e. those permitted to work on or near exposed energized parts) shall, at a minimum, be trained in and familiar with the following:
1910.332(b)(3)(i)
The skills and techniques necessary to distinguish exposed live parts from other parts of electric equipment.
1910.332(b)(3)(ii)
The skills and techniques necessary to determine the nominal voltage of exposed live parts, and
1910.332(b)(3)(iii)
The clearance distances specified in 1910.333(c) and the corresponding voltages to which the qualified person will be exposed.

Note 1: For the purposes of 1910.331 through 1910.335, a person must have the training required by paragraph (b)(3) of this section in order to be considered a qualified person.

Note 2: Qualified persons whose work on energized equipment involves either direct contact or contact by means of tools or materials must also have the training needed to meet 1910.333(C)(2).
1910.332(c)
Type of training. The training required by this section shall be of the classroom or on-the-job type. The degree of training provided shall be determined by the risk to the employee.

1910.333

1910.333(a)
“General.” Safety-related work practices shall be employed to prevent electric shock or other injuries resulting from either direct or indirect electrical contacts, when work is performed near or on equipment or circuits which are or may be energized. The specific safety-related work practices shall be consistent with the nature and extent of the associated electrical hazards.
1910.333(a)(1)
“Deenergized parts.” Live parts to which an employee may be exposed shall be deenergized before the employee works on or near them, unless the employer can demonstrate that deenergizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations. Live parts that operate at less than 50 volts to ground need not be deenergized if there will be no increased exposure to electrical burns or to explosion due to electric arcs.
Note 1: Examples of increased or additional hazards include interruption of life support equipment, deactivation of emergency alarm systems, shutdown of hazardous location ventilation equipment, or removal of illumination for an area.
Note 2: Examples of work that may be performed on or near energized circuit parts because of infeasibility due to equipment design or operational limitations include testing of electric circuits that can only be performed with the circuit energized and work on circuits that form an integral part of a continuous industrial process in a chemical plant that would otherwise need to be completely shut down in order to permit work on one circuit or piece of equipment.
Note 3: Work on or near deenergized parts is covered by paragraph (b) of this section.
..1910.333(a)(2)
1910.333(a)(2)
“Energized parts.” If the exposed live parts are not deenergized (i.e., for reasons of increased or additional hazards or infeasibility), other safety-related work practices shall be used to protect employees who may be exposed to the electrical hazards involved. Such work practices shall protect employees against contact with energized circuit parts directly with any part of their body or indirectly through some other conductive object. The work practices that are used shall be suitable for the conditions under which the work is to be performed and for the voltage level of the exposed electric conductors or circuit parts. Specific work practice requirements are detailed in paragraph (c) of this section.
1910.333(b)
“Working on or near exposed deenergized parts.”
1910.333(b)(1)
“Application.” This paragraph applies to work on exposed deenergized parts or near enough to them to expose the employee to any electrical hazard they present. Conductors and parts of electric equipment that have been deenergized but have not been locked out or tagged in accordance with paragraph (b) of this section shall be treated as energized parts, and paragraph (c) of this section applies to work on or near them.
1910.333(b)(2)
“Lockout and Tagging.” While any employee is exposed to contact with parts of fixed electric equipment or circuits which have been deenergized, the circuits energizing the parts shall be locked out or tagged or both in accordance with the requirements of this paragraph. The requirements shall be followed in the order in which they are presented (i.e., paragraph (b)(2)(i) first, then paragraph (b)(2)(ii), etc.).
Note 1: As used in this section, fixed equipment refers to equipment fastened in place or connected by permanent wiring methods.
Note 2: Lockout and tagging procedures that comply with paragraphs (c) through (f) of 1910.147 will also be deemed to comply with paragraph (b)(2) of this section provided that:
[1] The procedures address the electrical safety hazards covered by this Subpart; and
[2] The procedures also incorporate the requirements of paragraphs (b)(2)(iii)(D) and (b)(2)(iv)(B) of this section.
1910.333(b)(2)(i)

