Guest roonster Posted August 13, 2005 Posted August 13, 2005 Hello, We ran some alarm cables around the house, but two of them we forgot to lable! One was the RKP and the other was a door contact. We tested it with an AA batery connected to two wires at one end (red and black in our case) The other end got a multimeter set it to Dc mode. Set meter to 20m dial. Not sure what thats means but we got a reading so gave us the results. Anyways then connected up the other end to the probes. if it gave a reading it was that cable. and then we labelled it relevantly. Anyways this was kinda a fidly way as we used an AA battery and insulation tape to tape the wires at one end. So what do the pro;s use? have you got special kit? Or do you tape wires to a battery as well?
Rich Posted August 13, 2005 Posted August 13, 2005 Well, personally I would twist 2 wires together at one end of one cable and measure the resistance at the end where all the cables run back to. Resistance would be marked on your meter possibly as ohm, continuity, resistance or a ohm symbol (broken circle shape). Whats happening here is the meter sends out its own voltage down the red cable, and if it comes back to the black the same as it left the red then there is a piece of electronic conductive material in between the 2 leads. If you have your meter set to resistance 2 or 20ohm and get a figure of 0 or 1 then basically your reading a piece of metal (wire) with hardly any resistive properties. If the meter did not display a number then there is no connection between the probes via what you are putting it across. I would reccomend you search the internet for some instructions on how to use a digital volt meter too. What is voltage, what is current and what is resistance before poking about any more with your meter
dpaengineer Posted August 13, 2005 Posted August 13, 2005 lol, if its just to identify a cable. Simply twist 2 of the cores together then use your multimeter to test continuity of the same 2 cores at the other end. Once u find the continuous pair. Untwist the them at twisted end and re-test for continuity. The second part makes sure u actually have the right cable and not just a staple through cable shorting it out. Trade Member
Guest PhAlarms Posted August 13, 2005 Posted August 13, 2005 as rich and use the Continuity test on the meters
Guest roonster Posted August 13, 2005 Posted August 13, 2005 ohh i knew there must have been an easier way! How do i set my mm to test to continuity? Ive lost the booket that came with it. I only figured out how to use it recently. Yesterday I was messing around trying to learn with a 12v car jump starter. Was messing around with the settings, when all oh a sudden there was a bang/sparks lots of smoke and the mm wires started melting! Its still working though then i decided its best to start smaller and got out the aa battery from the remote control...
Guest roonster Posted August 13, 2005 Posted August 13, 2005 Well, personally I would twist 2 wires together at one end of one cable and measure the resistance at the end where all the cables run back to.Resistance would be marked on your meter possibly as ohm, continuity, resistance or a ohm symbol (broken circle shape). Whats happening here is the meter sends out its own voltage down the red cable, and if it comes back to the black the same as it left the red then there is a piece of electronic conductive material in between the 2 leads. If you have your meter set to resistance 2 or 20ohm and get a figure of 0 or 1 then basically your reading a piece of metal (wire) with hardly any resistive properties. If the meter did not display a number then there is no connection between the probes via what you are putting it across. I would reccomend you search the internet for some instructions on how to use a digital volt meter too. What is voltage, what is current and what is resistance before poking about any more with your meter 64394[/snapback] ohh yeh. thanks to all who replied. Found it! hehe, learn something new everyday. I had to change the red cabled probe to V(ohm sign)mA to get the reading. Comes back as 0.05 when set to 200 on short piece of wire. (200 what may i ask?) edit, oh i see something! its got a red area marked around it which says ohms. So its 200 ohms i guess... ok gonna do a bit of searching now.. final edit: good site here on mm's http://www.multimeterwarehouse.com/usingamultimeter.htm
breff Posted August 13, 2005 Posted August 13, 2005 I use a tone generator and probe, connect the generator at the remote end go to the panel cables and find which one makes a noise, however if you havent got one then the multimeter with twisted pair at one end is your best bet. The opinions I express are mine and are usually correct! (Except when I'm wrong)(which I'm not)
whistle Posted August 13, 2005 Posted August 13, 2005 strip all cores back and test if all short you are on the correct cable or wire all the detectors and meter out latter, put power on pirs with battery and walk round and if it lights up your on the right cable.
Guest G.J.M Posted August 13, 2005 Posted August 13, 2005 most decent meters have what's called a diode selection mode but also doubles up as continuity. As mentioned before twist a pair of conductors together and if you get the right cable it will bleep,or if it does not have a bleep it should give a reading of 0 ohms. The diode symbol is this
Garry Posted August 13, 2005 Posted August 13, 2005 Why dont you just connect your battery and stick your tounge on the red and black... Sorted!!! Garry. You can lead a horse to water but you carnt climb a ladder with a bell in both hands.
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