The unit should have a motor data nameplate, telling
you this. If not then:
Amps when HP is known:
(HP*746) / (E*%Eff.)
If you have no data, then IMO you need to get it to
make sure you have a safe system.
The following is based on the NEC. I don't know how
it compares to the automotive standards, but you
can't go wrong with it:
Assuming 1/10HP, 12V, and a typical 50% efficiency,
then amps = ~12.43.
Wire size needs to be rated at least 125% of this
value, or ~15.54A / 16ga wire (assuming 90degC
rated). Then it's derated based on a heat rise
factor. Assuming a location temp of 150degF, then
14ga wire rated at 25A (25*.65 = 16.25A) will be
required.
For fast acting fuses, a max of 400% of the FLA is
allowed (50A). For 'slow blow' 225% (35A).
So in this case neither type of 30A fuse is
sufficient.
If a switch is used, then it's rating should be 2x
the FLA, or 25A.
The Grainger catalog lists 10.5A for the little
Thomas 1/10HP unit. It's requirements are:
14ga wire
40A Fast fuse
20A Slow fuse
25A Switch
Check for voltage drop to the unit, since current
increases rapidly. Conversely, it drops with
increasing voltage. Supply wire should be connected
at the battery, with the fuse near the unit for best
protection.
GM
----- Original Message -----
> Does anyone know what the current draw of the
electric air pump should be? I have the one that
Terry sells.
>
> It blows 30 amp fuses pretty regularly. I am
thinking about switching to a larger fuse, but am not
sure if that would be safe. What size fuse do other
folks use with the electric pump?
>
> Scott Isensee
>
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