Branch circuits

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infinity

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New Jersey
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Journeyman Electrician
Potential voltage drop or if in a raceway usually for derating. For #12 THHN you can only get 9 CCC's in a raceway before the derating drops you below 20 amps. For #10 THHN you can get up to 20 CCC's with a 50% derating factor and still have a 20 amp conductor.
 

vortiz.08

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Location
Dallas Texas
So if I have a 3/4 home run with #12 4 hots and 4 neutrals and each circuit is feeding 4-5 plugs plus 2 lights on a 20 amp breaker 120/240 system would I be okay
 

Strathead

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Location
Ocala, Florida, USA
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Electrician/Estimator/Project Manager/Superintendent
So if I have a 3/4 home run with #12 4 hots and 4 neutrals and each circuit is feeding 4-5 plugs plus 2 lights on a 20 amp breaker 120/240 system would I be okay

For clarification, you didn't state the distance, or what is expected to be plugged in (amperage on the circuits). Voltage drop is not a code requirement of the NEC. It is in my state, Florida. In that case, #12 may not be OK if the distance and the amperage creates a voltage drop over 3%.
 

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
In our project we instruct the contractor where ever the length is exceed 30 meter to go for 6mm2 (#10) so voltage drop will not go beyond 2.5%

I see that too. It is a reasonable rule of thumb, but it is too arbitrary. A high amperage load will need to be shorter, but most loads can go far beyond the 100 feet before hitting the 2.5% or 3%, so that just drives up the job cost.
 
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