70E Topics Snapshot Introduction
This is meant to serve as a snapshot of important 70E topics.
Before work begins on equipment that would expose workers to electrical hazards, it must be de-energized, unless you can justify working live. OSHA and 70E are clear on this. The three ways to justify working live are if de-energizing causes increased hazards, as in life support or alarm systems; if it is infeasible due to equipment or operational limitations; or if the voltage is below 50v. OSHA doesn’t think many things are infeasible and money, downtime or additional costs can never be part of the decision process.
Electrically Safe Work Condition
An electrically safe work condition must be established by following your employer’s lockout/tagout procedures. These procedures must include a “live-dead-live” test with your multimeter. Always test before touch. All circuits must be considered live until a live-dead-live test verifies an absence of voltage. You will need to wear the proper PPE during the “live-dead-live” test.
First, test your meter on a known live circuit, then verify an for the absence of voltage on the equipment you are de-energizing by measuring phase-to-phase and each phase to ground. Then retest your meter on a known live circuit. A non-contact voltage detector is not suitable for verifying zero volts. You must wear PPE while performing the “Live-Dead-Live Test.”
Qualified For The Task
Only qualified workers are allowed to work on equipment that has not been de-energized. You can be considered qualified for some tasks or equipment but not others. Whatever work you are doing on energized equipment you must have been trained for, including receiving safety training for that task and equipment. The employer must document when training occurred, and its contents.
A qualified worker must demonstrate to management, at least annually, that they are following the employer’s electrical safety program. Non-compliance will trigger retraining for that individual. This demonstration can be accomplished by annual audits or through periodic supervision.
Energized Electrical Work Permit
While working inside the restricted approach boundary, an EEWP is required. Among other things, it must describe the work to be done, hazards faced, steps taken to protect the worker, the justification for working live within the restricted boundary and it must be signed by those approving of the live work. Diagnostics and visual inspections are exempt from an EEWP.
Assess Risk Before Work Begins
A shock and arc risk assessment must be completed, and documented, before working on energized equipment. A qualified person must perform a risk assessment that identifies the hazards, estimate the likelihood and severity of possible occurrence and determine if additional precautions are necessary. The hierarchy of risk control must be followed – with PPE as a last resort.
Shock Risk Assessment
The likelihood of an occurrence increases as you cross the Limited and Restricted Approach Boundaries. The voltage determines the severity. Work inside the limited approach boundary triggers establishing an Electrically Safe Work Condition. While work inside the restricted boundary requires the worker to be insulated from the live parts and may trigger an energized electrical work permit.
Arc flash Risk Assessment
The arc flash risk assessment must estimate the likelihood and severity of an occurrence. Table 130.5(C) Estimate of the Likelihood of Occurrence of an Arc Flash Incident for AC and DC Systems identifies the likelihood. This table is used for either method of PPE selection and does not address severity. Severity will be addressed by the method you choose for arc flash PPE selection. Either the PPE Category Method or the Incident Energy Analysis Method
Hierarchy of Risk Control
The HRC will guide you when implementing preventive and protective measures. Elimination, substitution, engineering controls, awareness, administrative controls and as a last resort PPE.
Arc Flash PPE Category Method
This method utilizes tables that list equipment and tasks, then estimates what the PPE category of clothing would be needed. This method requires you to know the fault current and clearing time of your circuit. You can not use the PPE category method and the Incident Energy Analysis Method on the same piece of equipment.
Incident Energy Analysis Method
This method involves an extensive power study conducted by electrical engineers. Real world information collected in the field from your electrical distribution system will be used to calculate the incident energy for a piece of equipment. The clothing worn while being exposed to live conductors at that piece of equipment has to have an arc rating at least as high as the calculated incident energy. The incident energy that is found by the study is not permitted to be used to specify an arc flash PPE category.
Equipment requiring servicing and maintenance while energized are required to be labeled. This label must contain voltage, arc flash boundary, and information to determine the arc rating of PPE. Equipment such as junction boxes, motor connection boxes, raceways and the like will not require a label because they aren’t typically opened for service while energized and they don’t necessarily have exposed conductors.
Electrical Safety Training
Qualified workers need electrical safety training at least every three years, sometimes sooner. This training includes any changes in the standards or the company’s procedures. The training dates, attendees, and the training contents need to be documented.