Checkout Our Practical Guide To Arc Flash And NFPA 70E

“Procedures.” The employer shall maintain a written copy of the procedures outlined in paragraph (b)(2) and shall make it available for inspection by employees and by the Assistant Secretary of Labor and his or her authorized representatives.
Note: The written procedures may be in the form of a copy of paragraph (b) of this section.
..1910.333(b)(2)(ii)
1910.333(b)(2)(ii)
“Deenergizing equipment.”
1910.333(b)(2)(ii)(A)
Safe procedures for deenergizing circuits and equipment shall be determined before circuits or equipment are deenergized.
1910.333(b)(2)(ii)(B)
The circuits and equipment to be worked on shall be disconnected from all electric energy sources. Control circuit devices, such as push buttons, selector switches, and interlocks, may not be used as the sole means for deenergizing circuits or equipment. Interlocks for electric equipment may not be used as a substitute for lockout and tagging procedures.
1910.333(b)(2)(ii)(C)
Stored electric energy which might endanger personnel shall be released. Capacitors shall be discharged and high capacitance elements shall be short-circuited and grounded, if the stored electric energy might endanger personnel.
Note: If the capacitors or associated equipment are handled in meeting this requirement, they shall be treated as energized.
1910.333(b)(2)(ii)(D)
Stored non-electrical energy in devices that could reenergize electric circuit parts shall be blocked or relieved to the extent that the circuit parts could not be accidentally energized by the device.
1910.333(b)(2)(iii)
“Application of locks and tags.”
1910.333(b)(2)(iii)(A)
A lock and a tag shall be placed on each disconnecting means used to deenergize circuits and equipment on which work is to be performed, except as provided in paragraphs (b)(2)(iii)(C) and (b)(2)(iii)(E) of this section. The lock shall be attached so as to prevent persons from operating the disconnecting means unless they resort to undue force or the use of tools.
..1910.333(b)(2)(iii)(B)
1910.333(b)(2)(iii)(B)
Each tag shall contain a statement prohibiting unauthorized operation of the disconnecting means and removal of the tag.
1910.333(b)(2)(iii)(C)
If a lock cannot be applied, or if the employer can demonstrate that tagging procedures will provide a level of safety equivalent to that obtained by the use of a lock, a tag may be used without a lock.
1910.333(b)(2)(iii)(D)
A tag used without a lock, as permitted by paragraph (b)(2)(iii)(C) of this section, shall be supplemented by at least one additional safety measure that provides a level of safety equivalent to that obtained by use of a lock. Examples of additional safety measures include the removal of an isolating circuit element, blocking of a controlling switch, or opening of an extra disconnecting device.
1910.333(b)(2)(iii)(E)
A lock may be placed without a tag only under the following conditions:
1910.333(b)(2)(iii)(E)(1)
Only one circuit or piece of equipment is deenergized, and
1910.333(b)(2)(iii)(E)(2)
The lockout period does not extend beyond the work shift, and
1910.333(b)(2)(iii)(E)(3)
Employees exposed to the hazards associated with reenergizing the circuit or equipment are familiar with this procedure.
..1910.333(b)(2)(iv)
1910.333(b)(2)(iv)
Verification of deenergized condition. The requirements of this paragraph shall be met before any circuits or equipment can be considered and worked as deenergized.
1910.333(b)(2)(iv)(A)
A qualified person shall operate the equipment operating controls or otherwise verify that the equipment cannot be restarted.
1910.333(b)(2)(iv)(B)
A qualified person shall use test equipment to test the circuit elements and electrical parts of equipment to which employees will be exposed and shall verify that the circuit elements and equipment parts are deenergized. The test shall also determine if any energized condition exists as a result of inadvertently induced voltage or unrelated voltage backfeed even though specific parts of the circuit have been deenergized and presumed to be safe. If the circuit to be tested is over 600 volts, nominal, the test equipment shall be checked for proper operation immediately after this test.
1910.333(b)(2)(v)
“Reenergizing equipment.” These requirements shall be met, in the order given, before circuits or equipment are reenergized, even temporarily.
1910.333(b)(2)(v)(A)
A qualified person shall conduct tests and visual inspections, as necessary, to verify that all tools, electrical jumpers, shorts, grounds, and other such devices have been removed, so that the circuits and equipment can be safely energized.
