Alarm cabling major error !

[Sc0tty]

Hello everyone, this is my first post so please go easy !!

I had to cut some low voltage alarms cables in my loft today to reroute them and extend them due to a loft conversion. I made the fatal mistake of cutting the cables that go off to various circuits before I labelled them (DOH !!!!!!!) I now have 4 cables that disappear off to various circuits (PIR, door entry/exit contact, external siren, and internal siren etc?) and 4 cables that go back to the control box where the battery and circuit boards are housed.

Does it matter if I reconnect the 4 cables from the control box to the wrong cables that dissappear off to the 4 circuits/zones? Will this clear down the fault codes on my system panel even if I cross wire?#

The other thing that happened when I cut the cables was the external siren went off, and this seems to be direct live so the only way I could silence it was to get up the ladder and dissconnect the red cables from the block that feed the 2 sirens.

ps I am using 8 core colour coded alarm cable to extend the wiring in the loft.

HELP !!!

 

[ekmdgrf]

Cutting cables always a bad idea. Not least because there isn't a nice way to put them back together again but also for the reason that you've discovered. It's going to be hard to identify the cables. If there's some play in them, you could try getting someone to pull on one end and see what moves at the othe end. Failing that, I'd get a tone & amp on it (http://www.extech.com/instruments/product.asp?catid=2&prodid=9 (first result on a well-known Internet search engine)). You'll have to disconnect the cable from the panel, so make a note of which core connects to which terminal. I'll say that again. Make a note of which core goes to which terminal and for good meausre, take photos, so that if all else fails you can refer back to them but get a pen and paper and take notes too!

 

[Sc0tty]

Many thanks for the reply. I am unable to identify which zone connects to which cable because of the location of where the cables come into the loft space.

Could I not try and guess it by connecting cable #1 from the control box to one of the 4 cut ends, and by process of elimination connect the cables together until the zone fault alarm clears from the user panel?

Then continue with this method for the 2nd, 3rd and 4th cables until all are reconnected as per original?

(basically I have 4 cables cut coming from the control box and obviously another 4 cable ends cut going off to the PIRs etc..... So I have a one in four chance of connecting the first cable run back up correclty, followed by a one in three, etc....)

 

[ekmdgrf]

I'm not an alarm expert, I've just run a lot of cable

Off the top of my head, it really depends on the panel as how how it detects tampers and how they are cleared. Almost certainly you'll have to enter something on the panel to clear the tamper but also, if you connect things up randomly and again, it depends on the panel, I'm fairly sure you may be able to clear the tamper but have it wired up wrong.

What I would do is try to idenfity the correct cables. Another way to do it would be to disconnect the wires (making careful notes) and then short two cores together at one end. Then goto the other end and use a multimeter to test for continuity/resistance. You'll know when you have the right cable.

 

[DaftPunk]

Time to call an alarm person I'm afraid. You've already blown at least one fuse in the end station and randomly guessing what goes where just won't work. Also there's the issue of making a reliable joint on all those wires.

 

[biker1]

Certainly not an expert, but couldn't you test for continuity to find which is which?

 

[bernardgreen]

Identifying cables from the panel

In one cable short black to red. in the next short black to yellow etc etc

That saves a lot of trips up and down the loft ladder.

Working out which cable end in the loft goes to which sensor will need

[1] find which colours are the alarm pair at the sensor. These will ( should ) match the colours connected to the Zone inputs ( not tamper ) at the panel for that sensor.

[2] Then with someone walking across the sensor check the pairs in the loft to see which is changing.

 

[Sc0tty]

Time to mothball it then I think. It is an old system, and you can buy I wireless alarm systems these days.

We hardly ever use the alarm anyway and since we had our front door changed there is no longer an entry/exit magnetic contact. Shame beacuse the previous owner must have spent a fortune on it.

One more thing, the external sounder and stobe is wired directly to mains bypassing the consumer unit. Is there any way to make this constant live 'dead' or safe when I remove/replace the unit?

