Re: Cigarette Lighter outlet

["Loyd Heimbruch" <Loyd.Heimbruch@domain.elided>]

Glenn posted:

"plugging into the Spider resulted in the pump running for about 3 seconds
and then blowing the 10A fuse.=20

"I understand there may be some bad grounds on the car, I guess I have =
some
connections to clean - but I just wanted to make sure first - Should the
Spider be able to handle the load? There's no label on the pump saying =
what
the draw is, but it can't be that much. Not ridiculous, like a hair dryer =
or
something..."

The electrical system in your Alfa is a 12 volt system.  The 10 amp fuse =
is intended to protect the wiring connected to it, which is probably sized =
to handle a 10 amp load without overheating and melting, causing a fire.  =
At 12 volts, the circuit will be able to safely provide power to a device =
rated at 12 watts.  There should have been a label on the portable pump =
indicating amps or watts.  If not, check the literature that came with the =
pump, or contact the manufacturer.  If the load is over 12 watts or 10 =
amps, the fuse did what it's supposed to do (which I expect is the case).

A bad ground would not cause the fuse to melt, it would simply result in =
the device not operating.

A ground fault (or short circuit) would cause the fuse to melt regardless =
of whether any device is connected to it or not.

It is possible that a poor wiring connection at the load side of the fuse =
box can cause resistance and generate heat, which may be transmitted to =
the fuse and cause it to melt.  This is not likely to occur in the 3 =
second time period that you describe.

The electrical system on your Contour may have had a larger size wire and =
larger fuse to provide power to the cigarette lighter.

Loyd Heimbruch
Barnum, MN
1978 Niki Lauda Spider

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End of alfa-digest V7 #1358
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