Move sensor. Extend cable

[TonyW2]

I intend to fit ceiling coving and need to lower a sensor from the corner angle. If I am lucky, there will be enough cable slack, but I am not optimistic
From searching this section of forum I think that the following method would enable me to undertake the job without setting off the alarm and without needing to reset it. Could somebody confirm, please, for reassurance as I do doubt my conclusion?

Accenta mini G3
Unknown engineers code.

Ensure alarm is not armed.
Do NOT turn off mains supply and do NOT open panel or remove battery.
Remove sensor from wall.
CUT the CABLE. or disconnect at sensor if accessible (This worries me. --Does not cutting the cable set off the tamper?)
Fit new cable length to sensor.
Solder and join cable, using heat shrink.(or use cable connector)
Alarm is "back to normal"
No need to reset panel

 

[rebuke]

Disclaimer - i'm not an alarm engineer, but I have installed a G4...

If the panel is set up such that it requires an engineer code to reset (it can be set up so that a user code will reset, I don't think there's any way of finding out without either requiring a reset or having the engineers code unfortunately), then I don't think you can move the sensor without a reset.

Basically, assuming the tamper wires have been connected, then even moving it you will trigger a tamper alarm, as you would have to take the lid off the sensor to get to the screws holding it to the wall, and it should have a microswitch inside that will break the tamper circuit. Note incidentally that a user code should always stop the tamper alarm, but it might not reset the alarm so it can be set again.

Cutting the cable is a bad idea, as you are likely to blow fuses in the panel (you will temporarily short out various wires). If I were doing it, and had either the engineer code or it was configured to allow a user reset, what I would do is:

Turn off the mains supply (for safety), and open the panel (this will trigger the tamper alarm, entering code should silence it)
Identify the cable that corresponds to that sensor, note down which colours go where, and then disconnect it in the panel (it should have two zone wires, two tamper wires (which will be part of the loop), and two power wires. Doing this might trigger a 2nd tamper alarm, but you can just silence that again.
Open up the sensor, note down which terminals each colour wire is in, and disconnect it.
Extend cable via whatever mechanism (solder+heatshrink / connector block etc)
Reconnect sensor
Reconnect wires at panel
Close panel
Turns mains on
Reset panel

If you don't have the engineer code (and can't get it), and it requires it to reset, then your only option I think is going to be to hard reset the panel, and reprogram from scratch...

 

[TonyW2]

Many thanks.
I guessed my "conclusion" was too good to be true.
Will do it properly and revert the panel to default, then reprogramme.

In mitigation, I quote from a post
"downpowering a panel is never a good idea and soldering a cable is not a reason to do it."

 

[rebuke]

Indeed that is true - my method didn't involve downpowering the panel (battery was always connected). The only reason I say to isolate the mains is for safety as with the panel open there are exposed connections to the mains wiring into the transformer...

 

[jkf1000]

You can temporararily disable the tamper circuit with a wire link in the panel, I would also disable the sensor from the panel if you are considering extending the cable to prevent a short in the 12 volt supply line,
You may be lucky and have enough cable spare as they are normaly wired from within the room and excess fed into the cavity, Karl

 

[plugwash]

but wont opening the panel to do that set off the tamper?

 

[breezer]

yes

 

[jkf1000]

it will set off the alarm, but all you have to do is put in your code and that will silence the alarm and just leave a flashing tamper warning on the panel, Karl

 

[TonyW2]

Thanks for the further suggestions, but I may as well revert it to default whilst I am messing about and get rid of the unknown engineer code for my future benefit.
(Full Installation manual is now available)
Thanks to all.

 

[Europlex]

If you look carefully at through the manual you will find a section that tells how to default just the Engineer & User Codes, leaving everything else alone.

Good luck and go slowly