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We are updating the receptacles in our kids' room. The current ones accept two prong plugs so I doubt that there is a ground wire.

Since we're upgrading, for the kids' safety, does it make sense to put GFCI's in the room?

  • It would probably be simpler (and cheaper) to install GFCI breakers as needed for bedroom circuits. If I recall correctly, it's legal to use 3-prong outlets even when grounding conductors aren't available because folks tend to use those "adapters" incoorectly anyway, increasing risk. 3-prong outlets are much cheaper, too. Related: diy.stackexchange.com/questions/36426/… – isherwood Jan 5 '17 at 21:28
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What age are the kids?

Most kids have been surviving without GFCI protection for many decades now. But a GFCI has very few disadvantages other than adding a bit of cost.

On the other hand, once you go that far, the question does arise of whether their own room is the only place a problem might arise and whether you might as well invest in protecting the whole house.

In the end, this is a cost/benefit judgement call that only you can make.

  • If it's cost would you recommend GFCI/AFCI breakers? :) – milesmeow Jan 5 '17 at 21:57
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    GFCI breakers run about $40 a piece. GFCI outlets are about $15-$20. In either case, you only need one to protect the circuit. Current code requires AFCI breakers for bedrooms in the US, so you might want to go that route - pricey though. – CoAstroGeek Jan 5 '17 at 22:02
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    AFCI and GFCI protect different things. I think there are AFCI/GFCI combos right? Probably $$$ – milesmeow Jan 5 '17 at 22:39
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    I dislike GFCI breakers since, if it trips, you have to go to the breaker box to reset it, instead of to the outlet (or an outlet in another room). – DoxyLover Jan 5 '17 at 23:12
  • @milesmeow -- DFCI breakers and receptacles are now available, yes. – ThreePhaseEel Jan 5 '17 at 23:19
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Wait. "Updating the receptacles"?

You're saying they.re "currently 2-prong" like you see them being something else soon?

Change to outlets with anti-tamper shutters, definitely.

Change from black to beige, sure.

Change from 2-prong to 3-prong just la la la? No! You can't do that!.

Because if a piece of equipment expects ground to be there and it isn't -- instead of a ground fault shunting harmlessly to ground, it will "pull up" i.e. energize the frame of the equipment. And if anyone touches that and also something near neutral or ground, they get dead.

Protection features

If you put a GFCI on a non-grounded outlet, the exact same thing will happen, except the GFCI will trip in a few milliseconds when it detects not all the current going out the hot pin is coming back the neutral, and so the electrocution will end before it can do real damage. In theory. If the GFCI works.

If you had a grounded outlet, the ground fault would have faulted directly to ground, and resulted in an overcurrent trip at about 30-40 amps, or a GFCI trip at 8 milliamps if GFCI equipped... and in any case no human would be shocked.

So having discussed two protection devices, let's talk about the third and fourth. Anti-tamper shutters cover the holes to prevent inquisitive children from poking things in there.

If they manage to anyway, arc-fault circuit interrupters (AFCI) hear the characteristic sputter of an arc, this also protects frayed cords and building wiring that might be faulty.

In the law, if you leave a part alone, it's grandfathered. If you mess with it, that part becomes new work and you must bring it full up to code for new work. Which requires grounding, AFCI breaker, and anti-tamper doors. GFCI is not required in bedrooms, but is useful.

Options, least to best.

Leave it alone. Grandfathered. Unsafe. Inelegant.

Replace with 2-prong of your choice of style. The circuit is grandfathered, the new receptacle needs anti-tamper doors.

GFCI receptacle. This is the only legal way to provision 3-prong outlets without a ground behind it. The outlet needs to be marked "no equipment ground" and it'll do nothing to protect electronics from ESD and lightning.

Check for ground already present in the box and get lucky, in which case you can just add a 3-prong (with shutters). Unlikely, or the builder would've put a 3-prong there.

Retrofit ground to the box. The latest Code greatly blesses doing this by making many methods legal which were not before. You can argue with the inspector whether this is "new work" enough to require an AFCI.

Pull a whole new cable run. Only do this if the old cable looks damaged. However this "new work" requires an AFCI breaker.

Optional:

GFCI. I described how it protects from ground-fault shock between normal pathways and a third ground. It does not protect from normal-pathway shock, like chewing through a cord or poking a paper clip in each hole. AFCI's help there. GFCI protection can be done as a breaker or receptacle, but you're better off doing a receptacle because a) they are cheaper and b) the breaker option is better reserved for AFCI.

AFCI. This is a microcomputer which listens to the power line, for telltale "arcing" waveforms/sounds. This protects your kid if he sticks a chain of paperclips in the holes, because something in there is likely to sputter and catch the attention of the AFCI. AFCI's come best as circuit breakers; the receptacle version does not protect as well, and it conflicts with also having a GFCI receptacle.

You can get combo AFCI/GFCI breakers. You can also get combo receptacles (thank you ThreePhaseEel), but here's the thing: An AFCI receptacle does nothing to protect the wire between it and the breaker panel, which defeats some of the purpose! So if the AFCI is mandatory, I believe it can only be put in a receptacle if there's all-metal conduit or armored cable between panel and AFCI receptacle.

  • Well, MC works too for the run between panel and AFCI receptacle...(might be a fair bit easier to deal with than conduit, especially with the advent of MCI-A cables) – ThreePhaseEel Jan 6 '17 at 23:12
  • @ThreePhaseEel Really? I thought MC shield couldn't be used as a grounding path. – Harper Jan 8 '17 at 21:21
  • for straight MCI (interlocked armor) cable, that is true. However, you don't need the metal sheath to be a grounding path in order for it to keep an arc fault from igniting stuff. Also, for MCI-A (interlocked armor with integral armor grounding) or the rarer MCC/MCS (smooth/corrugated armor) cable, it is OK to use the armor as a grounding path. – ThreePhaseEel Jan 8 '17 at 21:55

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