Absurdly Simple Question

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George Stolz

George Stolz

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Hospital Master Electrician
Suppose you have a 10A load on a dedicated 20A circuit. Can you install a 12 ungrounded and a 14 grounded conductor?

A guy put this question to me, I've been running laps trying to come to a decent answer.
 
George you answered your own question, "on a dedicated 20A circuit...." 14 is not allowed to be fused at 20A, assuming this is a standard load and not Art. 440 exception.
 
send him to the wire chart and he will see that #14 can not be used for higher than 15 amps for most circuits. If his load is truly fixed then install 15 amp breaker.
Does no good to have #12 hot and #14 neutral. Smallest wire determines the breaker size.
Be carefull around this guy as his thinking could kill
 
in the 2008 NEC HANDBOOK Look at 310.15(B)(4)(c) and read the comments then 210.19(A)(1) and the comments.
 
LEO2854 said:
in the 2008 NEC HANDBOOK Look at 310.15(B)(4)(c) and read the comments then 210.19(A)(1) and the comments.
Click to expand...

In George's example there are only 2 conductors and harmonics are not part of the issue on a 2 wire circuit, So 310.15(B)(4)(c) is not applicable.
Also the load is 10 amps well below the 125% required by 210.19(A)(1) what does apply is 240.4(D)(3)
 
acrwc10 said:
In George's example there are only 2 conductors and harmonics are not part of the issue on a 2 wire circuit, So 310.15(B)(4)(c) is not applicable.
Also the load is 10 amps well below the 125% required by 210.19(A)(1) what does apply is 240.4(D)(3)
Click to expand...

acrwc10
Thanks for you ref to 240.4(D)(3) I know George's example had nothing to do with harmonics. if you read through the commets after 310.15(B)(4)(c) you will see that it leeds to other articles ref the Grounded conductor.

if you look at 210.19(A)(1) Exception # 2
 
George Stolz said:
Suppose you have a 10A load on a dedicated 20A circuit. Can you install a 12 ungrounded and a 14 grounded conductor?

A guy put this question to me, I've been running laps trying to come to a decent answer.
Click to expand...

I say yes because of 210.19 (A)(4) & possibly except. 2 of 210.19(A)(1) but hopefully with my proposal this will be cleared up.

Read this thread and make your decision.
 
iwire said:
240.4(D) says no for most applications.
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Bob.
Grounded conductors generally are not connected to an overcurrent device. If a branch circuit grounded conductor makes contact with an equipment ground conductor and/or a grounded surface, the circuit breaker/fuse for that circuit will not open. Therefore groundfault current does not flow on the grounded conductor.

210.19(A)(1) ex#2 permits the grounded conductor to be sized differently than in the past (before 2008 NEC).
The answer to this question would be yes. I really do not see the issue, we downsize service and feeder grounded conductors.
 
Pierre C Belarge said:
Bob.
Grounded conductors generally are not connected to an overcurrent device. If a branch circuit grounded conductor makes contact with an equipment ground conductor and/or a grounded surface, the circuit breaker/fuse for that circuit will not open. Therefore groundfault current does not flow on the grounded conductor.

210.19(A)(1) ex#2 permits the grounded conductor to be sized differently than in the past (before 2008 NEC).
The answer to this question would be yes. I really do not see the issue, we downsize service and feeder grounded conductors.
Click to expand...
The problem is then the neutral is smaller then the egc. This seems counter to what we know throughout the code.
 
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