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We're in the process of purchasing a home that is missing GFCI outlets in the garage, and the inspector recommended replacing those.

My first question: if we don't intend on actually using the outlets in the garage, is there any reason to do this? Is there any power surge or whatever that could cause a fire when there's nothing plugged in, or is it only when they're actively being used?

My second question: it seems easy enough, from the DIY videos, to do it ourselves, but we have no electrical experience and, well, I'm really scared of house fires and such. Is it really as easy as it looks to not screw it up? Is it pretty safe?

  • If you want house-fire protection, consider AFCI's. They look for electrical current flow that looks like "arcing" as would occur if a bad wire is trying to burn your house down. Generally GFCIs protect from electrocution hazard (under some circumstances they can help with arcs). If you want the best of both worlds, you can get combo breakers. In fact, in new construction, most circuits must be protected by GFCI, AFCI or both. – Harper Aug 27 '16 at 23:39
  • Don't use AFCIs on circuits where you're likely to run motors like drills, and probably not on your refrigerator circuit, because they trip under certain types of normal loads too. – WBT Aug 28 '16 at 1:33
  • @WBT, AFCI protection is required on most new circuits in a home, regardless of what is plugged in. To suggest omitting them based on what is being plugged in is a bit sketchy. – Speedy Petey Aug 28 '16 at 15:47
  • @SpeedyPetey I don't think it's "sketchy" to recommend choosing protection based on what's plugged in; even code writers evaluate cost/benefit tradeoffs based on expected environmental risk factors & load types. Many power tools produce signals on the line that AFCIs detect as problematic arcing, causing a lot of nuisance tripping. Fridges have also been known to cause nuisance tripping of GFCIs/combos where the cost might be hundreds of dollars of spoiled food and a difficult time accessing the outlet, instead of a few seconds to push reset that nuisance trips in other places often cost. – WBT Aug 28 '16 at 19:53
  • That being said, AFCIs are now recommended for fridges if you're doing work on those circuits, though you may want to think twice about using a dual-function breaker with personnel-protection-GFCI on that circuit, considering e.g. where the outlet is and if it's accessible for other uses. – WBT Aug 28 '16 at 19:56
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GFCIs (in proper operation) interrupt the flow of current when a ground fault is detected.
That is, if the amount of current flowing out of one of the sides of the socket does not exactly equal the amount of current flowing back in the other, it'll cut off power so that no electricity flows out of the outlet. (Some configurations protect "downstream" outlets as well.)

The possible safety benefit comes into play only when something is actually plugged in to a protected outlet, and the real safety benefit is realized when (a) something is plugged in AND (b) whatever that is has a ground fault that would otherwise put someone or some property in serious danger.

The other slight possible benefit of replacing the outlets before use is the possibility of discovering some existing dangerous wiring issue if it exists in the current outlets, but the odds of that are relatively low and the odds of you putting such an error in (especially if you do it yourselves!) seem a whole lot higher. If you're concerned about the existing wiring to outlets you aren't using, you can probably just turn off the circuit breaker to that circuit, so there won't be electricity in the outlets. This assumes you're not using anything else on the same circuit.

If you're not using those outlets, there's no benefit to replacing them right away, and there is of course a cost to doing so. You could buy replacements and wait on installation until some time when you have an electrician over to the house for something else, when the marginal cost of replacement is minimal. Then you can benefit from GFCI protection if/when you do start using those outlets, and (assuming they still work) have one less item on the next buyer's inspection report to help that buyer feel more at ease.

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    Thank you for your thorough answer! Really appreciate it. – ShannonC Aug 27 '16 at 16:38
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The GFCI (aka GFI) protects against unbalanced electric flow. This is one of the greatest leaps in personal safety technology to be widely available and deployed. It is now very inexpensive (<$16) to protect a whole circuit.