..1910.333(b)(2)(v)(B)
1910.333(b)(2)(v)(B)
Employees exposed to the hazards associated with reenergizing the circuit or equipment shall be warned to stay clear of circuits and equipment.
1910.333(b)(2)(v)(C)
Each lock and tag shall be removed by the employee who applied it or under his or her direct supervision. However, if this employee is absent from the workplace, then the lock or tag may be removed by a qualified person designated to perform this task provided that:
1910.333(b)(2)(v)(C)(1)
The employer ensures that the employee who applied the lock or tag is not available at the workplace, and
1910.333(b)(2)(v)(C)(2)
The employer ensures that the employee is aware that the lock or tag has been removed before he or she resumes work at that workplace.
1910.333(b)(2)(v)(D)
There shall be a visual determination that all employees are clear of the circuits and equipment.
1910.333(c)
“Working on or near exposed energized parts.”
1910.333(c)(1)
“Application.” This paragraph applies to work performed on exposed live parts (involving either direct contact or by means of tools or materials) or near enough to them for employees to be exposed to any hazard they present.
..1910.333(c)(2)
1910.333(c)(2)
“Work on energized equipment.” Only qualified persons may work on electric circuit parts or equipment that have not been deenergized under the procedures of paragraph (b) of this section. Such persons shall be capable of working safely on energized circuits and shall be familiar with the proper use of special precautionary techniques, personal protective equipment, insulating and shielding materials, and insulated tools.
1910.333(c)(3)
“Overhead lines.” if work is to be performed near overhead lines, the lines shall be deenergized and grounded, or other protective measures shall be provided before work is started. If the lines are to be deenergized, arrangements shall be made with the person or organization that operates or controls the electric circuits involved to deenergize and ground them. If protective measures, such as guarding, isolating, or insulating, are provided, these precautions shall prevent employees from contacting such lines directly with any part of their body or indirectly through conductive materials, tools, or equipment.
Note: The work practices used by qualified persons installing insulating devices on overhead power transmission or distribution lines are covered by 1910.269 of this Part, not by 1910.332 through 1910.335 of this Part. Under paragraph (c)(2) of this section, unqualified persons are prohibited from performing this type of work.
1910.333(c)(3)(i)
“Unqualified persons.”
1910.333(c)(3)(i)(A)
When an unqualified person is working in an elevated position near overhead lines, the location shall be such that the person and the longest conductive object he or she may contact cannot come closer to any unguarded, energized overhead line than the following distances:
1910.333(c)(3)(i)(A)(1)
For voltages to ground 50kV or below – 10 feet (305 cm);
1910.333(c)(3)(i)(A)(2)
For voltages to ground over 50kV – 10 feet (305 cm) plus 4 inches (10 cm) for every 10kV over 50kV.
..1910.333(c)(3)(i)(B)
1910.333(c)(3)(i)(B)
When an unqualified person is working on the ground in the vicinity of overhead lines, the person may not bring any conductive object closer to unguarded, energized overhead lines than the distances given in paragraph (c)(3)(i)(A) of this section.
Note: For voltages normally encountered with overhead power line, objects which do not have an insulating rating for the voltage involved are considered to be conductive.
1910.333(c)(3)(ii)
“Qualified persons.” When a qualified person is working in the vicinity of overhead lines, whether in an elevated position or on the ground, the person may not approach or take any conductive object without an approved insulating handle closer to exposed energized parts than shown in Table S-5 unless:
1910.333(c)(3)(ii)(A)
The person is insulated from the energized part (gloves, with sleeves if necessary, rated for the voltage involved are considered to be insulation of the person from the energized part on which work is performed), or
1910.333(c)(3)(ii)(B)
The energized part is insulated both from all other conductive objects at a different potential and from the person, or
1910.333(c)(3)(ii)(C)
The person is insulated from all conductive objects at a potential different from that of the energized part.

