Ground Fault Circuit Interrupters (GFCIs), Part 2

Last week I gave an overview of what GFCI outlets are for - the long and short is that GFCIs are life safety devices; they prevent lethal shocks.  This week I'll talk about the different types of GFCI devices, how to test them, what drives me crazy with them on home inspections, and what some of the newer features are.


The two most common types of GFCI devices are circuit breakers and outlets.  A GFCI circuit breaker gets installed at the electric panel, and protects the entire circuit.  This is a handy way to make sure everything on the circuit gets protected, and there is no need for individual GFCI outlets anywhere in the circuit.  The other type, which everyone has already seen, is an outlet.  The most common type of outlet is a duplex receptacle, which is shown below left.
 
One GFCI outlet can protect several other non-GFCI outlets when wired properly.  Every GFCI outlet has screws behind the outlet labeled "line" and "load".  The current coming in to the outlet must always be connected to the "line" side of the outlet.  If more outlets are going to be protected by the GFCI, they can be wired to the "load" side of the outlet.   Many houses built in the eighties will have the exterior outlets, garage outlets, and basement bathroom outlets wired downstream from a GFCI outlet in the upper level bathroom.  Today it's common for a GFCI outlet at the kitchen countertop to protect several other outlets.  This saves money.



A redundant way to wire  GFCI outlets is to wire one GFCI downstream from a second GFCI outlet.  This is wasteful, pointless, annoying, and it makes things difficult for the home inspector and anyone else that might trip the outlet, especially if the first GFCI outlet is hidden! Please don't do this.

GFCI outlets should be tested every month because they can go bad, and a defective GFCI outlet doesn't provide any life safety protection.  To test a GFCI outlet or circuit breaker, simply press the test button.  Here are the possible outcomes you can have by testing a GFCI outlet with the test button:

• Acceptable - The reset button pops and the power goes off.  The GFCI device is functioning properly.  Simply press the reset button to restore power.
• Unacceptable - The reset button doesn't pop.  This means the outlet is defective and should be replaced.
•  Unacceptable - The reset button pops but the power doesn't go off.  This means the line and load are reversed at the outlet. This should be corrected.  Newer "SmartLock" GFCI outlets that have a little lock symbol on the front have a built-in safety feature that prevents the outlet from getting energized if it's incorrectly wired.
• Unacceptable - The reset button is already popped, the power is off, and the reset button won't go in.  This can happen on the newer "Smartlock" GFCI outlets if they're improperly wired or the outlet has gone bad.
• Acceptable, but annoying - The outlet loses power when tested, but the reset button doesn't move.  This means someone wired the GFCI outlet downstream from a second GFCI outlet.  Shame on them.

Another way to test GFCI outlets is to buy a tester.  This is a great way to test standard outlets that are wired downstream from a GFCI device.  Just plug it in to an outlet and press the test button.  If the power goes out, the GFCI device is working properly.  If the power stays on, it doesn't mean the GFCI device is defective - sometimes GFCI testers won't trip GFCI outlets.  If this is the case, try the test button at the outlet.

Why do GFCI outlets go bad? I honestly don't know, and if anyone reading this blog can tell me, I'd be interested in hearing about it.  From my own experience, I've found that after a GFCI outlet has had a lot of power running through it, it will often fail.  For example, any time I'm working on a remodeling project and I'm running a bunch of power tools through a GFCI, it goes bad within about a month.  I've heard of home builders wanting to put all of their GFCI outlets on the inside of the house because there's this idea that cold Minnesota weather makes GFCI outlets go bad, but I haven't experienced that myself, and a study on GFCI outlets has shown that temperature doesn't have any effect.

RELATED POST:  GFCI Outlets, Part One


Reuben Saltzman, Structure Tech Home Inspections – Email – Home Inspector Minneapolis

Ground Fault Circuit Interrupters (GFCIs), Part 1

For this this week and next week's blogs, I'll be waxing on GFCI outlets.  I'll talk about what they do, why they're so important, what you need to know about them, and how to test the outlets in your own home.


First, a quick refresher. In my blog about reversed polarity outlets, I explained that there are two wires that conduct current - one get connected to the earth (grounded) and the other doesn't.  The grounded conductor should always be white, and is referred to as the "neutral" wire.  The ungroundedconductor is usually referred to as the "hot" wire, and it can be any color besides white or green, but it's typically black.  Because the neutral wire is connected to the earth, any time you're in contact with the earth and you touch an ungrounded wire, you'll complete the circuit and you'll get a shock.  The general, technical name for this event is a ''ground fault", because current is getting back to the ground in a way that it shouldn't (it's using you!).

Not all shocks are the same. Here's where we'll get in to a little more detail about what happens when a human comes in contact with an ungrounded(hot) conductor.

• No shock. If I could magically levitate and grab on to a ungroundedconductor, I wouldn't get a shock.  I'm not providing a path back to the earth, so the electricity doesn't have anywhere to go.  This is why birds can sit on power lines without getting a shock.  No ground fault.

• Small shock. If I were working on the second story of my wood-framed house, wearing rubber soled shoes, standing on the carpet, and then came in contact with an ungrounded conductor, I would probably receive a relatively mild shock.  The current has a difficult time traveling through my skin, through my body, through my shoes, through the carpeting, through the wood framing in the house, and eventually back to the earth.  I say 'relatively' mild because this has happened to me several times, and I'm still here to tell about it.  It still hurt like hell every time, and it's always dangerous. This is a ground fault.

• Severe / lethal shock. If I were holding on to the kitchen faucet with a wet hand and I touched an ungrounded conductor with my other hand, which was also wet, I'd probably get killed.  Having a wet hand will make it easier for electricity to pass through my skin.  After the electricity passes through my body, it has a very easy time getting back to the earth; it will pass through the kitchen faucet to the water pipes, which are directly connected to my electric panel.  This ground fault could easily be enough to kill me.

To prevent lethal shocks through ground faults, special electrical devices called Ground Fault Circuit Interrupters, or GFCIs, are required in homes.  If a GFCI device detects a ground fault, it will shut off (or 'interrupt) current within a fraction of a second.  It won't be fast enough to prevent a painful shock, but it's enough to keep you from getting killed.

GFCI devices were first required near swimming pools in 1971.  Today they're required in areas where lethal shocks are most likely to happen - typically at areas that are wet and have good contact with the earth.  These areas include the exterior, garages, kitchen counter tops, bathrooms, unfinished basements, crawl spaces, and outlets within 6' of laundry sinks, utility sinks, and wet bar sinks, among other places.  For an excellent one-page chart that lists all the locations and shows when the specific requirements went in to effect, click here.

That's enough information on GFCIs for this week.  Next week I'll talk about the different types of GFCI devices available, the difference between new and old GFCI outlets, how to test them, how they irritate me, and how to save money while installing them.

Reuben Saltzman, Structure Tech Home Inspections – Email – Home Inspector in Minneapolis