voltage drop wire methods

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iceman77

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I always do voltage drop on all my runs and my boss always gets mad because i use #10 on any thing over 75' on 120v because the rule of thum is #12 is good for 125' on 120v and 250' on 277v but every calculation I've done says 50' to 75' depending on the load.
Now he says that I can run 400' of #8 to all the site light and at the panel change over to #10 or #12 to connect to breaker or contactor and run for 50' as long as i don't exceed 3% voltage drop and everything i do and look at in the code says he's correct
but I feel like I've been told or read you can't do that.
and I don't do the whole run just first j-box then drop to #12
 
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Now he says that I can run 400' of #8 to all the site light and at the panel change over to #10 or #12 to connect to breaker or contactor and run for 50' as long as i don't exceed 3% voltage drop and everything i do and look at in the code says he's correct
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Your boss is correct.

You can run #12 from the breaker to a J-box or contactor, then transition to #8 and run out to the lights.

The 3% voltage drop comes from a fine print note in 210.19 and is just a recommendation and not a code requirement.

Chris
 
So long as the circuit breaker is no higher than 20 amps, you can alternate back and forth from #12 to #10 to #8 to 1000 MCM to #12 again all day long. As far as voltage drop is concerned, it will be based on how long each section of wire you have for each size, not whether the larger wire is at the begining, the middle, or the end of the run.
 
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