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I am connecting a double oven that has a 10 gauge 4 wire cable coming out of back to a 10 gauge 3 wire cable that runs to the main panel.

How should I accomplish this?

  • What make and model is the double oven? Is this 3 wire circuit running to the main panel or to a subpanel? What is this 3 wire circuit run using? Can you provide photos of the receptacle/junction box's insides? – ThreePhaseEel Jul 29 '17 at 0:18
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    The 4-wire cord is the modern, safe wiring method. The 3-wire socket has omitted the ground wire, which makes it dangerous if certain types of failure occur. Your best bet is retrofit a ground wire and upgrade the socket to 4-prong. – Harper - Reinstate Monica Jul 29 '17 at 0:57
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    3 wire is still allowed by code, the house doesn't have to be rewired. Funny thing I have never known anyone to be electrocuted by a 3 wire range and they were code for 50+ years. I have updated a few homes but that was because of a remodel or the panel within just a few feet. – Ed Beal Jul 29 '17 at 2:21
  • But if you decide to go from 4-wire to the 3-wire cable to the panel you connect the ground wire to the neutral wire and connect this to the neutral wire in the receptacle. When you say you have a 3-wire cable from the receptacle to the panel you must have the two hots (each 120 V from gnd and neutral and 180 deg out of phase from each other) and an insulated (usually white) neutral. – Jim Stewart Jul 29 '17 at 2:25
  • +1 to Ed Especially with a built-in oven there is really no safety difference between the 3-wire or 4-wire method. The NEC is just trying to be consistent. A receptacle is not usually used with a built-in oven. Technically the two hot legs are not 180 degrees out of phase with each other. They are the same phase. The 3-wire could be SE cable and could have a bare neutral. – ArchonOSX Jul 29 '17 at 9:09
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The National Electrical Code allows an existing 3 wire cable to feed a new oven.

Here is the pertinent article from the 2014 NEC:

250.140 Frames of Ranges and Clothes Dryers. Frames of electric ranges, wall-mounted ovens, counter-mounted cooking units, clothes dryers, and outlet or junction boxes that are part of the circuit for these appliances shall be connected to the equipment grounding conductor in the manner specified by 250.134 or 250.138.

Exception: For existing branch-circuit installations only where an equipment grounding conductor is not present in the outlet or junction box, the frames of electric ranges, wall-mounted ovens, counter-mounted cooking units, clothes dryers, and outlet or junction boxes that are part of the circuit for these appliances shall be permitted to be connected to the grounded circuit conductor if all the following conditions are met.

(1) The supply circuit is 1201240-volt, single-phase, 3-wire; or 208Y/120-volt derived from a 3-phase, 4-wire, wye-connected system.

(2) The grounded conductor is not smaller than 10 AWG copper or 8 AWG aluminum.

(3) The grounded conductor is insulated, or the grounded conductor is uninsulated and part of a Type SE service-entrance cable and the branch circuit originates at the service equipment.

(4) Grounding contacts receptacles furnished as part of the equipment are bonded to the equipment.

If all of 1-4 are true you can do it.

The oven should have a bond strap from the manufacturer to allow the bonding of the neutral and ground on the oven. And then you can connect both the ground and neutral from the oven to the neutral wire from the 3-wire cable.

Good luck and stay safe!

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