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Anybody Know Anything About House Alarm Wiring


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Hopefully simple one if you do, having double glazing fitted and found a suprise magnetic contact buried in the side of the door.

Don't think any of the wires are cut or broken so I dug the magnet part ( well the magnet only !! with no plastic support ) from within the door and have tried matching it to the other side with the wires but can't get it not to trigger an alarm on that circuit. I've tried twisting the magnet through angles to ty and match the poles but no success.

So question is - there are two sets of wires going to this contact, both with I think four wires in each. Can I just undo the wires and join like coloured wies to get it working again without this one .... or is it more complicated than that. As it's a utility I don't really need this part of the alarm working as there is sufficient elsewhere to cover.

Anybody help please?

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There are usually 4 wires from the device to the board, 2 are permanently connected in the unit and 2 which are switched. The 2 that are permamently connected it provides a loop back to the board as an anti tamper alarm, if they go open circuit it will alarm as it thinks the cable has been cut. Sounds like that's what you got.

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If there is a separate window that opens it is likely that the second cable goes to that contact through the frame.

When you say wire colours do you mean from the switch or the cable to the board. I have had door contacts with all wires moulded in and coloured white, the only way you can tell is by using a continuity tester or a multimeter. You could try shorting all the wires back to the board and see if that clears it, but some systems actually have a resistor across the tamper so that a short shows as a tamper alarm as well as open circuit.

The actual wire colours used in the cable to the board would be down to the installer, waht have you got and I could stab a guess possibly.

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It could of course be that 4 core cable was used for this contact switch, which in actual fact may require just 2 wires. 4 core ( or more) is common in alarm systems and generally is such that 2 wires ( usually red and black/blue) carry 12v supply for passive infra red ( PIR) detectors (which are common throughout the building)-the other 2 wires are switch wires ( usually activating the panel when open circuit) so .....if there is a red and black use a meter to detect 12v. If so, tape 'em up (seperately)and join the other 2 wires together. Set alarm, and pull apart the 2 wires, - see if alarm acivates :)

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It could of course be that 4 core cable was used for this contact switch, which in actual fact may require just 2 wires. 4 core ( or more) is common in alarm systems and generally is such that 2 wires ( usually red and black/blue) carry 12v supply for passive infra red ( PIR) detectors (which are common throughout the building)-the other 2 wires are switch wires ( usually activating the panel when open circuit) so .....if there is a red and black use a meter to detect 12v. If so, tape 'em up (seperately)and join the other 2 wires together. Set alarm, and pull apart the 2 wires, - see if alarm acivates :)

Would agree except that the switch sounds like it is wired as a radial hence little chance of PIR power on the cable. Also activation of the reed switch with the magnet still gives an alarm condition, hence the assumption that there is a tamper circuit.

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It looks like this:

http://www.connectstores.com/topsecurity/i...reed_switch.PNG

At least what's left of it.

There are two cables coming into it, both have four wires inside. I think they are red, black, blue and yellow - but they are all taped over at the moment. I'll check in a bit. Each pair of like colour wires join to a terminal on the switch.

I did get it to work a couple of times by taping the magnet to the reed switch but as soon as I tucked it away into the brick work it faulted that circuit again, could this be gravity?

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It looks like this:

http://www.connectstores.com/topsecurity/i...reed_switch.PNG

At least what's left of it.

There are two cables coming into it, both have four wires inside. I think they are red, black, blue and yellow - but they are all taped over at the moment. I'll check in a bit. Each pair of like colour wires join to a terminal on the switch.

I did get it to work a couple of times by taping the magnet to the reed switch but as soon as I tucked it away into the brick work it faulted that circuit again, could this be gravity?

You could always just replace the switch, they're only a couple of quid for the set.

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It looks like this:

http://www.connectstores.com/topsecurity/i...reed_switch.PNG

At least what's left of it.

There are two cables coming into it, both have four wires inside. I think they are red, black, blue and yellow - but they are all taped over at the moment. I'll check in a bit. Each pair of like colour wires join to a terminal on the switch.

I did get it to work a couple of times by taping the magnet to the reed switch but as soon as I tucked it away into the brick work it faulted that circuit again, could this be gravity?

check for 12 v on redand black as Isuggested.if so ...follow post :D ( yes - replace the reed and magnet assembly ( maplins or the like )

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Other possible is a broken wire that opens when you put the reed switch back in place. I would replace the switch assembly anyway.

