test wiring for break or short


Old 09-15-04, 04:42 AM
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test wiring for break or short

I have a very old wired alarm system with at least two breaks or shorts. It only has old keypads and I want to replace system with a new control panel (hybrid type) and some new wireless sensors. But first I want to locate the breaks and fix the old wiring. I tried using a phone testing device (the one where you clip a sound-generating device on one wire and use a pointer to locate the break). Unfortunately, it does not work -- the sound is so loud, it jumps to the next wire in the pair so I can't trace the break. A guy at radio shack said that an ohm reader would work, but he did not know how to use it. Any suggestions? The telephone device has two clips -- I was thinking of putting one on one wire and the other clip on the second? Or would this ohm thing be better? If so, how would I use it?
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Old 09-15-04, 04:17 PM
Join Date: Jul 2004
Location: Dallas area
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I use both of these tools. The Ohm meter will tell you if you have a short or open on the wires. You would take the 2 leads of the meter and put it across the 2 wires. With the meter set to ohm you can get a reading some meters actually emit sound on a short. For a base reading just short the meter leads together without a wire this is your shorted reading most windows that open and close will have a short when closed and an open when open of course.

The sound generator with the wand works well with finding which wire is which in the field. So if you have found a wire that you suspect has a break...cause you read an open loop. Put the toner on the 2 wires. You will get tone and when you short the wires the tone drops out. This is how you ID the wire. So if you are in the attic and you have tone being sent from the panel and have a good idea where these wires go ie. windows/doors what have you. You can now head to where you believe your break may be. Once the wire is found short it out and listen for the tone to stop.

A typical troubleshooting tip is that most often the break is at the window in a contact or bad splice, but if you have animal evidence in the attic it could be there. First thing I do is ID where the wire goes, which window or door. Then I pull up the contact and expose the wire. From here I can put tone on it at the window and go into the attic and make my own cut and find out if its ok going down the wall to the window. If thats good then I check from my new cut to the panel. If its bad to to panel I tug on the wire look for attic cuts or chews and if nothing is found I rerun the wire or find and fix whatever problem I can find.

My 2 cents

Let us know how it all goes or if you have any other questions.
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