Help needed with electrics (power failure on burglar alarm)

stewie_griffin

Hi all

I'm hoping there might be friendly electrician on here who might be able to help me diagnose an intermittent problem I've had for years. To cut a long story short my burglar alarm fairly regularly loses power (normally for only a few minutes but sometimes much (much) longer!).



It progressively got worse so near the end of last year I got someone out to check the alarm. He checked everything over and couldn't see any issues (although the power was on at the time) however he did replace the backup battery with a new, bigger one as the old one was dead (unsurprisingly). What we did establish at the time was that the alarm was wired in to the lighting circuit and connected to it in the bathroom ceiling. To give some context, I live in a two story house but the layout is upside down (i.e. bedroom and bathroom downstairs). The alarm housing is in the cupboard under the stairs and the bathroom is further down the hallway. Apparently there's nothing wrong in wiring the alarm to the lighting circuit.

I thought that potentially the moisture in the bathroom could be causing the issue as there was very little ventilation as the window didn't open. In the new year I got a brand new window fitted and everything with the alarm seemed to be fine however over the last week or so it's gone back to how it was and I just don't know what's causing the problem.

I've had enough of this now so ripped up half of my kitchen floor (above the bathroom) so that I could access the wiring. I'm not an expert when it comes to electrics etc. however I couldn't see any thing obviously wrong and there didn't appear to be any moisture.

The photos below show the setup from above and were taken when the alarm was displaying power fail. Is there anything wrong with the way it's wired and if so how should it be done (don't worry if it's not a dead straight forward fix then I'll get an electrician in).





I've tried to annotate them the best I can. The white cabled labelled 1 (red) goes to the alarm and the one labelled 2 (red) goes to the light switch (pulley) in the bathroom. The wires going in to the 8 way connector are as follows:
1. Nothing
2. Live (red) wire from lighting circuit (1)
3. Neutral (black) wire from lighting circuit (1) and neutral (blue) from alarm
4. Neutral (blue) wire from light switch and live(brown) from alarm
5. Nothing
6. Live(brown) from light switch
7. Neutral (black) wires from lighting circuit (2&3)
8. Live (red) wires from lighting circuit (2&3)

The lights in the bathroom all work fine when there's no power going to the alarm. Please let me know if you need any further info. Thanks.

stewie_griffin

Hmm the photos don't seem to be working. Can anyone recommend a good image hosting website?

EDIT: If you right click and choose opening image in new tab then you can view them (Chrome).

Rubidium

I think that you have wasted time and effort removing the kitchen floor to get to the mains feed for the alarm.

The obvious thing would be to remove the alarm panel cover and check for the presence of mains voltage with a test meter, when the panel displays "Mains Flt".

When displaying "Mains Flt" it is working from the internal battery backup. It would display this if the mains supply was removed or during a power cut but I suspect that the real problem is in the alarm panel mains power supply unit, which produces the low voltage DC required for normal operation.

Often electrolytic capacitors used in these power supplies slowly dry out and eventually fail, therfore the fault indication is more likely not an actual mains voltage supply fault but an internal mains power supply unit fault.

Most electricians would not even attempt to locate and rectify an internal panel fault, so you may need a new alarm panel.

This image is hosted on tinypic.com

stewie_griffin

I needed to replace a few tiles in the kitchen anyway as they'd been chipped/cracked over time so it wasn't too much extra work.

What sort of test meter would I need and how do I go about testing the voltage? It's difficult to get anyone out to do it since we never know when the fault will happen and how long it will last for.

The alarm was fitted shortly before I bought the house so is only about 7 years old. Is it worth me posting a photo of the alarm with the cover off.

It just seems really strange to me that the fault only seems to occur 95% of the time shortly after using the shower.

There was a period in the past when it stopped working for a long time so much so I thought the alarm had given up the ghost but it randomly started working again. As I say it's only recently started playing up again so went several weeks without displaying the fault message after we started ventilating the bathroom better.

Does the wiring look correct as I want to 100% rule this out and I can then put my floor tiles back down.

MisterP123

Block 4 / 8 is Live
Block 3 / 7 is Neutral
Block 2 / 6 is your switched Live

Wiring looks correct.... Rough as a badger's !!!! and doesn't comply with regulations, but correct.

All junction boxes (or in your case some choc blocks.) need to be accessible, now this is open to discussion as you have proven it is accessible. But is removing flooring and floorboards really accessible? Carpet, maybe, yes. Laminate, nope.

