Hi,

I have a question that's not related to woodworking, but could apply to shop wiring for a wood-working machine needing both 120 and 240 volt single-phase power.

I'm considering replacing an old gas range with a new dual-fuel range, using gas for the stove top and electricity for heating the oven. The stove manufacturer specifies a 4 wire outlet (two hots, a neutral and a ground). My understanding is that the current NEC requires separate neutral and ground wires for all stove installations, though in the past the NEC may have allowed a common neutral/ground wire in stove installations (3-wire NM).

I have an existing (but not currently used) stove circuit with double 50 amp circuit breakers and NM wire (6-6-G). The circuit length (one way) is about 60'.

I am considering converting the current 3-wire circuit into a 4-wire circuit by ending the current 6-6-G wire in an appropriately-sized box and running a new 14 gauge NM wire from the service panel to this new box. The hot 14 gauge wire would not be connected to anything in the service panel or the new box. It would just have a wire nut covering the wire at each end. The 14 ga neutral would be connected to the service panel neutral bus. Within the new box the two 6 hots and ground would connect to the two 6 hots and ground of a new NM 4-wire. The new 14 ga NM neutral would connect with the neutral of the new NM 4-wire in the box. The new NM 4-wire would go to a new 4-wire stove outlet to which the new stove plug would be plugged in.

The 120 volt load of the stove for the oven light, gas burner ignitors, and control panel can easily be handled by the 14 ga neutral. The 240 volts is only used by the oven heating element.

My question is "would this system violate the current NEC"? If "yes" what aspect of the NEC does it violate? I'm trying to avoid the cost and effort of running a new 4 wire NM cable from the service panel to the stove outlet. If what I have described violates the current NEC, can you propose another option that would allow me to use the existing 6-6-G wire for most of the run to the stove before it connects to a new 4-wire NM cable going to the stove outlet? For example, if using only the neutral wire in the new 14 ga NM cable violates the NEC, could I run just a single 14 ga wire in conduit from the service panel to the new box instead of running the new NM 14 ga cable?

All this wiring is easily accessible in my basement. Only the last 1-2' or so of the new 4-wire NM would go through the first floor subfloor to the new stove outlet.

Thanks.

Bob