All About GFIs and T&P Safety

GFI OutletBy Bob Petersen, Precision Inspection
This month I am going to discuss two of the more critical mechanical components of a house, the ground-fault interrupter (GFI) and the temperature and pressure relief valve (T&P).

GFI’s (also called gfci for “ground fault circuit interrupter“) are generally found only on homes of relatively recent construction (since about 1980). However, one can be installed in any home and is recommended.

GFI’s were included in the National Electric Code in 1973 but may not have been adopted by various city building codes until later. They were developed due to the large number of injuries and fatalities caused by relatively minor shocks from hand held appliances and power tools.

GFI’s come in two types. The first is similar to a normal electrical outlet except the device contains the GFI mechanism and test / reset buttons.

The second is similar in appearance to a normal circuit breaker with the addition of a test button and is found in the breaker box.

Both types can sense current leakage as small as 5 milliamps. In comparison, a regular circuit breaker will only trip at its rated amperage (a minimum of 15 amps.) A shock from a 15 amp circuit is very strong and can be lethal.

The National Electric Code requires GFI circuits at all accessible garage, bath, outside, & kitchen countertop plugs as these are areas where people may come in contact with water or an improperly grounded tool. Any outlets UNDER a home or at a spa tub or sink must be this safety type outlet as well.

It is strongly recommended that you test the GFI plugs or breakers in your house often by pressing the test button. An even better way to test the GFI is to purchase a GFI tester which can be found at Home Depot or Lowes. Use the tester on the plugs to determine if the GFI is tripping at the proper level. In my experience, fully 1/3 of the GFI circuits we test weekly are improperly wired or defective, which constitutes a hidden shock hazard to all occupants of the house. Have you checked yours recently? GFI outlets are relatively inexpensive ($12) and are easily installed.

The temperature & pressure (T&P) relief valves are found on all water heaters and are as critical to personal safety as the GFI devices.

The T&P valve is a safety valve which allows for the release of excessive pressure that may build up inside your water heater. The most common cause for such excessive pressure is the burner or elements staying on continuously. If the T&P valve is installed incorrectly or not functioning properly, the water heater becomes a bomb and a very powerful one at that.

The average 30 gallon [small] water heater will explode with a force equivalent to 2 pounds of dynamite ! I have seen videos of exploding water heaters and it’s quite scary how much damage occurs…

The T&P valve must be sized correctly for the water heater and be installed on the tank and not on the water lines connected to the it. Proper installation is critical because the valve has a short probe on it which is designed to constantly sense the temperature & pressure in the tank. The valve will not function properly if placed anywhere else.

The valves wear out & can get stopped up with mineral deposits. They should be tested monthly. A test lever is conveniently mounted on top of the valve for this purpose. Tested YOURS lately? We find a VERY large number of valves installed incorrectly. If the people living in these houses knew the potential consequences of this, they might not sleep as comfortably at night…

Courtesy of Bob Petersen
Precision Inspection

Posted by Steve
8 years ago

Steve is a Real Estate Blogger, Husband and Dad, UT Austin Grad, Runner, Real Estate Broker and owner of Crossland Team and Crossland Real Estate in Austin TX.

Click Here to Leave a Comment Below

Leave a Reply: