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I have an old house, the electrical cabling only has two wires with no ground wire. When I bought it years ago, I had an electrician in to look at it, and they put GFCI blank-face receptacles on every circuit just outside of the electrical panel. So every outlet and fixture in my house is on the load side of a GFCI.

However, they didn't replace the existing breakers with AFCIs. My question is whether the GFCIs provide adequate protection against arc faults, or if I should also still have AFCI breakers.

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    Does the electrical cabling have a metal jacket or run in metal conduit? – Harper - Reinstate Monica Feb 10 at 17:19
  • "Years ago" is a little vague, it is quite possible that the GFCI upgrade was done prior to adoption of AFCI code requirements, so if you are not making modifications (or only making minor changes) there may be no legal requirement for AFCI's to be installed. – NoSparksPlease Feb 10 at 18:24
  • No, the old cable isn't in metal jackets. The cables themselves are black and they have a papery filling inside. – Chris.B Feb 11 at 20:10
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You have it easy, since they added the GFCIs near the panel

So they did "my trick", which is install a junction box right next to the panel and use GFCI receptacles rather than GFCI breakers. There are two reasons to do that, #1 GFCI receps are way cheaper than breakers, and possibly #2 can't get GFCIs for obsolete panels. For instance Pushmatic is the best consumer panel ever made, but no GFCIs available for it.

So with the hard part done, an AFCI upgrade is a piece of cake: Swap the GFCI recep for a GFCI+AFCI recep.

That was easy!

But before you do that, look closely at the existing "GFCIs" as you call them. The "last guy" was pretty smart, and may be way ahead of you. They may already be AFCI or AFCI+GFCI deadfronts.

By the way, they don't have to be deadfronts unless they power kitchen, bathroom or laundry room. Feel free to use plain receps there for all other circuits, just pinky-swear you won't plug - no I'm kidding. Feel free to plug in anything you want.

GFCI's provide partial arc-fault detection

Generally we're interested in 5 kinds of arc faults:

  • Arcing between hot and ground wires "parallel H-G fault"
  • Arcing between neutral and ground wires "parallel N-G fault"
  • Arcing between hot and neutral wires "parallel H-N fault"
  • Arcing in the hot wire, in series with the load
  • Arcing in the neutral wire, in series with the load

The first two, parallel arc faults to ground, are easily detected by a GFCI because they are, after all, ground faults. In fact most AFCIs detect those by having a weak GFCI detection right onboard - that's why AFCIs need neutral.

Of course it's hard to have a parallel conductor-to-ground fault if you don't have ground. Assuming you don't have ground. A lot of older wiring used metal jacketed cable, which provides varying degrees of grounding (certainly good enough to trip a GFCI)... and some uses metal conduit, which is an approved grounding method today.

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    I just realized another benefit of your scheme: if a device is causing AFCI nuisance trips, it's much easier to try swapping out for another brand of AFCI with receps than with breakers, where generally the only option other than the panel brand is maybe Eaton CLs. I'm gonna have to start doing this. – Nate S. Feb 10 at 17:46
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    @NateS yes. Use 4-11/16" square boxes with a 2-gang Decora domed cover or mud ring. They give you breathing space; 4" square boxes are very cramped for 2 devices. And I like EMT to the panel so that ticks ground off the list. – Harper - Reinstate Monica Feb 10 at 20:09
  • There's a caveat to AFCI receptacles - per NEC 210.12 the run from the breaker to the AFCI is supposed to be metal-clad cable or conduit, since that piece isn't protected against arcs. According to answer here though, this section might not apply to retrofits, only new circuits. – kg333 Feb 11 at 15:54
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    @kg333 Yeah, that only applies to new builds. For retrofits, the view is "something is better than nothing". However, the "EMT to xFCIs near the panel" technique I discuss is metal conduit, so it's good in new work also. So yeah, you can use that vintage Pushmatic in a NEC 2017 build :) – Harper - Reinstate Monica Feb 11 at 17:40
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GFCI: Ground Fault Circuit Interrupter

AFCI: Arc Fault Circuit Interrupter

They do different things. If the arc happens between the hot and ground, you're probably protected, if it's between hot and neutral, probably not. [Needs an electrician to confirm - I haven't had coffee yet this morning.]

If you're worried about arc faults in your older wiring, you'll need to update to new breakers that will protect against both (if they're made for your panel), or replace GFCI breakers with AFCI breakers, then install GFCI protection as the first device (could be the first outlet, or a "dead front" which just has the Test/Reset buttons and the electronics, but no receptacles) on each circuit that needs them.

However, I'm not clear on your statement:

they put GFCI breakers on every circuit just outside of the electrical panel

Breakers get installed inside the panel. If your electrician installed a breaker outside the panel, you'd better call your local building inspector, have him look at this installation and pull the "electrician's" license. You may also want to consult a lawyer to get your money back from said "electrician".

If the electrician installed GFCI receptacles at the first position on every outlet run, however, you're good to go. Just install AFCI breakers in the panel, and you'll have both protections.

A general precaution on putting GFCI/AFCI protection on every circuit: many appliances can cause false trips of AFCI breakers, which will lead you to resetting the breakers for no good reason. If your fridge is on a protected circuit that's busy with nuisance trips, and the breaker trips right after you leave in the morning, your fridge will be without power all day, which can be bad for the food inside. Please search this site for other tips and suggestions about this topic - there's lots of info here already.

Also, if you have an older house, you are probably critically short on circuits, so you probably can't afford (outlet wise) a dedicated circuit for the fridge to avoid the nuisance trip issue.

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  • Arcs can also be series (hot to hot / neutral to neutral - e.g. in a loose connection) - GFCI definitely won’t catch that. – nobody Feb 10 at 12:30
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    Thanks for the info. GFCI breaker wasn't the right term, from some searching it looks like they're called GFCI blank face receptacles. They are GFCIs that you can't directly plug anything into. The old wires were cut right before the panel and now connect to the GFCIs, which are then connected to the panel. – Chris.B Feb 10 at 12:31
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    @Chris.B If I correctly understand the electricians 'round here, they call that a "dead front", and that's what I was referring to. – FreeMan Feb 10 at 12:43
  • @nobody great point! If there's a loose connection, it could arc between screw & wire on the same leg of the circuit (backstabs, I'm lookin' at you!). – FreeMan Feb 10 at 12:43
  • Interesting, here fridges commonly have completely separate wiring that's not even on GFCI, it's just on a standard circuit breaker. Simiarly the lights on the corridors.That might not be within the code in the US though (I have no idea about that one, here it's completely fine). – yo' Feb 10 at 13:47

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