Dr-Fix-It! Notebook Archive:
Keeping Current . . .
The next time you buy a GFCI, make sure it complies with the new UL requirements. Be sure it was manufactured after January 1, 2003.
In a short circuit, a large electrical current flows through the wiring. That's when a circuit breaker trips to prevent overheating the wires. But the current level needed to trip a circuit breaker is much higher than the amount needed for a dangerous electrical shock. Far less than 1 amp of electrical current can be fatal while most circuit breakers trip at current levels in excess of 15 or 20 amps. In a ground fault condition, a person might be at risk from serious electrical shock even though the circuit breaker senses normal current..
What's a ground fault? Sometimes, through normal use, a tool or appliance can become worn down in such a way that it works fine but electricity can "leak" out of it. Something as minor as a scratch in the coating of an internal part or a small crack in the insulation of a wire are examples of this kind of wear and tear. But the most common cause of "electrical leakage" is the presence of water inside the tool or appliance. If a person touches a wet tool or appliance, his body can become the way electricity travels to ground. This is a ground fault, and it can kill.
Ground Fault Circuit Interrupters (GFCI or GFI) are easy-to-install and inexpensive. They are designed to replace ordinary receptacles in wet or damp locations. 1975, the NEC (National Electrical Code) mandated that GFCIs would be installed in all places where water and electricity are likely to mix.
What does a GFCI do? When an appliance is plugged into a GFCI receptacle, the GFCI monitors current flowing through both the hot and neutral conductors. If everything is working well, the amount of current flowing out through the hot conductor should exactly equal the amount flowing back through the neutral conductor. If the current levels are not exactly equal, then the current is "leaking" out somewhere. The GFCI will detect and measure this imbalance, and when it reaches a level of only 5 milliamps (.005 amps), the GFCI shut off power at the receptacle.
While GFCIs have had a significant impact on consumer safety since their introduction over 30 years ago, there is a possibility that they can be become damaged and no longer offer protection from ground faults". According to the Leviton Institute, voltage surges from lightning and other sources can damage GFCIs just as they would any other electronic device. That's why it's crucial to test these devices once a month to make sure they're working properly.
It is simple to test a GFCI: Just plug a tool or appliance into the GFCI outlet. Turn on the tool or appliance. Push the TEST button on the GFCI. If it is working properly, the GFCI will trip and power to the tool or appliance will be cut off. If power did not go off when you pushed the TEST button, there is a problem. Testing is that easy!
In the past, it was not uncommon to find a GFCI wired incorrectly. The line and load wires must never be confused and always be attached to the proper posts. The neutral and hot sides of the GFCI must also be observed. As of January 1, 2003, Underwriters Laboratories Inc. (UL), mandated all GFCIs manufactured as of that date need to comply with new standards to include increased surge immunity, overload protection, corrosion resistance and electrical noise resistance. In addition, all GFCIs manufactured after January 1, 2003 must provide a some sort of indication for incorrect wiring, helping to prevent installation errors.
Replacing your current GFCIs with models that meet the new, tougher requirements will help ensure that they withstand conditions that have damaged GFCIs in the past. And, remember to test your GFCIs every month.
Thanks to The Leviton Manufacturing Company - the pioneer in GFCI technology.