Personally I'd replace it with an Ashley maintenance free junction box (actually I'd probably install new legs if it was feasible and ensure all connections are accessible.)

And Rubidium seems to be talking sense, fault probably lies in the panel.

stewie_griffin

MisterP123 wrote: »

Block 4 / 8 is Live
Block 3 / 7 is Neutral
Block 2 / 6 is your switched Live

Wiring looks correct.... Rough as a badger's !!!! and doesn't comply with regulations, but correct.

All junction boxes (or in your case some choc blocks.) need to be accessible, now this is open to discussion as you have proven it is accessible. But is removing flooring and floorboards really accessible? Carpet, maybe, yes. Laminate, nope.

Personally I'd replace it with an Ashley maintenance free junction box (actually I'd probably install new legs if it was feasible and ensure all connections are accessible.)

And Rubidium seems to be talking sense, fault probably lies in the panel.

Thanks MisterP123. I agree with you regarding the state of the wiring. A lot of my home still has the original 70's wiring (obviously the part in my photo has been modified recently - but not very well!) so I'd guess most of it isn't up to modern spec. Ideally I'd like a full re-wire but it's not something I can afford at the moment.I'd say it's definitely not accessible as the only reason I can get to it now is because I'm replacing some of my floor tiles in my kitchen and thought it was a good opportunity to look at the electrics.

I might see if a local sparky can come and tidy it up for me and fit a new junction box. What does install new legs mean? Would something like this do the job? http://www.sparkydirect.co.uk/product/39/18057/J803/Ashley-32-Amp-3-Terminal-Maintenance-Free-Junction-Box/index.html

I think I might replace the FCU above the alarm with one with a neon indicator such as this one http://www.sparkydirect.co.uk/product/2638/20146/CMA653/Click-Mode-13-Amp-Unswitched-Fused-Spur-Connection-Unit-cw-Neon-Indicator-/index.html as this should then give me a pretty comprehensive answer as to whether the issue lies with the alarm or the wiring. If the green led on the alarm is off but there's still power going to the FCU as per the red led then the problem would be with the alarm but if both lights are off then it would be the wiring.

I think my ideal solution would be to connect the alarm somewhere else so as to make that connection in the photo for the bathroom lights witch only but I don't know how difficult/costly that would be.

MisterP123

That jb would be a better solution than what you currently have.

By legs, I mean legs in the circuit, so basically replace the cable from the last light fitting to the bathroom light. The switch cable from bathroom light to switch. And then bathroom light to next light. Then choose a better place to spur off for the alarm.

Completely eradicating the need for inaccessible joints.

stewie_griffin

I have a bit of an update and a new plan...

I fitted a new FCU last Sunday and then didn't have any issues at all for a few days, so much so I actually thought the FCU may have been faulty and I'd fixed it. This optimism didn't last long as I awoke on Thursday to the dreaded mains FLT message! The power wasn't off at the time so I knew nothing new. However this morning the power was off to the alarm when I got up and interestingly the indicator on the FCU was also off. To me this means the problem isn't with the alarm but the wiring.

Anyway I've had a thought on how to fix it but I don't know if it will work. In the room next door to the alarm (it's more of a large cupboard) there's a plug socket that's never used. Could I replace this with the FCU I fitted above the alarm (with 3 amp fuse) and then wire this directly to the alarm? It would just need a hole drilling through the wall and then some cheap trunking fitted to hide the cable. Also if this is feasible then I assume 1mm 3 core cable would be fine due to the low load. My only concern is replacing a 13 amp socket with a 3 amp FCU (I could obviously replace it with a 13 amp FCU but this wouldn't be suitable for the alarm).

Any advice appreciated.

MisterP123

Spurs are fused at whatever size fuse you put in. You don't buy 3 amp versions and 13 amp versions.

Yes, you can do what you intend, you could just stick a plug on it and plug it in if you wanted! :rotfl:

stewie_griffin

MisterP123 wrote: »

Spurs are fused at whatever size fuse you put in. You don't buy 3 amp versions and 13 amp versions.

Yes, you can do what you intend, you could just stick a plug on it and plug it in if you wanted! :rotfl:

I was tempted to do just that but I thought it would look much better to hard wire it in etc. I've done a temporary job of just replacing the socket with the FCU and connecting it to the alarm as I don't have any trunking at the moment.