Using a compass to find a short?
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Mountain Pass
Joined: Oct 2011
Posts: 208
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From: Cheyoming
Using a compass to find a short?
The mechanics at work said that a regular old Boy Scout type compass will help locate a short in wiring. Any confirmation of this? Or are they just getting a chuckle?
Says it spins at or near the short because of the field created by current going to ground.
Says it spins at or near the short because of the field created by current going to ground.
Moderator
Joined: Jan 2001
Posts: 56,984
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From: Virginia
I can't say whether it would indicate anything or not, but I do know most wires in a automotive application are bundled together, and I would think it would not indicate anything with a bunch of other circuits bundled next to it. If you have to go over the harness close enough or tear it apart enough for this idea to work, you would find the problem visually long before you got to use your "indicator". I think they are pulling your leg.
Hotshot
Joined: Jan 2004
Posts: 19,762
Likes: 1,079
From: St Louis
A compass, by itself, will not work. You need to also inject an AC signal into the shorted circuit.
It's a heck of a lot easier to just buy a short circuit detector and use it.
It's a heck of a lot easier to just buy a short circuit detector and use it.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
As all have said, you cannot use a compass to find a short in a wiring harness. Even if the needle did move because of the field created by excess current to ground, I don't understand how you would correlate needle alignment to the physical location of the current flow in a bundled harness. And even then, current flows through the entire length of the wire between the source and the short to ground, not just at the physical fault.
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