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I want to tap my electric oven's existing circuit to add a NEMA 6-15 outlet in my kitchen for a 240v kettle (the oven is rated at 21 amps and the breaker is 40 amps, so I think I should be OK adding my 12amp kettle.)

My understanding is that since it is 240v, I'm not required to have GFCI protection on that outlet but since it is a) in a kitchen, b 24" from my sink c) I'm plugging a kettle full of water into it, I'd feel a lot safer, especially at that voltage, if it was on a GFCI. As far as I know, my only option at 240v is a GFCI breaker rather than at the receptacle.

So, is there any downside (other than cost) to just swapping the whole 40 amp breaker for a GFCI breaker and running my electric oven on a GFCI all the time?

EDIT: to clarify, here's what I'm picturing and my current breaker box. The first electrician I talked to already pointed out the oven's current breaker is mis-matched and should be replaced with GE breaker. He said he could do it, but said something like "you sure you want to run the stove [oven] on the GFI?" which made me wonder if there was some downside to that?

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    The "special rules for ovens" which bless some funny business with circuit sizing don't cover putting 15A receptacles on a 40a breaker, so stop now and run new wire, or install a sub-panel with a 15A breaker and a 40A breaker. A failure in your kettle would get spectacular without getting to the point of blowing that 40A breaker. – Ecnerwal Oct 2 '20 at 2:07
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    Is putting a subpanel in your kitchen an option? I take it your cooktop is on a separate circuit altogether, for that matter? – ThreePhaseEel Oct 2 '20 at 2:11
  • Seems like we have two questions here: "can I use GFCI on the oven circuit?" and "how can I get a 6-15 receptacle into the kitchen?" For the latter, investigate whether your kitchen has any multi-wire branch circuits. The easiest way to detect this is to check your circuit breaker panel for 20A handle-tied breakers that feed kitchen outlets. – Greg Hill Oct 2 '20 at 2:21
  • @Ecnerwal running new wire from the panel will need to wait for a gut renovation, since it's an old apartment so will need to rip up the walls to do that. – David Oct 2 '20 at 2:44
  • @GregHill the oven's 2-pole is the only handle-tied breaker in the panel. – David Oct 2 '20 at 2:50
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Can't put a 15/20A recep on a 40A breaker

Any device in there would have, effectively, no circuit breaker protection at all. Because the 40A breaker would be so far above likely practical short-out currents that it would not notice if the appliance burst into flame. Rulewise:

  • 210.21(b)(3) says on a 40A circuit, only 40A or 50A receps can be used. (because NEMA never defined a standard for a 40A recep). It also says 15A receps can only be used on 15A and 20A circuits.

  • Next, 210.21(B)(2) says the recep loads can't exceed 80% of circuit ampacity.

  • Another rule says you can't have any receptacles at all on a circuit with hardwired loads making up more than 50% of breaker capacity.

Wait. Isn't the GFCI a circuit breaker too?

Nope. Actually the very opposite: 15A GFCIs are designed by the factory to safely allow 20 amps of passthrough - that's a UL requirement because 15A receps are allowed on 20A circuits. So in reality, the GFCI has no idea what current is coming through it (only current difference) and will carry an overload right up until the point it bursts into flame. GFCIs (and breakers for that matter) are not magic everything-fixers.

Your best bet is probably run a new kitchen circuit

One option is a multi-wire branch circuit. (MWBC). That is a cable with 2 hots and a shared neutral. I see at least 2 red wires in that panel, so it's possible you already have a kitchen MWBC, that would be neat because you could just convert it. But troublingly, it does not have handle-tied breakers. On a GE panel, even that is not enough; any MWBC must use a 2-pole breaker! (part of the reason for handle-ties is that forces the breakers onto opposite poles, an essential MWBC requirement; but that doesn't work in GE's half-width breaker design. Only a 2-pole breaker is keyed/notched to only fit where it belongs.)

With the MWBC, you can put both 120V and 240V sockets on it. One company even makes a combo 120/240V socket - one of each on a common-shaped duplex receptacle!

So if there isn't a kitchen MWBC, you could run one. That will give you both additional 120V outlets and also 240V outlet(s). This MWBC could replace your existing kitchen circuits if they are 20A breakered.

As far as GFCI, I don't see a sink nearby. Unless the latest Code requires it, you may be able to dodge the GFCI requirement. If you must go GFCI, it must be at the breaker. Definitely do the MWBC and definitely go 20A with multiple recep sockets, since you're sinking a lot of coin into that, so might as well get maximum bang for the buck.

That panel has serious issues

Somehow the panel's dead-front has disappeared. I don't understand how that's possible, but what should not be possible is for curious fingers to touch any of the panel guts... or for that matter, for an arcing fire inside the panel to get out of the panel through gaping holes in the front cover.

I would talk to a GE dealer about getting the correct dead-front for that panel. If that is not feasible, that panel is *grossly under-sized) for a house, so maybe it's time to replace it with a 40-space panel.

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  • Would a reasonable option be to run from an existing 15/20a breaker to the desired outlet location and put a GFCI receptacle there instead of a GFCI breaker? (Or is that what you're saying in your 2nd major point and I'm just missing it?) – FreeMan Oct 2 '20 at 16:59
  • @FreeMan Sure, if you can tap the MWBC legally and can find a 240V GFCI recep. – Harper - Reinstate Monica Oct 2 '20 at 17:09
  • Thanks! I could put a 40A recep in though? I'm putting my own cord on the kettle (and it has its own 13A fuse) so can do that if it'd meet the rules. The sink is just left of frame, plus when I run my brew kettle there's a pump that's be a few inches away, so very much in "could get wet" territory so legal requirement or not, I'd want a GFCI for peace of mind. Running new wires to the panel is unfortunately not an option since it is an old apartment and doing so would require ripping up all the walls to the panel. Panel size is probably because it's a > 100 yr old apartment. – David Oct 2 '20 at 18:18
  • if running new wires is a non-option, and I don't have MWBC, am I just out of luck? can I tap the oven but put a downstream sub panel inside the cabinet with a 20a gfci breaker in it? – David Oct 2 '20 at 18:39
  • @David -- can you post photos of the inside of the range receptacle's box please? That'll be quite important when it comes to determining your actual options here – ThreePhaseEel Oct 3 '20 at 0:36

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