> OK, I'm not an expert at this, just a "regular guy". To me, 50 feet
> doesn't seem like a particularly long run. It couldn't hurt to check
> though, before you do the wiring.
There are two factors to consider when selecting wire size, both the current
the wire can carry without overheating, and how much voltage drop the device
will see due to resistance of the wire.
10 AWG copper is almost exactly .001 ohms/foot, so 100 feet (50 out and 50
back) is 0.1 ohms. At 18 amps, that is a 1.8 volt drop, which isn't likely
to be noticed as long as the lift is on it's own circuit.
With motors, you also need to look at the drop while starting, which as a
general rule of thumb draws twice the running current. Even 3.6 volts isn't
likely to be a problem, although if there were an incandescent light on the
circuit, you'd probably see it flicker when the motor starts. ISTR 1% is
about the threshold for noticeable flicker.
You may also need bigger wire if the wire is someplace hot to begin with,
but I assume you won't be stuffing it in a conduit with a bunch of other
wires, or running it through locations above 40C. (And will be using wire
rated for 90C.) And although the NEC wouldn't approve, this is also an
intermittent application, so there's even less worry about the wire getting
hot.
OTOH, it won't hurt anything but your pocketbook to use 8 AWG.
Randall
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