Basic Question about Voltage/Drop wire sizing in house

[mcamuto]

Hi -

I am new here after getting referred from a few places. This is more very 'basic' question looking for a 'basic answer'.

Can somebody explain to me the concepts around voltage drop and length of wires for residential houses. I read a lot of places that if the length from breaker panel to any load is over 50 you should drop the breaker down a notch.

For example, in my house (and most of my friends houses) I see 12 gauge wire coming from the circuit breaker to say power kitchen outlets. The length of of the main run (in conduit) is say 40 feet but then after you branch out you add another 15 of wire because its on the 2nd floor. So ultimately its 55 feet to that outlet. However these circuits are on 20 amp breakers. Is this acceptable or should they be dropped to 15 amp circuits for 12 gauge wire. I see a lot of places in like 3 story houses where 12 gauge is used with 20 am breaker and was just curious on the 'theory' around voltage drop and 14,12,10 gauge wire.

For example I also have ceiling lights with really long length of wire on 14 gauge, is it worth just dropping to a 10 amp breaker 'to be safe' so to speak??

Thanks in advance.

m

 

[charlie b]

First of all, you have been completely misinformed. We do not drop the rating of a breaker, if we are concerned about the length of a wire or are concerned about voltage drop. We might upsize the wire, and keep the same breaker size, or we might leave things alone.

That said, I am closing this thread, in accordance with the Forum?s rules. This Forum is for professional electricians, inspectors, engineers, and other members of the electrical industry. We are not permitted to provide ?how-to? assistance to a person who is not employed in this industry.