Electric Cooktop 3-Wire Connection

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MAD King

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Location
Nashville, TN
Hello,

grat that such a forum exist and that I was able to find it.

I am fighting with a few guys about the NEC code which allows to mount the ground from a electrical cooktop to the neutral when only a 2 connector and ground available.

Can you guys give me some clarification on this?

This is what's coming out the wall

Wires.jpg

And that's what's on the cooktop.

Wire2.jpg

Braker has 50amps.



Thank you
 
C

conmgt

Senior Member
Location
2 Phase Philly
The cooktop lead has three conductors, two hots and a ground, no neutral in sight. The cable in the wall has three conductors, two hots and a white wire.
 
Dennis Alwon

Dennis Alwon

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Location
Chapel Hill, NC
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Retired Electrical Contractor
Any new installation will require a 4 wire connection to the range however an existing branch circuit may be used if you replace the range.
 
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conmgt

Senior Member
Location
2 Phase Philly
jumper said:
What? You are bonding the frame to a neutral in this case, re-identification as an EGC would be a violation IMO.
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If the other end of the cable ends in the service panel, no difference if its used as a neutral or grounding conductor, just make it green. If it ends in a subpanel, you'd need to move it to the GND bar and make it green.
 
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hurk27

Senior Member
Location
Portage, Indiana NEC: 2008
jumper said:
What? You are bonding the frame to a neutral in this case, re-identification as an EGC would be a violation IMO.
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Since the cook top is a 240 volt only appliance and has no need for the neutral 250.119(B) will allow the white neutral to be re-identified with green tap as an EGC at both this receptacle and at the panel, if this wire is ran from a sub-panel then it will have to be moved from the neutral bar to the grounding bar.

Also since the wiring method to the receptacle is NM there is no restriction on wire sizes as there is for single conductors in a raceway in 250.119(A)

To the OP:
One problem I see is the whip on this cook top is designed for hard wired and the photo shows a receptacle, this would have to be addressed by your electrician.
 
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conmgt

Senior Member
Location
2 Phase Philly
I've been assuming that the receptacle would be removed and a box installed.

What are the other parts of the code concerning re-identifying conductors other than 250.119?
 
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GoldDigger

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Placerville, CA, USA
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conmgt said:
I've been assuming that the receptacle would be removed and a box installed.
...
What are the other parts of the code concerning re-identifying conductors other than 250.119?
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There is no need to re-identify, IMHO. The white wire is the grounded circuit conductor. It remains the grounded circuit conductor, and as such it needs to be terminated at the neutral bar at the supply end.
You are simply allowed by 250.140 to connect the frame ground (green wire) of the range to it.

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 ....
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The details of the exception even allow the range to contain 120 volt receptacles which have their neutral bonded to the frame. I suspect that the range in question does not have receptacles, since it has only a green and no white wire at its end, but it would still be OK if it had them.

This was already explained by jumper, but maybe not everyone read the referenced code section.
 
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H

hurk27

Senior Member
Location
Portage, Indiana NEC: 2008
conmgt said:
I've been assuming that the receptacle would be removed and a box installed.

What are the other parts of the code concerning re-identifying conductors other than 250.119?
Click to expand...

The only other requirements is for the grounded conductor (neutral) which is 200.6 which has the same allowance for identifying another conductor as a neutral, but since he is changing a neutral to a grounding conductor then it doesn't apply in this case.

While it looks like a white can be re-identified as a grounding or ungrounded conductor, a green conductor can not be:

250.119 Identification of Equipment Grounding Conductors.
Unless required elsewhere in this Code, equipment
grounding conductors shall be permitted to be bare,
covered, or insulated. Individually covered or insulated
equipment grounding conductors shall have a continuous
outer finish that is either green or green with one or more
yellow stripes except as permitted in this section. Conductors
with insulation or individual covering that is green,
green with one or more yellow stripes, or otherwise identified
as permitted by this section shall not be used for ungrounded
or grounded circuit conductors.
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While I have always been allowed to use a re-identified white for a grounding conductor,I did have an inspector I had to get the state to over ride him as 200.7(C)(1) does seems to say it can be re-identified as an ungrounded conductor but not a grounding conductor:

(C) Circuits of 50 Volts or More. The use of insulation
that is white or gray or that has three continuous white
stripes for other than a grounded conductor for circuits
of 50 volts or more shall be permitted only as in (1)
through (3).
(1) If part of a cable assembly and where the insulation is
permanently re-identified to indicate its use as an ungrounded
conductor, by painting or other effective
means at its termination, and at each location where the conductor is visible and accessible. Identification shall
encircle the insulation and shall be a color other than
white, gray, or green.
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Why does it list White and Gray along with Green unless this is only addressing if it is used as an ungrounded conductor which would make sense as these colors are not allowed to be used for ungrounded conductors, and our state AHJ agreed with this interpretation and there is no where else that disallows a white conductor to be re-identified as a ungrounded or grounding conductor like it does for a green conductor in 250.119.
 
Little Bill

Little Bill

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Tennessee NEC:2017
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Semi-Retired Electrician
MAD King said:
hurk27, you confused me with your last posting.
Can I mount the ground wire from the cooktop to the neutral on the receptacle?
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First, it appears the cook top is meant to be hardwired. All I have ever installed had a flexible whip from them that had to be hardwired to a box.
You would need to remove the receptacle and use the box as a junction box, then hard wire the cook top.

You can connect the bare from the cook top to the neutral (white) from the receptacle box but you need to tape the white wire green. Also as has been stated, if the feed is from a sub panel, you need to move the white wire to the ground bar and also tape it green.
 
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