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Am I going to have a problem with voltage drop or heat?

Posted by jca1 (My Page) on
Thu, Jun 2, 11 at 21:42

Hi, first post in a while, need some help from any electricians on board.

I have an outdoor building 12x12. It has been converted to an outdoor kitchen. There is a sub panel fed by a 60amp breaker and 6AWG copper THHW conductors(4) in PVC conduit from my main panel in our house, 160' away. Now all of a sudden I have the following loads:

8000 BTU window AC (new unit) 7amps
1 stand mixers 2.7 amps
one small drink cooler/fridge thing 2.5amps
a small microwave that would only be used on occasion
and now a 16amp electric oven (240Vac)

For a total of approx 40 amps not figuring any LRC on the AC and fridge.

Best I can tell voltage drop for 6AWG at 60 amps for that distance would be a shade over 3%

Is this going to work OK?


Follow-Up Postings:

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RE: Am I going to have a problem with voltage drop or heat?

THHW will be illegal unless it was also rated THWN or something else approved for wet locations, but most of the stuff out there these days is.

Your voltage drop estimations sound reasonable. Even at 60 it would be OK, you'll have less drop owing to the fact that your actual current flowing appears to be less than 30 most of the time (assuming your 120V loads are distributed across both legs).

The new building will need it's own grounding system (rods).


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RE: Am I going to have a problem with voltage drop or heat?

Sorry, the conductors are THWN wet rated, I typed it wrong.


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RE: Am I going to have a problem with voltage drop or heat?

Just a follow-up.

I checked amp's at the Sub-panel and with everything running and had right at 20amps per 120VAC leg. Checked voltage at AC recep. with AC off: 120VAC; with AC on and compressor running 118VAC.


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