Terminating the ends of electrical wire

Pulsedriver · 18 Dec 2015 at 17:44

Hey folks,

We have a couple of mains powered smoke alarms in the hallway, since the plasterers skimmed over the artex (and left them dangling) the screws and bracket no longer fit in place as they have plastered over quite a bit of the original area, so I would need to cut back around the plaster etc, try not to cut the artex under it etc etc so I am going to just take them down and replace them with decent branded co/smoke combined alarms, in their place.

The step I wanted to follow was this;

1) Turn off power at fusebox
2) Cut the 4 mains wires from each smoke alarm, take off connector.
3) Terminate the wire ends...
4) Push back into gap inside ceiling
5) Fit new ones in their place

The problem is, terminating the wires, if I use a wire block, it won't fit in the gap to be able to push back into the ceiling, so I was wondering if there is a better way? Perhaps to do each wire individually, but obviously in a safe way...Something that won't be so bulky and will fit to push up the gap.

Is there anything in particular available to buy for something like that?

Thanks

Entropy · 18 Dec 2015 at 17:58

I cannot understand how you cannot re-fit them? Drill a couple of new holes and screw them back up surely?

Pulsedriver · 18 Dec 2015 at 17:59

They look knackered out anyway, been there for a year years and are just basic ones, I can't get combined carbon monoxide/smoke alarms for mains power, well, not without spending a fair fortune.

JRJ · 18 Dec 2015 at 18:02

Are you talking about replacing the mains powered with battery?
If so has the house been built since 1992 if it has it must have a mains powered smoke alarm.

mattyfez · 18 Dec 2015 at 18:09

Electrical insulation tape? It's called that for a reason!

Entropy · 18 Dec 2015 at 18:10

The correct way is to remove the run of disused cable, which would mean getting a spark involved. Anything else is a bodge and cannot really be recommended. Likely cheaper and easier to just replace like for like detector.

Pulsedriver · 18 Dec 2015 at 18:10

1970's house so no requirement

Cutting a wire and taping around it? I did think of that but it reminded me of the old bodge job car speaker days of wrapping wires together and covering in electrical tape

mattyfez · 18 Dec 2015 at 18:13

It'll be fine if you tape the ends up good and proper.. And it's cheap so you don't need to be shy with how much you use.

R.C.Anderson · 18 Dec 2015 at 18:13

There's always the option of crimp caps? As long as they're atleast mains rated, and are crimped properly it shouldn't be a problem. Although as Entropy said, the only real way to do it is to remove the full run. Either way, remove the breaker for them in the fusebox rather than just leaving it off.

FloppyPoppy · 18 Dec 2015 at 18:16

The new T1000 crimpers are very versatile

darael · 18 Dec 2015 at 19:49

I'd wrap each wire a few times in electrical tape to prevent the possibilities of any shorts, then use more electrical tape to keep the insulated wires together.

Cyanide · 18 Dec 2015 at 21:46

Please don't use electrical tape. If you're disconnecting it you really should remove the cabling or at the very least find the other end and disconnect it so it's dead.

C.R.A.Z.Y · 18 Dec 2015 at 22:01

Cyanide said:
Please don't use electrical tape. If you're disconnecting it you really should remove the cabling or at the very least find the other end and disconnect it so it's dead.

+1
Isolate at the CCU and only re-connect/energize if/once the alarms are terminated correctly.
If however you don't plan on using mains powered alarms then make sure that the cables are cut back far enough at the CCU so that they cannot be re-terminated without extending the cables. (Cable at the alarms can then simply be cropped (stagger the phase, neutral and CPC so it's physically impossible for a short or arching (ALWAYS a belt and braces approach with electrics imho))

Lumeycom · 18 Dec 2015 at 22:06

C.R.A.Z.Y said:
+1
Isolate at the CCU and only re-connect/energize if/once the alarms are terminated correctly.
If however you don't plan on using mains powered alarms then make sure that the cables are cut back far enough at the CCU so that they cannot be re-terminated without extending the cables. (Cable at the alarms can then simply be cropped (stagger the phase, neutral and CPC so it's physically impossible for a short or arching (ALWAYS a belt and braces approach with electrics imho))

This.

Insulation tape is a joke and really shouldn't be called such.

Also, technically, any joint in any cable should be accessible.

Personally I'd refit like for like with something half decent like the round aico ones and lob a battery CO alarm up where needed

Lopéz · 21 Dec 2015 at 16:51

I'd terminate them by putting a Wago connector over the end and forgetting about it.

tom_e · 21 Dec 2015 at 16:54

Heat shrink a little longer than the wire then a dab of superglue to cap it off, bodge and a half but it's probably the sort of thing I'd do.

Hobbsie · 21 Dec 2015 at 20:24

so you are removing the wires completely? if so are they on their own fuse? if so disconnect from board.
scares me to think people will cut a cable put insulating tape over a live cable and leave it.

Pulsedriver · 22 Dec 2015 at 13:15

Local electrician came over to do it in the end (amidst other things) I didn't ask him how he did it, but hoping he's done a better job than I would have!