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I am looking to buy an induction cooktop (GE Cafe CHP9536SJ). The specification sheet indicates it requires 50A service rated for 11.1 kW @ 240V. At present, there is a 40A circuit (8-2 NM-B WG) running to the existing cooktop so I need to run a new branch.

This is a drop-in unit and designed to be hard-wired. It comes with a flexible pigtail and expects me to supply a junction box for making the electrical connections. I intend to use insulated single entry splice terminals for the hot wires and a split bolt for the ground.

The installation instructions state: "You must use a two-wire, three conductor 208/240 VAC, 60 Hertz electrical system. A white (neutral) wire is not needed for this unit." So standard 240V US wiring will do and it seems that the internal electronics don't bother with 110V like older ranges so a neutral is specifically not called for. When I open the box I expect to find only three conductors coming out of the pigtail: two insulated (red/black) and one bare ground.

Given that I will run a new branch circuit (i.e., not use existing wiring) am I OK running 6-2 NM-B W/G? Is there some separate requirement that new circuits include an insulated neutral wire even if it will simply be tapped off in the junction box with the world's largest wire nut?

It's a fairly long run to the main breaker panel (60-70 ft) so there is a substantial price difference to consider plus pain of pulling less flexible cable.

  • I would recommend #6 copper wire. – Paul Logan Nov 20 '17 at 7:46
  • What does your house have now? Most houses have either nothing, or 8/3 w/ground, or 6/3 w/ground (done yay), or 6/3 no ground (in which case there's an alternative plan). – Harper Nov 21 '17 at 1:21
  • I'm asking wire, not breaker size... 40 usually means #8, but it's correct to downbreaker if you fit a range that calls for 40. – Harper Nov 21 '17 at 1:50
  • At present I have 8/2 w/ground running to a 40A breaker. – Stanwood Nov 21 '17 at 2:52
  • @Harper so it is "correct to downbreaker if you fit a range that calls for 40", but is it truly a risk if you leave in a 50-A breaker that is already there? – Jim Stewart Nov 21 '17 at 12:32
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I see no reason to include an insulated neutral. (40-years in the business.) One thing you may or may not be aware of when making the splices in the J-box behind the new range, use an over size box. And #2 use something better than a large wire nut to make the hot lead connections. Polaris makes a good splice connector. That kind of current can cause real problems with poor connections. Wire nuts were never designed to handle those kind of loads.

  • Thanks. I will order a few insulated splice terminals. Have to check they can handle the stranded wire c Ming from the appliance. – Stanwood Nov 20 '17 at 19:48
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The electrical code may require a 4-wire cable when this is redone. To save money and for more flexibility why not use (stranded) aluminum?

At some later date someone may wish to install a range/oven which requires four wires in the cable. It seems a shame to not put it in right now. The original ranges in our neighborhood of 1971 tract house were Gaffer & Sattler builder grade integrated units (cook-top, two ovens and vent hood) hard wired with heavy stranded 4-conductor aluminum cable protected by 50-A breakers.

When we replaced the original (slide-in GE range (single oven), new exhaust fan on another circuit), I put in a flush wall receptacle for the range. The new range speficies a 40-A breaker, but I just left in the original 50-A breaker.

  • If he used aluminum he would need a #4. Also, the code does not require a 4-wire for ranges. – Kris Nov 20 '17 at 14:15
  • I’ve considered that. It’s about $80 more for three-stranded. I did check and sure enough if I were to put the matching wall oven below it I would need the neutral conductor. On the bright side I just picked up the cooktop for half price. And it does have just black, red, green wires. All stranded. – Stanwood Nov 20 '17 at 19:46
  • Would the oven require it's own dedicated circuit? What breaker size is specified for the oven? The standard installation position for wall ovens is at counter top height, isn't it? – Jim Stewart Nov 20 '17 at 20:42
  • 30A. But I don’t plan to put an oven there. We have a stack of built ins on another wall and it’s more convenient that way. – Stanwood Nov 21 '17 at 2:47
  • Whether you pull a 3-wire or a 4-wire cable for the cooktop, you could install a 50-A receptacle and put a plug on the end of the the cooktop cord. Then if it has to be taken out or is ever replaced it would be simply a matter of unplugging. Of course, the receptacle would have to be located where it could be inspected to insure that the plug was fully inserted. But is it accepted standard practice to hardwire built-in ovens and cooktops? – Jim Stewart Nov 21 '17 at 10:38

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