Found out the hard way about voltage drop on long runs | Electricians

Joel Jenkins · 2026-03-09T18:25:06.546721+00:00

I was wiring a shed about 150 feet from the main panel for a new workshop. The lights were dim and the saw kept bogging down. I checked my connections, everything was tight. Then I looked up voltage drop calculations in the code book. For a 20 amp circuit at that distance, my 12 gauge wire was losing over 5 volts. I had to pull 10 gauge to fix it. How do you guys handle long wire runs on outdoor jobs?

lane.oscar6mo ago

That voltage drop chart in the code book is a lifesaver.

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keithpalmer6mo ago

Oh come on, not this again. Voltage drop is just a theory for people who like to overcomplicate things. I've run 12 gauge to my own barn, must be 200 feet, and the lights work fine. My old table saw starts up without a fuss. @lane.oscar and his code book charts are for people who worry too much. If your tools are bogging down, maybe it's a bad tool, not the wire. Pulling 10 gauge for a shed is a waste of money and a lot of extra work for no real gain.

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murphy.lisa5mo ago

I used to skip the voltage drop math too, but my miter saw tripping on a long run changed my mind real quick.

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