Because electricity is used in every workplace, the threat of electrocution is present in almost every job. Simple steps can protect workers and prevent electrical accidents.
When your employees think of electrical hazards, they may get an image of high voltage overhead power lines. Unless they see such a threat, they may not realize they’re in danger when they get too close to some other electrical hazard.
Take the case of the worker who was drilling holes in 2 x 4 supports for a bracket that needed to be bolted into place. The drill bit needed sharpening, but to save time the worker just pushed harder. He felt the drill getting hot, but he still didn’t stop. He grabbed a water pipe for support as he pushed even harder on the drill. At that point electrical current surged from the drill through the worker’s hand, across his heart and through the other hand. Fortunately for this employee, his co-worker knew CPR and was able to resuscitate him until help arrived.
Most employees in such a situation wouldn’t be so lucky. Fatalities are common when leaking current finds a path through a grounded worker.
The basic problem in this case and others like it is that employees are not trained to recognize electrical hazards. Here the employee had plenty of warning that something was wrong when the drill became hot. Grabbing hold of a metal pipe showed that the worker didn’t have a clue to the danger he was in.
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Principles of Grounding
If your employees have a good understanding of how electricity works, they will be in a better position to avoid hazardous situations. Explain to them that electricity must have an uninterrupted path or circuit to follow. If their body becomes part of that circuit, the electricity will pass through it.
How can this happen? There may be a hidden hazard inside a power tool, known as a ground fault or a “short.” This is a small amount of current that “leaks” into the exposed, metal parts of the tool. It can occur because of damage that causes internal wiring to touch those exposed metal parts. When that happens, the entire device can become as electrically alive as the power line to which it is attached.
To direct the flow away from the person holding the tool, there must be a path of least resistance, known as a ground. For instance, if your workers have dry hands and feet, the electricity will follow the ground wire, because it has less resistance than they have. If their hands are wet or they are standing in water, their resistance will drop rapidly and the electricity will run right through them. Touching a metal pipe, as the employee did in the incident described previously, will also ground the person. Injuries can range from minor burns to death.
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The amount of current it takes to injure or kill a normal adult is so small that it could happen before a fuse blows or a circuit trips. That’s why OSHA recommends that employers use ground fault circuit interrupters (GFCIs).
There are three types of GFCIs:
- Receptacle type—installed inside the outlet
- Circuit breaker type—installed inside the circuit breaker box
- Portable type—plugged into an existing outlet (the tool is then plugged into the GFCI)
This device constantly monitors the electric current going into the tool compared to the amount coming out. When the amounts are equal, everything is working fine. However, if there is less current coming back than went in, the GFCI cuts off the flow of electricity within as little as 1/40 of a second, quickly enough to prevent electrocution.
Tomorrow, we’ll talk more about electrical safety, focusing on the critical issue of employee training.