Insulated glove and hand tools?
Answered by Bill Rieth, director of industrial safety, Salisbury, Skokie, IL.
Many people incorrectly think of NFPA 70E as a standard only for arc flash hazards; in fact, NFPA 70E is a standard for all electrical safety practices. NFPA 70E addresses all three hazards associated with work on live (energized) parts. These hazards – shock, flash and blast – are defined in NFPA 70E (2004) Annex K. Due to the recent notoriety of the dangers of arc flash, many people forget the dangers associated with shock. Both rubber insulating gloves and insulated hand tools are required by NFPA 70E (2004), and both offer shock protection – but for different types of contact.
Before selecting the proper personal protective equipment for working safely around live parts, the electrical worker first must understand when and where PPE is needed. NFPA 70E (2004) section 130.2 discusses the requirements for approaching and working within shock protection boundaries. Section 130.2(C) lists the requirements for worker insulation while working within the shock protection boundary.
NFPA 70E (2004) also includes section 130.7, which addresses workers' PPE needs, and includes specific requirements for both rubber insulating gloves and insulated and insulating hand tools. These sections are 130.7(C)(6) for rubber insulating gloves and section 130.7(D)(1) for insulated hand tools.
Rubber insulating gloves are designed primarily to protect workers from shock due to direct contact with a live part. These gloves greatly reduce the risk of injury for the worker when used within the proper voltage range. Rubber insulating gloves are rated for a maximum use voltage and assigned a class by ASTM D120. There are six classes of gloves: class 00 = 500V, class 0 = 1000V, class 1 = 7.5kV, class 2 = 17kV, class 3 = 26.5kV, and class 4 = 36kV. A visual inspection and an air inflation test is necessary before each use.
Although insulated and insulating hand tools offer shock protection for the worker, they are considered secondary protection. When working on or near live parts, it is necessary to protect not only the worker but also the equipment being worked on. It is common for a worker to perform a task on de-energized equipment, which is locked out and tagged out, while still being within the shock boundary and in close proximity to other live equipment. In this case a worker could accidentally drop a tool, which then could make contact with live parts. If a noninsulated hand tool was being used in this scenario, it is very possible that a phase-over could result and an arc would occur. Not only would the worker be exposed to injury, but the equipment being worked on would sustain serious damage.
Table 130.7(9)(a) within NFPA 70E addresses the need for both rubber insulating gloves and insulated hand tools, and the necessity of protecting workers from potential shock and flash hazards while performing the required tasks. Rubber insulating gloves and insulated hand tools are vital components of a successful PPE system and must be used in conjunction to provide the maximum protection for workers and the equipment being worked on.