..1910.333(c)(3)(iii)
1910.333(c)(3)(iii)
“Vehicular and mechanical equipment.”
1910.333(c)(3)(iii)(A)
Any vehicle or mechanical equipment capable of having parts of its structure elevated near energized overhead lines shall be operated so that a clearance of 10 ft. (305 cm) is maintained. If the voltage is higher than 50kV, the clearance shall be increased 4 in. (10 cm) for every 10kV over that voltage. However, under any of the following conditions, the clearance may be reduced:
1910.333(c)(3)(iii)(A)(1)
If the vehicle is in transit with its structure lowered, the clearance may be reduced to 4 ft. (122 cm). If the voltage is higher than 50kV, the clearance shall be increased 4 in. (10 cm) for every 10 kV over that voltage.
1910.333(c)(3)(iii)(A)(2)
If insulating barriers are installed to prevent contact with the lines, and if the barriers are rated for the voltage of the line being guarded and are not a part of or an attachment to the vehicle or its raised structure, the clearance may be reduced to a distance within the designed working dimensions of the insulating barrier.
1910.333(c)(3)(iii)(A)(3)
If the equipment is an aerial lift insulated for the voltage involved, and if the work is performed by a qualified person, the clearance (between the uninsulated portion of the aerial lift and the power line) may be reduced to the distance given in Table S-5.
1910.333(c)(3)(iii)(B)
Employees standing on the ground may not contact the vehicle or mechanical equipment or any of its attachments, unless:
1910.333(c)(3)(iii)(B)(1)
The employee is using protective equipment rated for the voltage; or
..1910.333(c)(3)(iii)(B)(2)
1910.333(c)(3)(iii)(B)(2)
The equipment is located so that no uninsulated part of its structure (that portion of the structure that provides a conductive path to employees on the ground) can come closer to the line than permitted in paragraph (c)(3)(iii) of this section.
1910.333(c)(3)(iii)(C)
If any vehicle or mechanical equipment capable of having parts of its structure elevated near energized overhead lines is intentionally grounded, employees working on the ground near the point of grounding may not stand at the grounding location whenever there is a possibility of overhead line contact. Additional precautions, such as the use of barricades or insulation, shall be taken to protect employees from hazardous ground potentials, depending on earth resistivity and fault currents, which can develop within the first few feet or more outward from the grounding point.
1910.333(c)(4)
“Illumination.”
1910.333(c)(4)(i)
Employees may not enter spaces containing exposed energized parts, unless illumination is provided that enables the employees to perform the work safely.
1910.333(c)(4)(ii)
Where lack of illumination or an obstruction precludes observation of the work to be performed, employees may not perform tasks near exposed energized parts. Employees may not reach blindly into areas which may contain energized parts.
..1910.333(c)(5)
1910.333(c)(5)
“Confined or enclosed work spaces.” When an employee works in a confined or enclosed space (such as a manhole or vault) that contains exposed energized parts, the employer shall provide, and the employee shall use, protective shields, protective barriers, or insulating materials as necessary to avoid inadvertent contact with these parts. Doors, hinged panels, and the like shall be secured to prevent their swinging into an employee and causing the employee to contact exposed energized parts.
1910.333(c)(6)
“Conductive materials and equipment.” Conductive materials and equipment that are in contact with any part of an employee’s body shall be handled in a manner that will prevent them from contacting exposed energized conductors or circuit parts. If an employee must handle long dimensional conductive objects (such as ducts and pipes) in areas with exposed live parts, the employer shall institute work practices (such as the use of insulation, guarding, and material handling techniques) which will minimize the hazard.
1910.333(c)(7)
“Portable ladders.” Portable ladders shall have nonconductive siderails if they are used where the employee or the ladder could contact exposed energized parts.
1910.333(c)(8)
“Conductive apparel.” Conductive articles of jewelry and clothing (such a watch bands, bracelets, rings, key chains, necklaces, metalized aprons, cloth with conductive thread, or metal headgear) may not be worn if they might contact exposed energized parts. However, such articles may be worn if they are rendered nonconductive by covering, wrapping, or other insulating means.
..1910.333(c)(9)
1910.333(c)(9)
“Housekeeping duties.” Where live parts present an electrical contact hazard, employees may not perform housekeeping duties at such close distances to the parts that there is a possibility of contact, unless adequate safeguards (such as insulating equipment or barriers) are provided. Electrically conductive cleaning materials (including conductive solids such as steel wool, metalized cloth, and silicon carbide, as well as conductive liquid solutions) may not be used in proximity to energized parts unless procedures are followed which will prevent electrical contact.
1910.333(c)(10)
“Interlocks.” Only a qualified person following the requirements of paragraph (c) of this section may defeat an electrical safety interlock, and then only temporarily while he or she is working on the equipment. The interlock system shall be returned to its operable condition when this work is completed.
[55 FR 32016, Aug. 6, 1990; 55 FR 42053, Nov. 1, 1990; as amended at 59 FR 4476, Jan. 31, 1994]
Go to www.OSHA.gov for full text of the OSHA regulations.

