Electrical Wiring in the Home/compresser


QUESTION: hi bob,
i asked Bob Mossman a question.

i plugged in a compressor in my out building. when i wired the building a year ago i used 14 AWG and the compressor is 85 to 90 feet from the fuse box.
with no draw on the line i measured 125V, that dropped to 95V when the compressor was turned on (the outdoor temp was 30).
i am still looking into a "buck transformer" but was wondering if a ran a new 10 AWG line the 90 feet would that solve the V drop i am having?


What is the amp rating of the compressor?  Most likely the thicker wire would help, but make sure everything is the correct size.

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QUESTION: the amp rating is 11.5. would the 10AWG cover me?

i had gotten the advice to buy a 240V compressor and make the line 240V.
if that would work with my 14 AWG then why wouldn't changing the line to 240V and using a step down tran's to 120V?

you should be proud of your selves to help people out this way.
you are a blessing.


Each wire has an ampacity based on the type of wire.  Usually the retailer has a chart, since it would take an electrical engineer to figure out the voltage drop.

The difference between the voltage is not made with a transformer, it is made by the wiring.  Two hot wires deliver 240 volts.  One hot wire and one neutral wire delivers 120 volts.

11 amps and 90 feet should not cause that type of voltage drop if nothing else is on the circuit.  Is the compressor made for 110 volts?  Perhaps there is something wrong with the compressor.  If the compressor is 240 volts, then you would need to change the wiring.
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Electrical Wiring in the Home

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Bob Sponaugle


Just about any home wiring question. (not appliance repair) I have done all kinds of home wiring for myself, including adding a new breaker box, etc. Please, questions from North America only. Please be specific with details.

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