No, the house is not in any danger from having non-GFCI circuits. It is 99.9% a personal safety issue. If a device you are using somehow fails and delivers some current through your body—instead of through the electrical circuit—the GFCI detects this circuit imbalance and, within 1/20 of a second, "trips" and stops the shock.

Sure you can forego upgrading your outlets. Your garage probably has only one or two circuits, so you can save $30. Or if you would have to hire an electrician, you can save $120 or so.

To me, having GFCIs is a great value. Unless you and all your guests don't use electrical devices, it is excellent peace of mind knowing they won't be shocked. Of course they can still accidentally drill their limbs, burn and drop heavy stuff on themselves so a garage may not be a first to incarcerate teenagers....

As far as DIY work, replacing an outlet is 1 or 2 of out a possible 10 in complexity:

  • Turn off the circuit
  • Verify the outlet is dead: plug in a known working portable device (radio, light, hair dryer, etc.)
  • Remove the cover plate screw(s)
  • Loosen the two screws holding the outlet in.
  • Pull outlet out, stretching the wires to a convenient working position.
  • Notice the wire color pattern. In North America, it should be black wire to bronze connector, white wire to silver connector, and bare (uninsulated) or green wire to the outlet frame. If not wired this way, check other outlets with an $8 outlet tester.

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  • Remove wires from old outlet. There are two predominant fastening means: screws on the sides or "quick install" holes. For the quick install holes, there should be (another) small hole where inserting a narrow screwdriver or carpentry nail makes it release the wire. Failing that, you might be able to muscle the wire out with a forceful quick tug. Or just cut the wire.
  • Prepare the wires and connect to the new outlet. If using the screws, make the wire go in the direction the screw turns when tightening. Otherwise tightening will push the wire out from under the screw head.
  • Test wire connections mechanically by tugging firmly to make sure they won't slip out.
  • Fold and push wires into box so they stay out of the way. Be sure the bare wire is fully in the back and nowhere near the sides of the outlet, except where it is screwed to the outlet frame.
  • Push outlet into box and tighten screws.
  • Install outlet cover.
  • Turn on circuit.
  • Insert tester into outlet to verify correct wiring.

It may seem like a lot of steps, but it is quite simple.

By the way, that button on the outlet tester puts a small load (0.01–0.03 amps) between the hot wire and ground. That will trip a correctly working GFCI. If the circuit has no GFCI, pressing the button won't do anything.

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    You only need a GFCI outlet on the first outlet in the string. The downstream outlets "tend to" inherit the GFCI protection from the first outlet. By "tend to" I mean that is the easiest way to wire it. A determined peson could wire it so the downstream outlets aren't protected, but it would require additional splices and wires. – Harper Aug 27 '16 at 23:34
  • @Harper It may be the easiest way to wire it, but if you have loads connected, the tiny amount of normal leakage from each can add up and increase nuisance tripping. – WBT Aug 28 '16 at 1:35
  • There are some potentially important details left out of this answer. For example, in "prepare the wires and connect to the new outlet," it matters which way the hook goes around the screw, so that the torque from screwing it down strengthens the connection rather than weakens it. And you recommend leaving the ground disconnected? Why? I don't think I'd recommend this OP making this a DIY project, especially by this guide. – WBT Aug 28 '16 at 1:53
  • @WBT: I did gloss over which way the screw goes, but indirectly cover that by "testing the mechanical connection". I was trying to be concise, but maybe a little more detail would be helpful (which I just added). Where do I recommend leaving the ground disconnected? – wallyk Aug 28 '16 at 1:57
  • @wallyk "Be sure the bare wire is fully in the back and nowhere near the sides of the outlet." I think these are generally signs that a nervous OP with zero electrical experience should not be following a guide like this one from someone who (to her) is a random stranger on the Internet. For another example, in "testing the mechanical connection" especially with quick-install holes, she might pull the wire partially out leaving a weak and arcy or glowing connection that later causes major issues, and not know it until it's too late. – WBT Aug 28 '16 at 2:02

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