Repurpose 240V range circuit

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solarken

NABCEP PVIP
Location
Hudson, OH, USA
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Solar Design and Installation Professional
I have a single family building where the old 240V 30A electric cooktop is being replaced with a gas cooktop with 120V cord for the ignitor. The existing feeder is 6AWG NM with neutral and ground, and it is run to a metal box in the back of the kitchen cabinet, and the range outlet is wired from the box. This is an older house with the main panel embedded in a wall in a stairwell, with no easy access without drywall work. The easiest solution would be to remove the range outlet, and wire a 120V outlet off L1 and Neutral of the existing feeder, replace the 2-pole breaker with a single pole 20A, and cap off the L2 conductor. Has anyone done this before? I don't see an obvious code violation. Thanks.
 
EGC would be too small per how things are worded in NEC, reality in most cases is it would still be sufficient. Would need to be a pretty long run for it to not be sufficient, IMO. Long enough that the initial installation likely would have ended up being even larger conductor size than what it is.
 
xformer said:
Why not use the other #6 as an EGC?
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The issue with that is how would you connect it to the receptacle. Splice a piece of #10 and there we go again another violation. As stated above, I would have no trouble using the existing equipment grounding conductor.
 
solarken said:
I have a single family building where the old 240V 30A electric cooktop is being replaced with a gas cooktop with 120V cord for the ignitor. The existing feeder is 6AWG NM with neutral and ground, and it is run to a metal box in the back of the kitchen cabinet, and the range outlet is wired from the box. This is an older house with the main panel embedded in a wall in a stairwell, with no easy access without drywall work. The easiest solution would be to remove the range outlet, and wire a 120V outlet off L1 and Neutral of the existing feeder, replace the 2-pole breaker with a single pole 20A, and cap off the L2 conductor. Has anyone done this before? I don't see an obvious code violation. Thanks.
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I do not understand the issue with the EGC. #6 NM has a #10 EGC? That is not sufficient for 20 amps?
 
xformer said:
OP stated he was switching to a gas cooktop and would just need a 120V Ckt. :)
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Yes, I was asking for details of the existing circuit.

In my home, the gas range has a 50A 240V 14-50 receptacle, adapted to 120V 5-15 using an off the shelf adapter. No fuss with changing the circuit; the circuit remains available for changing back to electric in the future, and I've had no problems with this approach.

But I've only seen the proper sort of adapter (with an internal fuse) for 14-50 receptacles.

-Jon
 
Greg1707 said:
I do not understand the issue with the EGC. #6 NM has a #10 EGC? That is not sufficient for 20 amps?
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The requirement that if the circuit conductors are 'increased in size' the EGC must be correspondingly increased.

If you install a 20A circuit with #6 circuit conductors, you are required to install a #6 EGC.

IMHO in this particular case this is an un-necessarily technicality. In the other recent thread on the topic, an interesting code interpretation got around the problem.

-Jon
 
Greg1707 said:
I do not understand the issue with the EGC. #6 NM has a #10 EGC? That is not sufficient for 20 amps?
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The issue is section 250.122(B) which states if you increase the conductor size then the equipment grounding conductor would need to be increased proportionately.

#12 has a #12 equipment grounding conductor
Increase to #6
Equipment grounding conductor must also increase proportionately
Increase to #6
 
winnie said:
In the other recent thread on the topic, an interesting code interpretation got around the problem.
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Right. Does decreasing the breaker size equate to increasing the conductor size.?

For this discussion, I say no, it does not.

A raised cover and a receptacle, three pigtails, four wirenuts, and you're done.

Oh, and a 1p breaker and a filler.
 
LarryFine said:
Despite the technicalities, I have done it many times, and will do so again.

Also, SE cable has been used more than NM for cooking equipment here.
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SE cable was fine back when we could bond the appliance frame to the grounded conductor. We mostly used SE cable before the change for ranges, though typically used 10-3 (no ground) NM cable for dryers, suppose SE cable maybe not commonly available that small? It was used on really old farm buildings, like the 1940's and 50's for service cable quite often. Even a "coaxial type with just one insulated and a concentric bare for when you only had 120 volt supply at some those outbuildings.
 
It’s understandable for voltage drop issue to increase the EGC.
other than that ,when else would be a good idea when increasing conductor size to also increase the egc?
250.122(b) should state for voltage drop.

In my mind if it’s good for 40/50 amps why not for 20, just dump.
 
This is a situation that illustrates the downsides of a prescriptive code such as the NEC, as opposed to to a performance code where sound design practice can be used-it can't cover every possibility. The conversion of a circuit like this is done all the time and perfectly safe. I would never fail this as long as the slices are proper (likely CU to AL).
 
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