3 Wire Cooktop with 6/3 Service

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Old 08-19-13, 06:09 AM
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3 Wire Cooktop with 6/3 Service

Apologies if this has been answered but after reading other threads, I can't find one clear position on the solution. I am installing a new GE Induction cooktop which calls for 50 amp service. Old wiring was not of sufficient gauge so I pulled the recommended (required?) 6/3 NMB cable from the box to the appliance location and bought a 50 amp breaker. Cooktop only has 3 wires: red, black and green, while the new 6/3 cable of course has 3+ ground.

The wiring diagram included with the appliance is very unclear, but it appears to show white (neutral) connected together with the bare ground wire from the panel, both joined with the green ground wire from the appliance pigtail. It seems some opinions state that bonding these together is not allowable, and would create an unsafe situation. Others state that the acceptable way to do this is to just cap off the white neutral wire in the service panel and in the junction box. Incidentally, service is from my main panel where neutral and ground are all on one bus.

Which is correct? Tie both neutral and ground from the box to the appliance ground and also ground to the metal junction box? Or, cap off white neutral wire at both ends and leave it unused?

By the way, I bought split bolts connectors to ensure good safe connections. However, if neutral and ground need to be connected with ground from the appliance pigtail, what is best connector and method to accommodate joining these 3 wires?

Thanks in advance!
 

Last edited by Newbie10; 08-19-13 at 06:11 AM. Reason: Spelling
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Old 08-19-13, 07:43 AM
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Which is correct? Tie both neutral and ground from the box to the appliance ground and also ground to the metal junction box? Or, cap off white neutral wire at both ends and leave it unused?
Correct would be to not use the white neutral conductor, cap it off at both ends. Connect the green ground from appliance to bare ground in NM B cable. If the box is metal, loop the bare ground around a green grounding screw in the back of the box before connecting it to the appliance green ground wire.
 
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Old 08-19-13, 05:17 PM
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Roger that!

Thanks for the response. Makes sense to me. What doesn't seem sensible is code requirement to run 4 wire on new 220 branch circuit even if you'll only use 3. You end up with a neutral wire just hanging out at both ends. Anyway...
 
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Old 08-19-13, 05:21 PM
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Many new ranges, cooktops and ovens have 120 VAC components in them that require a neutral.
You may not be using that neutral now but you might in the future.

You will only need to tape the two hot bugs. The ground one can remain bare.
 
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Old 08-19-13, 06:56 PM
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What doesn't seem sensible is code requirement to run 4 wire on new 220 branch circuit even if you'll only use 3. You end up with a neutral wire just hanging out at both ends.
First of all, it's not a 220 branch circuit, it's a 240 volt branch circuit. In your application a 4-wire circuit isn't required by code, but common sense tells us that not all cooktops or ranges or ovens work on a 240 volt circuit. Many require 120/240 volt circuits and require that 4th white neutral conductor like PJ mentioned and it just makes sense to always run the 4-wire circuit for future.
 
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Old 08-21-13, 08:18 AM
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Slightly different approach used

Thanks again for your responses. Had an electrician in just to make sure things were up to snuff. He recommended for ease of access that we put in a surface mount 240v receptacle (it's inside an island cabinet under the cooktop) and attach a 3 prong plug to the pigtail on the cooktop. We capped off the neutral wire in the panel and in the outlet box. It works and hopefully is acceptable from a compliance and safety perspective.
 
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