Again I cannot locate this mains wire as the house has converted since this damn alarm was installed over 15 years ago

 

[ekmdgrf]

How on earth is the bell wired into the mains? I can only think it must be wired into a henley block? If it really does bypass the CU, then if it should develop a fault the circuit protection device that will operate is the service fuse and that will be bad news. The only way to safely remove the cable would be to either get a spark to do it or call the DNO and request a temporary disconnection. Are you sure it's wired like that? Also, aren't bells generally 12V and fed off the panel?

 

[EightyTwo]

Before you do anything else...

Have you disconnected the mains supply and the backup battery in the panel? If not, it would be a good idea to do this! You have probably blown the fuse for the 12V supply to the PIRs and bell already but powering the whole thing down would be a very sensible precaution.

The bell. It will ring if you deprive it of power by cutting the cable or ripping it off the wall. Unless it is very old (20 years+), it will stop after about 20 minutes - just about enough time to get your ladder out... It has its own internal battery.

In my early days, I did this once but only with two cables. I was able to look at the ends and work out which was which - I had cut one cable straight across and the other at an angle. You might not be that lucky!

DO NOT TRY THE TRIAL AND ERROR METHOD! Wiring your bell to a PIR zone would not be a good idea!

Don't junk the alarm - a wired system is much more reliable (and secure) than a wireless one and you don't need to buy pounds of batteries every year. Fit a new door contact.

bernardgreen has told you a great way to work out which cable is which. Do you have, and can you use, a multimeter? If not, what other electrical test equipment do you have? This problem is not unsolvable but you will need to take a logical approach and use your test equipment. If you're not confident, get a man in or a mate that has a multimeter!

Once you know which colours are used for what, you could use the alarm battery to power up each PIR in turn. Go and see which one lights up... You can write on white alarm cable with a fine permanent marker pen or a CD/DVD marker. If the cable is brown, make some little flags by folding some white tape or masking tape around the cable. It's often easier to write on the tape first and then put it on the cable.

Posting good, clear, close-up photos will help us to help you.

 

[Sc0tty]

Guys, when I cut the cables in error the external bell/siren would not switch off even when I disconnected the battery from inside the ctrl panel and then I isolated the mains by switching off the double pole RCD and normal on/off MCBs on my C/U. The external sounder was still going off at that time! This is why I had to get up the ladder and diss the red wires from the connector block into the 2 sirens. (ie isolating the sirens from the mains.) I found all the paperwork, the system was installed in 1991 !! Even the handbook mentions the sounder should silence after 20 mins this did not happen. It also mentions the external strobe and sirens should be constant live.

Since living in the house since 2000, we had a garage conversion and a new C/U installed, and the electricity board moved the incoming mains cable to a new position and an electrician wired all the cables into a new MCB type C/U.

When we bought the house it had an old style fuseboard with an analogue meter etc mounted on some wooden board in the garage. When we had the garage conversion the electrician and I decided to have the meter and incoming mains supply cable moved (by SSE) to a meter cabinet on an external wall of the garage, so as to free up wall space in the garage room post conversion. This is what puzzles me as I would have expected the electrician to have located this rougue permanent live cable that feeds the strobe/siren box?!!

My concern now is how to isolate the live mains that feeds the extenal sirens as I wish to decommission the whole system. How on earth can their be a live feed that has no breaker? And more worrying, how can it be isolated/made safe without pulling the garage room CU off the wall and even removing some plaster board to locate this mains cable?

 

[ekmdgrf]

Ahh, that makes a lot more sense. The bell doesn't have a mains feed but it does have it's own battery, separate from the one in the panel. It's there so that if someone cuts the bell wire, the alarm still sounds.......as you found out!

 

[Sc0tty]

I will climb the ladder tomorrow guys and photograph the external bell box with the cover off. Hopefully the battery will be there for all to see. I sure do hope its not permanent live mains running to box.

 

[EightyTwo]

Ahh, that makes a lot more sense. The bell doesn't have a mains feed but it does have it's own battery, separate from the one in the panel. It's there so that if someone cuts the bell wire, the alarm still sounds.......as you found out!

Like I said...

Close up photos of the control panel connections would be useful. Then we can help you work out which cable end is which...