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Introduction

This control panel is like thousands of control panels out in facilities today, and maybe even many in your facility. It controls a machine on the factory floor. It has four motor starters, individual circuit breakers for those motor circuits, ice cube relays, small fuses, and a control transformer. And on the door there are pushbuttons, indicating lights, rotary switches. In the lower right

corner of the panel is the main circuit breaker. With the door closed, we can still operate the breaker through the hole in the door. Pretty typical of many control panels. The question is how do we de-energize this panel to establish an electrically safe work condition.

Circuit Breakers

Circuit breakers have a line and load side. The line side is where the incoming power is connected. The load side is where the downstream loads are connected. In this case, the downstream loads are everything else in this panel and all of the motors and other components in the control circuit outside the panel. Everything downstream from this main breaker is being protected from over-currents by this breaker.

The question is, does this circuit breaker de-energize this panel? The answer is no. Opening this breaker de-energizes everything in this panel as well as the downstream loads, everything except for the line side of the breaker itself. When this circuit breaker is opened, turned off, the line side of the breaker is still hot. With the line side still energized by the incoming power, the panel has to be considered energized because the main breaker still has a shock and arc flash hazard. You could not use this breaker to establish an electrically safe work condition for this panel.

Electrically Safe Work Condition

To properly de-energize this panel to establish an electrically safe work condition, you would need to locate the circuit breaker or disconnect that feeds power to your control panel. Your lockout tagout procedures should indicate the location of this breaker or disconnect. Once that is found you would open that disconnect or circuit breaker and apply your locks and tag. Return to the control panel and follow through with all of the required lockout tagout procedures. The most important of which is the live-dead-live test to verify zero voltage. Always Test-Before-Touch. And of course, always wear the required PPE while verifying zero volts. Every circuit has to be considered energized until you’ve proven it’s not.

Troubleshooting Example 1

As a troubleshooting example, let us use a situation in which the operator of this machine reports that one of its four conveyors stopped running. You show up and ask the operator what led up to this problem, and they state that that conveyor has been making a lot more noise than usual. A squealing sound. You suspect a mechanical problem, and on an inspection of the conveyor pulleys, it is evident that a bearing has failed thus causing too much load on the motor. Next, we go to the control panel and see that it has an arc flash label that states an arc flash rating of 11 cal/cm2 and a voltage of 480. We must don the appropriate PPE to protect you from such an arc flash and voltage. Because we are only going to do a visual inspection and we are wearing the proper PPE we can proceed. We do an orderly shutdown of everything the panel controls then open the main breaker. We then open the control panel door and see that the motor starter has tripped for that motor. Everything else in the panel appears fine, we reset the motor starter, and close the door. We place our lock and tag on the main breaker, and we perform all other procedures required by our lockout tagout procedures and proceed to repair the bearing.

Troubleshooting Example 2

In the next example, the operator reported the conveyor wouldn’t turn on. There was no mention of a squealing noise. During our initial troubleshooting, we attempt to turn on that conveyor manually and we hear the motor starter turn on, or pull-in as we say,  inside the cabinet. But, the conveyor is still not moving. We don the appropriate PPE, open the control panel door and begin our visual inspection of the panel. We immediately notice the motor starter for conveyor four is showing signs of heat damage. A  dark smoke-like film is on the area covering the motor starter contacts. This, we know from experience, is an indication of poor contact being made by the starter contacts. The other starters don’t show this damage. Now we know we are going to have to remove and replace the starter or at least disassemble it for inspection and repair. In either case, we’ll need to completely de-energize the panel. At this time we’ll need to close the control panel door and open the main breaker. We then must go to the upstream circuit breaker for this panel, turn it off and apply our lock and tag. Upon returning to the control panel, wearing the appropriate PPE we open the control panel door. Using an appropriate volt-meter, we test that meter on a known live circuit, then measure incoming line leads phase-to-phase and phase-to-ground and do verify that we indeed have zero volts. We then retest the meter on a known live circuit to confirm the meter is still working. That is the Live-Dead-Live test. Now we can remove the PPE and begin our repair work. We find the contacts badly damaged from not making proper contact and the carbon buildup inside the starter is preventing the contact assembly from moving freely. We replace the motor starter, and now all conveyors are working fine.

A Shield May Not Work

Some people have suggested that if you add a plastic or metal shield to the main breaker that covers the energized line leads that should solve the problem. It actually can create a whole new problem. OSHA requires electrical equipment to be “accepted, or certified, or listed, or labeled, or otherwise determined to be safe by a nationally recognized testing laboratory.” Underwriters Laboratory is such a lab. If you add a plastic or metal shield to your breaker, it is no-longer UL Listed because it didn’t have your shield when tested. The shield could cause the breaker to operate differently than when it was manufactured and tested, resulting in an unsafe situation.

Control Panel Design

This next piece of advice doesn’t help you with existing control panels but could make your future panels safer and easier to work with where 70E is concerned. That advice is to ask the OEM of your new panels to put this main breaker in a separate box on the side of the panel. Putting the main circuit breaker in a separate enclosure is becoming quite common now, and manufacturers of these boxes are offering this option. Hoffman’s SEQUESTR line of enclosures is one such offering.

Circuit Breaker Panel Boards

I used a control panel as an example here, but all of this applies to circuit breaker panel boards as well, not just control panels. Opening the main breaker of a circuit breaker panel does not establish an electrically safe work condition. If you’re going to add a circuit breaker, for example, turning off the main breaker for the panel board is not sufficient. You will need to open the circuit breaker that feeds this panel to establish an electrically safe work condition.

Conclusion

In conclusion, it is essential that we know what does and what does not make an electrical panel electrically safe. It must be spelled out in your lockout/tagout procedures which disconnect, or circuit breaker removes power from the equipment that will enable us to create the electrically safe work condition. We will wear the appropriate PPE any time the equipment has an energized circuit component above 50V.

Relevant courses

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