Appliance grounding- Old three wire circuit

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T-Wragg

Senior Member
Location
Paradise, California, USA
Occupation
Electrical Contractor
Recently during a remodel I installed a new service in another location and changed the existing service to a new four wire sub-panel. The existing range circuit is 3-wire SE service entrance cable. Am I violating any code or creating a safety issue by reuseing this circuit and connecting the bare wire to the neutral buss of the new sub-panel. Thank you for your reply.
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
Re: Appliance grounding- Old three wire circuit

Yes, it would be a violation. 310.2(A): Conductors shall be insulated, unless permitted elsewhere. Nowhere else does it say that a neutral can be bare copper. 200.6 gives the required covering and color codes for neutral wires.
 

jwelectric

Senior Member
Location
North Carolina
Re: Appliance grounding- Old three wire circuit

Just for you Kturner :)

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 grounded 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 grounded to the grounded circuit conductor if all the following conditions are met.
(1) The supply circuit is 120/240-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 of receptacles furnished as part of the equipment are bonded to the equipment.
:)

[ September 27, 2005, 04:29 PM: Message edited by: jwelectric ]
 

T-Wragg

Senior Member
Location
Paradise, California, USA
Occupation
Electrical Contractor
Re: Appliance grounding- Old three wire circuit

I had referred to 250-140 exceptions before I posted and I think that I'm within code. If I am interpreting something wrong please let me know.
 

magoo66

Member
Re: Appliance grounding- Old three wire circuit

(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

Wouldn't this prohibit the installation?
 

electricman2

Senior Member
Location
North Carolina
Occupation
Retired Electrical Contractor
Re: Appliance grounding- Old three wire circuit

Originally posted by magoo66:
(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

Wouldn't this prohibit the installation?
Yes. It no longer meets the conditions of the exception.
 

stud696981

Senior Member
Re: Appliance grounding- Old three wire circuit

I agree, since the panel is now a sub-panel, not service equipment, then it has to be upgraded to a 4 wire installation.
 

T-Wragg

Senior Member
Location
Paradise, California, USA
Occupation
Electrical Contractor
Re: Appliance grounding- Old three wire circuit

Thank you for your responses. I wasn't sure if my application violated exception # 3. I will change it to a four wire circuit.
 

jes25

Senior Member
Location
Midwest
Re: Appliance grounding- Old three wire circuit

On a related subject. what grounds the metal of the 3 wire receptacle itself. The neutral may be used on the range case of an exist intall but not the recp itself?
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
Re: Appliance grounding- Old three wire circuit

The receptacles I have at home (range and dryer) look like they are plastic (no external metal parts that I can see).
 

jes25

Senior Member
Location
Midwest
Re: Appliance grounding- Old three wire circuit

The pass and seymour ones I use have a metal back and a 10-32 hole that says gnd by it. This metal in not exposed if it is up against the wall. I think all recp. have a metal back.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Re: Appliance grounding- Old three wire circuit

On a semi-related subject, last year, I installed an ATS where I had to place a main disconnect ahead of the ATS. I added a grounding bus to the panel and relocated all the EGC's to it, and removed the panel bond.

The range and dryer were wired with aluminum SE cable, as was common practice then, and they were run throug a part of the house that was impossible to rewire through: a breezeway that was later enclosed.

The "attic" space above the converted reezeway was not accessible from either the garage (where the panel was), nor the house, because that space was single-story height and the rest of the house was two floors.

I spoke with the inspector beforrhand, and he agreed with my suggestion that I wrap the SE cables' bare conductors with white tape from the sheath to the neutral bus, and not the grounding bus.

Our combined reasoning was that using the neutral for grounding was better than using the EGC as a neutral, since both appliances have line-to-neutral loads, like motors, timers, lights, etc.

It was a pleasure collaborating with "the other side" instead of clashing. I've never really had any problem with any inspector because we're always respectful, and it always turns out that one of us or the other is correct.
 
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