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I think I've made a code violation. I'm wondering how dangerous this might be. I have a 20 amp wall oven and separate 40 amp cooktop wired to the same circuit via a split bolt.

They're wired to a 60 amp breaker. The cooktop is using 6 gauge wire, but the oven is using 10 gauge wire. They join together into 4 gauge wire to the breaker box.

I'm thinking the 10 gauge wire is problematic, given the 60amp breaker. Is that the case? If so, how dangerous is it? If it were to short circuit, it would presumably only go up to 60 amps for a short period of time, right?

Any help is greatly appreciated.

Edit: Both are hardwired.

Oven model: 904.620.39 (ikea adratt)

Cooktop model: 704.620.64 (ikea samfalld)

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    Model #s of the cooktop and oven? Are either of them plug-in or are they both hardwired? (FYI, if there was a full short circuit, it would go far past 60A and trip the breaker, the problem is, for example, if the oven were to pull 40A instead of 20A, because the breaker wouldn't trip but the 10 AWG wire would overheat.) Feb 6 at 3:27
  • I added the model numbers to the description above. Both appliances are hardwired.
    – Dan
    Feb 6 at 3:42
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    You might be alright. The tap rules aren't used or allowed much in residences, except in certain cases, and range/oven separates are on the short list. You couldn't have timed your question better, a longtime poster named Ed Beal has been around a lot lately, and knows this area chapter and verse. Feb 6 at 4:26
  • Main purpose of breaker is preventing overheating and catching fire at electrical wires. Following code is important, but applying logic shows, AWG#10 is too small for 60A breaker. #6 will be better.
    – user263983
    Feb 6 at 14:08

1 Answer 1

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See NEC 210.19. are both hard wired appliance in conduit? Usually metal flex.

A 60 amp breaker would lead me to believe the person that installed this did not understand 210.19.2 they just added breakers and not actual loads.

The max size is a 50 amp circuit with a #12 awg tap see table 210.24.

I did not try and download the ikea 8mb files. But an oven on a 50 amp circuit would have a max load of 40 amps. So it is possible that the AHJ allowed this because the feeder must be able to Handel 100% of both loads. With a 60 amp breaker the feeder is oversized at #4 and #10 for a 20 amp tap would be oversized.

A standard 10’ tap rule allows the tap to be 10% of the feeder breaker so what you have is larger it could be considered safe with the exception that the 60 amp circuit is larger than allowed in this particular case. But the #10 is not unsafe under the tap rules hard wired and in a raceway (again normally metal flex).

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  • Thanks for the clarification. Makes sense. So, assuming the breaker should be downsized to 50amp, there is still an issue with the #10 tap. It runs through the wall and is only enclosed by metal flex at the subsequent junction box connecting it to the oven. Are you saying the entire length of the #10 tap should be enclosed in metal flex?
    – Dan
    Feb 6 at 19:26
  • So the metal flex is allowed and if a 50 amp breaker the wire size can be #12. I would believe the breaker should be a 50 but we need to verify the actual load value of both devices added together. The entire length should be encased from the junction box to the cooking unit. If it is not I would get a length of #12MC as this would meet code and it is available at just about every place that sells electrical supplies. As for the feed to the larger oven or whatever it is I have seen this done in non metallic as it is full size. I use metal flex Thhn, based on the load it can be as small as #8
    – Ed Beal
    Feb 6 at 20:04
  • Ah, ok. I think I have enough info to go on now. Thanks.
    – Dan
    Feb 7 at 1:28

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