Can you tell me what size wire I need, or how many amps the solenoid for a
Mazda starter draws?



Sandy McNabb

Renesis in a Glass Goose

As near as I can tell the the resistance of the solonoid is
about .8 ohm.

So the current will be about 15 AMPs. At 12 volts. V/R = A
http://www.powerstream.com/Wire_Size.htm

Lookslike about 10 gage stranded wire.

Paul Lamar


10 gauge is way overkill for a solenoid, which is intermittently
used.The chart is for NEC code, which is continuous loading,
which relies on max bundle size for wiring. Hence 14 gauge
for 15 amp breakers (lighting loads) and 12 gauge for wall
sockets (20 Amp breakers).

14 gauge would be sufficient for solenoid use.I would be
surprised if Mazda used anything larger.

Bob Knuckles, Aeroelectric, puts out a pretty good book
on aircraft wiring that I would recommend.

Tom W

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Tom W,

I learned how to use my multi-meter to measure amps. The starter
solenoid draws 8.14 amps so I'm considering an 18 AWG wire with a
10 amp fuse....or should I go higher?

Sandy McNabb
Renesis in a Glass Goose

Sandy, what are you gaining by using smaller wire?

What you lose is a tiny bit of power to the solenoid.

Starters are around 3 HP so 190 amps so the solenoid
current is minuscule by comparison.

Paul Lamar

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Paul,

I'm not an electo-geek....just trying to get the right sized wire and fuse
for the situation. 18 AWG is advertised to take care of 10 amps and the
solenoid draws 8.14 intermittently, so that's where I started. I know that
some guys use a contactor to activated the solenoid, but I wanted to reduce
the parts count and failure points. Since the Glass Goose is a pusher, I
didn't
want to run a big wire 8' to 10" to the solenoid. So, I just looking for the

right wire to do the job.

Thanks,

Sandy McNabb

12 gage is not big sandy. Very little weight. I would err on
the larger size. The fuse has nothing to do with the wire size.

I can see no down side to larger wire but I can see a down
side to wire that is too small. The Megasquirt guys recommend
nothing smaller than 16 gage.

Paul Lamar