By Mike Sokol
Last month I published an article about tracing short circuits in DC wiring without blowing a bunch of fuses. That turned out to be a very popular topic for my RV technician classes, so I’ve posted a 12-minute video here showing how it works.
If you have a short circuit in a wire, it’s going to blow the fuse every time you turn on the power. That’s because the short circuit allows lots of current to flow, up to 100 amps in a wire designed for maybe 15 amperes. The fuse is protecting the wire from melting, which is why you don’t put in a larger fuse. But how do you find where the problem is if you can’t turn on the power?
What shall we do???
Enter my simple fault-current tester that uses a blown fuse with an incandescent bulb soldered across it. In this graphic I’m using a 12-volt tester, but in the video below you’ll see me use a bulb soldered to a blown fuse to limit the fault current.
However, the really cool trick is to use a DC clamp meter to trace the current in the wires until it stops. And wherever it stops is right where the short circuit has occurred.
Read it, watch it, do it…
So if you’re looking for a short circuit, first read my article from last month on this topic, then watch the video below. In 12 minutes you’ll learn exactly how to perform this neat trick that can save you hours of troubleshooting time.
Click on the screen shot below to watch the 12-minute video.
Let’s play safe out there….
Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.
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