Conductor size for voltage drop.

[Daniel621]

I am a master electrician with 30 years experience + 2 years experience as an electrical inspector here in New York. I'm well aware of a voltage drop calculations but we only ran into a project where the contractor ran #10 conductors on a 15 amp circuit for 3 air conditioning blowers. He then tapped off the #10 in the junction box and ran #12 the end 40 ft to the unit disconnect. The system is fused at 20 amps, the 10 wire was for voltage drop consideration. Should the entire run be number 10 or is the reduced wire size at the end permissible. I do not see a clear in the code.

 

[charlie b]

There is no requirement to keep the same wire size for the entire run. What matters is that every section of wire is protected against overcurrent by the upstream overcurrent device. The #12 section of wire will be adequately protected by the upstream 20 amp breaker. So all is well.

Welcome to the forum.

 

[infinity]

As Charlie stated it fine because you have #12 conductors and a 20 amp OCPD. I would hesitate to use the word tapped since you actually have a splice not a tap.

Welcome to the Forum.