Downsizing neutral for a range circuit.

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peter d

peter d

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About 5 years ago I installed a range receptacle in a small non-residential kitchen. I ran 3/4" EMT for it all the way and ran a #10 neutral. Now, they want to add a second range nearby and I plan on using the same conduit as running a second conduit would be a nightmare. Is there anything from stopping me from using #12 for the neutrals this time? I plan to sacrifice the #10 neutral to use as a pull wire.
 
peter d said:
About 5 years ago I installed a range receptacle in a small non-residential kitchen. I ran 3/4" EMT for it all the way and ran a #10 neutral. Now, they want to add a second range nearby and I plan on using the same conduit as running a second conduit would be a nightmare. Is there anything from stopping me from using #12 for the neutrals this time? I plan to sacrifice the #10 neutral to use as a pull wire.
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Sorry dude ...

210.19(A)(3)

Exception No.2: The neutral conductor of a 3-yVlre
branch circuit supplying a household electric range. a
wall-mounted oven, or a counter-mounted cooking unit
shall be permitted to be smaller than the ungrounded conductors
where the maximum demand of a range of 8Y4-kW
or more rating has been calculated according to Column C
of Table 220.55, but such conductor shall have an ampacity
of not less than 70 percent of the branch-circuit rating and
shall not be smaller than 10 AWG.
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iwire said:
Sorry dude ...
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I suppose the rationale for this is that if someone changes out the 240V electric range for a gas range that has 120V sparkers. Happened in my house, where the A-phase is abandoned, and the B-phase from the former 2-pole circuit and neutral supply the range. I usually leave that breaker in the OFF position and light it with a match, because the sparkers are nuisance tripping.
 
So is the following correct:

(a) There's no general prohibition on reduced size neutral conductors for branch circuits.

(b) 210.19(A)(3) says that certain branch circuit conductors "shall have an ampacity not less than the rating of the branch circuit." That requires a full sized neutral, as the neutral is a branch circuit conductor. Unless, of course, one of the exceptions applies.

In which case 210.19(A)(3) applies to "household ranges." As the OP specified a "non-residential kitchen", does that mean that 210.19(A)(3) does not apply to the OP?

That would leave the OP free to reduce the size of the neutral conductor, as long as the general requirement of 210.19(A)(1) is met: "Branch-circuit conductors shall have an ampacity not less than the maximum load to be served."

Cheers, Wayne
 
Does "household range" designate a particular type of appliance whether or not it is used in a dwelling?

May need to look into listing requirements to answer this?
 
kwired said:
Does "household range" designate a particular type of appliance whether or not it is used in a dwelling?

May need to look into listing requirements to answer this?
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I was wondering the same thing. I have seen many residential style ranges used in commercial establishments. Not restaurants but break room type of areas where usage is not that much.

The other issue is how do you determine the neutral load? I have never seen the neutral load on the nameplates or spec sheets. I guess you could review the internal wiring diagrams but this seems like a lot of work to save a few bucks on wire.
 
curt swartz said:
I was wondering the same thing. I have seen many residential style ranges used in commercial establishments. Not restaurants but break room type of areas where usage is not that much.

The other issue is how do you determine the neutral load? I have never seen the neutral load on the nameplates or spec sheets. I guess you could review the internal wiring diagrams but this seems like a lot of work to save a few bucks on wire.
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I think NEC wants 70% for worst case scenarios. I think some older ranges did use 120 volts for heating elements at times, but most ranges the past 40 years or so have just a clock or electronic controller and an oven light and that is about it for 120 volt loads. Some don't utilize the neutral at all.
 
curt swartz said:
I was wondering the same thing. I have seen many residential style ranges used in commercial establishments. Not restaurants but break room type of areas where usage is not that much.

The other issue is how do you determine the neutral load? I have never seen the neutral load on the nameplates or spec sheets. I guess you could review the internal wiring diagrams but this seems like a lot of work to save a few bucks on wire.
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I'm guessing you don't do much electrical work? It's more than saving a few bucks. It's pulling smaller wires in a raceway. It's not having to load two spools of #10 THHN onto my wire rack. It's doing what is adequate without unnecessary overkill.
 
Arent most/all ranges still able to be wired with a 3 conductor cable? Are they passing much current on the ground?

Pulling 3 more conductors thru 3/4" shouldnt be that bad, and you can always pull out the existing 3 or 4, then repull all 6 (if EMT is the EGC) or 7 (not) conductors at once.

#10 is about $0.04/foot more than #12. Even a 100' pull would be an extra $12 in wire--- how much time have you put into thinking about this vs just doing it in #10? If it's more than about 10 minutes, you're losing money even thinking about it. jmho.
 
kwired said:
That is in 215.2 and only applies to feeders, there isn't anything similar in 210 for branch circuits.
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I believe there is but I will have to look for it. Think about it.... If there is a short to neutral why would they allow a conductor smaller than the equipment grounding conductor. I don't have time right now
 
I thought there was something more specific to branch circuit but I suppose this can be used

110.10 Circuit Impedance, Short-Circuit Current Ratings,
and Other Characteristics. The overcurrent protective
devices, the total impedance, the equipment shortcircuit
current ratings, and other characteristics of the
circuit to be protected shall be selected and coordinated to
permit the circuit protective devices used to clear a fault to
do so without extensive damage to the electrical equipment
of the circuit. This fault shall be assumed to be either between
two or more of the circuit conductors or between any
circuit conductor and the equipment grounding conductor(
s) permitted in 250.118. Listed equipment applied in
accordance with their listing shall be considered to meet the
requirements of this section.
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Dennis Alwon said:
I believe there is but I will have to look for it. Think about it.... If there is a short to neutral why would they allow a conductor smaller than the equipment grounding conductor. I don't have time right now
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If you have a 15 amp circuit that has a grounded conductor and a 100 amp circuit in the same raceway, wireway, enclosure, etc. does the grounded conductor for the 15 amp circuit need to be at least the same size as the EGC required for the 100 amp circuit just in case the 100 amp circuit faults to the grounded conductor of the 15 amp circuit?

My answer is no.

For that matter the 15 amp ungrounded conductor need to be same size as EGC required for 100 circuit just in case the 100 amp circuit faults to it?

I still say no.
 
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