One of the most important safety devices used in modern wiring is the GFCI, also known as an RCD (residual current device), but perhaps most commonly known as a GFI (ground fault interrupter). Typically, these are built into electrical outlets, and are most commonly located in bed-rooms, kitchens, laundry rooms, and bathrooms where most electrical shocks occur. It’s also a good idea to locate these in outdoor porch and patio outlets, and in workshops and garages. The safest possible use of GFCIs involves installing one for every circuit in a building. Then, a GFCI will provide protection for ground shorts occurring anywhere in that building. GFCIs are also built into the cords of hairdryers, and other electrical appliances and tools which are used near water. Before GFCI installation became law for new homes and new hairdryers, scores of deaths occurred in the U.S. after hairdryers were dropped into sinks or tubs full of water, and people reached in to retrieve them. These deaths still occur, because many older homes have not been updated with GFCIs, and many older model hairdryers are still in use. However, newer hair-dryers have been saving lives, and GFCIs located in outlets are saving lives when accidents occur with older hairdryers.
Although most of us are familiar with GFCIs and their identifying buttons, it’s a good idea to understand how these work. Let’s use the hairdryer accident as an example. First of all, without a GFCI, when an older style hairdryer is dropped into a sink full of water, the electrical current becomes shorted to ground from the live wires inside the dryer. When this happens, high voltage electricity is flowing out of the hair dryer and through the water to ground, typically through a metal drain. Next, imagine that someone with wet feet standing on a wet floor, or in a bathtub full of water reaches down and grabs the hairdryer. The electricity now begins flowing through that person’s body to the floor, which acts as a ground. Technically, the electricity flows from ground to the hot electrical contacts in the hairdryer, but it’s helpful to think of the hairdryer as the source. An electrical shock from household current can cause death when a victim’s heart is stopped by this shock. Although it may seem foolish to grab a wet hairdryer from a sink, this usually happens as a quick reflexive action, before anyone can imagine the consequences.
Now, let’s see what happens with the same hairdryer accident when a GFCI exists in the hair-dryer’s cord, or in the electrical outlet. As soon as water enters the hairdryer and the electricity is shorted to ground, the GFCI detects the short, and turns off (interrupts) the electrical current. This happens extremely fast, usually in about 25 thousandths of a second (25 ms). So, long be-fore anyone’s hand can touch the water, the flow of electricity has been stopped.
Of course, a wet hairdryer is only one of many possible ways in which dangerous electrical shorts can occur. Frayed or cut electrical cords, old and cracked insulation, worn out switches and outlets, and a host of other conditions can cause shorts resulting in electrical fires and accidental electrocutions. In fact, over 40,000 electrical fires occur in the United States every year. In addition, many unnecessary deaths occur from these fires and electrical shocks. This is why installing GFIs in every circuit is so important. If you are unsure if the wiring in your home or business has sufficient GFI protection, call a qualified electrician and schedule a safety inspection as soon as possible. If you live in Austin or central Texas and would like to schedule an inspection by one of our licensed electricians, please call Bryant Electric Service at 512-402-858.