Check for volts on the Red/Black but there is no reason for there to be voltage on them in the first place not unless the system is zoned and has PIR detectors as well as the door/window contacts. For this to work the devices would need to be wired in series to from a loop to work, in which case you need to make sure that you don't activate the PIR/s at the same time as you are taking the short off the switch wires. Also if they were wired in series you would have 2 cables into the switch one from the panel and one to the next switch which you don't have, or they are series wired inside the panel, in which case there would be no need for DC power to the switch. In fact I woiuld go as far as to say that it would be bad installation practice to put power on an unused pair, if they were shorted either accidently or delibarately it would take out the fuse, or worse.

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So if I have four wired on there ( pairs ) if I get a new switch ( got to use a surface mount as rgs. say you can't drill double glazing door frames :( will it set the tamper if I undo the wires? If so will normal code reset it?

I think a trip to either B&Q or my local alarm shop is needed tomorrow.

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Sorry didn't really read your last post, you have got 2 cables going into the switch. Eunos800 is most likely correct and 2 wires may well have power on, probably red/black. Apologies due there.

A like for like replacement of the magnet and switch will probably sort you out just be careful that you don't mix up the terminals. There should be a normally open (N/O), normally closed (N/C) and common for the switch and the other are just screw terminals for jointing wires through. The N/O will be open with no magnet and the other way round for the N/C, they will probably be the yellow and blue wires. The switch is probably wired on the N/C contacts. You could just try replacing the magnet part, that may work.

Also you say about "tucking the switch away in the brickwork", how far away is the magnet from the switch? It has to be fairly near to work properly

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Thanks fot advice Mac / Eunos.

OK, i't moved on a bit. The new door is fitted so the wires and remains of switch are poking out the top of the plaster in the corner. I can't fit same type of switch as I am not allowed to drill into door or frame so I need to either get a surface mount one ( I'll try this morning ) with the same number of terminals or alternatively try and wire it all up so that it's not in use and doesn't trigger the circuits.

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OK, I've sussed out where the wires are going - just need some advice on how to connect to new surface mount and if the tamper will sound when I pull the wires apart.

First up - the two outer cables. One is coming in and the other goes onto another flush mount on another door.

Second up - the colours are red, black, blue and yellow.

Third up - the blacks join together on a terminal, as do the blue, as do the yellow. The two red wires go to different terminals. So would I be right to assume that these are the ones that are switching with the reed. Or is my simple electrics knowledge getting mixed up?

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I had a quick look at the specs for the switch that you have and there are only 2 contacts for reed not 3 as I posted last night. The remaining 3 terminals are for tamper. As the contacts are closed by the magnet the switches must be wired in series to work. It would make sense that the reds form a loop through all the switches. You can test by disconnecting the reds and shorting out, set the alarm and take the short off and the alarm should go off.

For connection of the new switch I would use one of THESE fixed to the wall where you can get the existing wires into it. Use a short length of 2 core cable to extend the reds out to the new switch. The remaining three terminals can be used to joint up the other cores in the 2 existing cables. If you wanted to get fancy you could include the tamper switch in the terminal box in the tamper circuit :D

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Cheers Mac. I think the first thing I will try is to disconnect the two reds and join them. Then see if the alarm sets. If it does then I'll do as you suggest and break the connection and frighten the guys doing the double glazing ( make sure they haven't got a glass panel inbt heir hands first !! ) :)

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Well I joined the reds today and the alarm is now setting OK. So tomorrow I am going to disconnect the rest ( in pairs ), make sure they are well joined and put the pairs in shrink wrap. Then I'll hide them all. I couldn't put a new surface mount contact due to the shape ( contours ) of the door. The two parts would be too far apart :(

Can you safely solder wires if there is 12 volts running through them?

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Well I joined the reds today and the alarm is now setting OK. So tomorrow I am going to disconnect the rest ( in pairs ), make sure they are well joined and put the pairs in shrink wrap. Then I'll hide them all. I couldn't put a new surface mount contact due to the shape ( contours ) of the door. The two parts would be too far apart :(

Can you safely solder wires if there is 12 volts running through them?

Yes - provided you ensure that the iron tip itself does not short out the Voltage across other wires as you are working. The 12v alone is harmless to us humans:-)

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