How GFCI Receptacles Keep You Safe

Two-thirds of all electrocutions in U.S. homes could be prevented if people installed the receptacles.

By Max Alexander of This Old House magazine


A ground fault happens whenever electricity escapes the confines of the wiring in an appliance, light fixture, or power tool and takes a shortcut to the ground. When that short cut is through a human, the results can be deadly. About 200 people in the U.S. alone die of ground faults each year, accounting for two-thirds of all electrocutions occurring in homes.

To prevent such accidents, Charles Dalziel, a professor of electrical engineering at the University of California, invented the ground-fault circuit interrupter (GFCI), in 1961. Most of the time, his invention does nothing; it just monitors the difference in the current flowing into and out of a tool or appliance. But when that difference exceeds 5 milliamps, an indication that a ground fault may be occurring, the GFCI shuts off the flow in an instant — as little as .025 second.

GFCIs are required by the National Electric Code in all new kitchens, bathrooms, crawl spaces, unfinished basements, and most outdoor receptacles. Owners of older houses can retrofit $10 GFCI receptacles at those locations or have GFCI breaker switches (which run as much as $108 for 50-amp models) mounted in the main breaker panel. Portable GFCI adapters, which plug into regular wall receptacles, are available for about $40.

“The great thing about GFCIs is that they protect you whether or not your wiring is grounded,” says Bill Grande, manager for safety products at Leviton, a manufacturer of GFCIs. Because lightning and other power surges can damage a GFCIs delicate circuitry at any time, Grande recommends the following monthly test: Plug in a light fixture and turn it on. Then push the device’s test button. If the light stays on, the GFCI needs to be replaced.

One of the most common comments I make when inspecting a home is one that points out moisture damage at the exterior door jamb. There are typically a couple potential causes for the damage. It is a common issue that can sometimes be repaired without replacing the door. Using materials that resist rot can help minimize further damage as well as installing a storm door.  Depending on your skill set and the amount of damage, this might be a project you could do yourself. Sometimes the damage can extend to the sub-floor or rim joist. These conditions are more difficult to address on your own.

These conditions are more common than you’d want to believe. The pooling water on the ground under the house, elevated moisture content in the wood joists, and the sagging insulation are some signs of a sick crawlspace. The conditions allow for some significant structural damage over time and must be corrected in order to mitigate some potentially costly damage.

The level of damage often depends on the extent of the problem and the length of time in which it has existed. Here are some of the more frequently identified causes:

  • Ground water
  • Evaporation
  • Plumbing leaks
  • Poor venting practices

Downspouts that dump against the foundation are a major contributor to the first issue. The water will choose the path of least resistance and end up under the house.

Missing or damaged vapor barriers can also be a contributor. Depending on the moisture content in the soil, a missing barrier introduces a lot of water thru evaporation.

Plumbing leaks in a crawl offer go undetected. Depending on the severity, a lot of water can sit in the crawlspace and this can go on for a while.

Poor venting can cause issues that are more difficult to identify. Many times I’ll exit a crawlspace durning the summer months and my back will be wet. This is caused by the hot humid air being pulled into the cool crawlspace where it condenses on the floor joists and insulation. This, over time, can cause many issues like rotting wood. Here is a great article that explains better what is taking place and the problems that can occur.