rich wrote:
My homebuilt's master contactor is going bad. Sometimes when I turn it
on it doesn't make connection. It's got 1700 hours on it, so I'd just
as soon replace it. But the way the builder wired it, he's has
positive power from the battery going through the master switch to the
small terminal on the contactor. (cole-Hersey type) But the master
contactors, such as Spruce sells, are set up to actuate with ground
power going to the small terminal. They also have plastic around their
mounting feet so their case doesn't make ground. A starter contactor
would work perfectly with the way the plane is wired. I just wonder,
are starter contactors made to withstand continous use, like a master
contactor does? And how can one tell the difference in the two, they
look identical? And if not, can the master/continuous duty type be
made to work with postitive power to the small terminal?

A thought. Your master switch has hot on one side, and a lead to the
master contactor on the other.
If you replaced the existing contactor with a Spruce type contactor,
you would pull off the hot lead to the switch, and ground it.

Doesn't sound too hard, unless you have other wires tagging on with the
hot lead to the master switch.

Brian W.