Downsized neutral for dryer circuit

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kwired said:
What is going to overload it when the only load is a contactor coil and maybe limited number of control relays or timers that also part of the circuit controlling the contactor coil?
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What overloads any conductor when it's sized for the expected/intended load?

Yet we still have to protect each conductor from damage.
 
LarryFine said:
Which kinda supports what I said in post #14.
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But where is any overload going to come from?

Where is overcurrent protection required for a grounded conductor? It can be permitted as long as the associated ungrounded conductors open simultaneously but is not required as a general rule.
 
winnie said:
But consider a 50A circuit that has a 20A neutral load.

You could not run a 50A branch circuit using two #8 hots a #10 EGC and #10 neutral. (Some 75C wiring method)
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Other than the exception Augie pointed out.

winnie said:
But you could run a 50A _feeder_ with 2x8-2x10.

What happens if this 50A feeder goes to a panel with a single double pole breaker in it?
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Then you have a very nice illustration of the difference between a feeder and a branch circuit, as well as how poorly the NEC sometimes handles corner cases. The branch circuit neutral will have to be upsized.

Cheers, Wayne
 
kwired said:
But where is any overload going to come from?
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Again, why then must we protect any conductor from overload?

A control wire could be subject to increased current from accidental contact to a line conductor.

Where is overcurrent protection required for a grounded conductor?
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It's usually provided by the circuit's normal OCPD, which is exactly what we're debating:

How small can it be and still be protected by the branch circuit's breaker or fuse?
 
LarryFine said:
I believe that it needs to be #10 for OCPD to protect it.
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Question: Are you taking this position because of the use of AFCI/GFCI circuit breakers and the neutral wire terminating on the breaker?
In other words, if he were to utilize #12 for the neutral, it would be in violation of 240.4(D)(5)?

Seems odd to me that prior to the use of these breakers, downsizing the neutral would be allowed, but purely because the wire is landing in a different location, that 240.4(D) now applies to neutral conductors.

SOP in my world is just utilizing the same size neutral as the ungrounded, but I do understand that in certain situations downsizing is allowed, I just rarely apply it. Seems like a waste of time to do it for one dryer circuit. How much money are you actually saving? A few dollars? Now, if you were bidding a laundromat, that would be a different story.
 
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Jerramundi said:
Question: Are you taking this position because of the use of AFCI/GFCI circuit breakers and the neutral wire terminating on the breaker?
In other words, if he were to utilize #12 for the neutral, it would be in violation of 240.4(D)(5)?

Seems odd to me that prior to the use of these breakers, downsizing the neutral would be allowed, but purely because the wire is landing in a different location, that 240.4(D) now applies to neutral conductors.

SOP in my world is just utilizing the same size neutral as the ungrounded, but I do understand that in certain situations downsizing is allowed, I just rarely apply it. Seems like a waste of time to do it for one dryer circuit. How much money are you actually saving? A few dollars? Now, if you were bidding a laundromat, that would be a different story.
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In the case of my colleague, he apparently only had #12 white on the truck, and had run out of #10 white. Sounds like he'll have to swing by and pull in some #10 white. No big deal - it was apparently something like a 30ft run.


SceneryDriver
 
SceneryDriver said:
In the case of my colleague, he apparently only had #12 white on the truck, and had run out of #10 white. Sounds like he'll have to swing by and pull in some #10 white. No big deal - it was apparently something like a 30ft run.


SceneryDriver
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A situation that I regularly enjoy mocking - guys run out of what they need and just try to push out "what's on the truck."
Happened to me a few times where the GC drops off a milk crate of old wire he had collecting dust in the garage and expects me to use it.
And now I'm the bad guy if I resist the almighty GC.

If I run out of what I need, I cope w/ the headache of having to run to the Depot or supply house. But at the same time, I get it, because it's probably why I have thousands of dollars sitting on my shelves. You gotta be smart and find a way to SAFELY utilize your backstock.

Still, ultimately, the cost per foot difference of #12 and #10 is negligible in this case. You're talking about saving $3-$5, maybe.
 
winnie said:
Remember that the neutral must have an ampacity sufficient for the load served and can be no smaller then the required EGC.

A #14 would be sufficient for the neutral load on a dryer, but the EGC on a 30A circuit is a #10, so the smallest allowed neutral is a #10.

Perhaps something that should be revisited given GFCI protection.

Jon
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Where do you get EGC on a 30A = #10 from? Isn't it #12 all the up to 60A per 250.122?
I should clarify that 250.122 is a MIN. SIZE EGC.

I think you're conflating 250.122(C) Multiple Circuits and the idea of sizing the EGC w/ the largest circuit supplied, with the OP's case of a single circuit, in which case the EGC could be sized as small as #12, I think... unless I'm misunderstanding something about the circumstances of this case.
 
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250.122 indicates circuits with overcurrent devices 21-60 amp require a #10.
(Be nice if thy actually showed it that way)
 
Not at all. If you have a Table that shows #12 is the proper EGC for a 30 amp circuit it is different from any 250.122 Table I have.
 
augie47 said:
Not at all. If you have a Table that shows #12 is the proper EGC for a 30 amp circuit it is different from any 250.122 Table I have.
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Well I guess it's a good thing that I've never undersized an EGC smaller than the ungrounded, lol.
Wth do they structure it this way. :mad:

Interesting that they allow the EGC to be smaller than the ungrounded for the larger circuits.
So we can put a #10 EGC on a 60A circuit... but for a 30A #12 would be a showstopper? Where's the logic in that?
One would think the larger the circuit, the more dangerous and thus more strict. But it appears to be more strict for the 15A and 20A ckts.
 
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Jerramundi said:
Question: Are you taking this position because of the use of AFCI/GFCI circuit breakers and the neutral wire terminating on the breaker?
In other words, if he were to utilize #12 for the neutral, it would be in violation of 240.4(D)(5)?
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No. My position has nothing to do with whether the grounded conductor lands on a breaker or bus.
 
The code used to allow smaller EGCs. In the 60's, it was common for NM cable to have an EGC a size smaller than the insulated conductors. Even in #14, #12, and #10 cables. At some point the code changed and the EGC needed to be the same size as the other conductors in 14, 12, and 10 AWG. Not sure what the issue was, but I doubt it was the copper lobby.
 
LarryFine said:
Again, why then must we protect any conductor from overload?

A control wire could be subject to increased current from accidental contact to a line conductor.


It's usually provided by the circuit's normal OCPD, which is exactly what we're debating:

How small can it be and still be protected by the branch circuit's breaker or fuse?
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If that were the reason then we wouldn't be allowed to run multiple circuits of different ratings in same raceway.

6 AWG on 50 amp breaker couldn't be in same raceway with a 20 amp circuit with a 12 AWG grounded conductor, it might accidentally contact the 12 AWG neutral.
 
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