DIY Doctor UK DIY Forums

Hello to all, I was called to help someone with their fire alarm that had been going all night. When I got there I found two alarm glasses broken and wires disconnected from the fused junction box feeding the alarm unit, turns out they had a bit of a party :roll: :shock:

I jammed the pins back up in the glasses so that I could silence the alarm. Checked the wiring with a non contact tester which proved there was a live feed but when I used a test lamp across L and N there was no light and same to earth. I noticed there was black around the live terminal as if they had touched to earth (maybe the party had a touch of the Major Tom about it :wink: ) anyway could someone enlighten me to the problem and a solution into the bargain. Oh and yes I did prove the test lamp.

Best regards.

The fire alarms I have worked on have resistors and are neither open or closed circuit but a resistance to the control panel that way the panel can detect tamper.
I will guess each make is different but this is really a specialist subject.
Eric

:D
Ye thanks Eric, solved the problem, just evicted the tenants and bingo :wink:

All back together and working, thanks again.
Not sure why but the live feed was showing as live with the non contact tester, could have been a number of factors. Traced through the spaghetti to the fuse which had blown. Replaced, connected, switched on the fuse box and viola mains power restored.

Best regards.

Thank you for reminding me a fuse when it blows can often allow enough current to track and light a neon tester.