Ceiling Light Problem Works When Wires Are Wiggled


Postby sophie716 » Fri Oct 18, 2013 2:06 pm

Our house is less than 7 years old. A little used ceiling light in the lounge is not working. I have checked the wiring in the switch box and all looks OK. I have taken down the 5 branch light fitting and connected a a single bulb fitting to make it easier to manage. When I wiggle the wires from the ceiling there is an intermittent flash of light. I have connected this single light fitment with a temporary cable across to the light switch using the negative wire (blue) from the switch box and the live and earth from the ceiling. This works perfectly.

Please, does anyone have any ideas about what I should do next? I'm hoping it doesn't mean taking up bedroom carpet etc or cutting a bigger hole in the downstairs ceiling!!

Any suggestions would be very welcome.
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Postby ericmark » Fri Oct 18, 2013 4:47 pm

[quote] I have taken down the 5 branch light fitting and connected a a single bulb fitting to make it easier to manage.[/quote]
From that statement I would expect to find the original ceiling rose has been removed and replaced by some botched up connection which I would hope with power off at isolator you could draw out of the ceiling and remake in a proper fashion.

Borrowed neutrals are very dangerous as items which appear dead can become live as the neutral is disconnected since you admit you have done this I would turn the supply of using the main isolator not just the MCB as because of borrowed neutrals as you disconnect things they may become live.
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Postby sophie716 » Fri Oct 18, 2013 6:52 pm

Thank you Ericmark for your reply.

Yes the original ceiling rose was removed just after the house was built, and a light fitting was fitted with the usual bracket screwed to the ceiling. This has been in placed and used lightly, for the past 7 years.

Thank you for the information about borrowed neutrals being very dangerous. I thought this exercise would prove whether the neutral line was was ok or not. Would you say, that it proves nothing and the problem is somewhere else?

Thank you,
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Postby sophie716 » Fri Oct 18, 2013 9:37 pm

Thank you ericmark for your reply.

Yes the ceiling rose was removed 7 years ago when the house was built and the new light fitting was installed with the usual metal bracket screwed into the ceiling. It was neatly done and we haven't had any problems until now. However, the wires are quite short (presumably clipped to the beam above the ceiling) so can't pull them down very far.

Thanks for the information above borrowed neutrals being very dangerous.

Are you saying that with the light working with borrowed neutrals does not prove that our problem is with the neutral wire in the ceiling? If so, is there anything else you could suggest?

Many thanks.

Sorry if this is a repeat. I sent a reply but it is not showing.
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Postby ericmark » Sat Oct 19, 2013 10:41 pm

Often a bit of twin and earth is used as a clip to keep the wires tidy and common not to have much slack. I will admit my domestic is limited I was mainly industrial but I have talked to my son many times about access to cables I would look to removing floor boards but he will remove a lump of ceiling there is no right and wrong method it's down to personal preference as to how easy to reinstate.

Drawing a light pencil mark around the area covered with the rose or light I have normally been able to gain enough assess to at least remove the item clipping the cables but may be just lucky.

In the main one expects to see the same number of line cables as neutral other three of each plus two switched line that includes the lamp its self.

So ceiling rose will often be two switched line, three line, three neutral at end of run then two line and two neutral one neutral in count being the lamp its self.
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Postby sophie716 » Sun Oct 20, 2013 12:04 pm

Thank you Ericmark, for your further input. It's so good of you to take the trouble in responding.

My husband and I have talked for many hours about this problem and the best way to get it fixed. I must say, the thought of removing carpets and floor boards, horrifies me! Making a bigger hole in the ceiling sounds preferable. Maybe we are worrying for nothing and some bright 'spark' will find it's not a big job at all......I wish.

I guess the next job is finding a competent electrician. You hear so many horror stories on TV. Would you go to an electrical company or an individual?

Kind regards to you and your son,
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Postby ericmark » Mon Oct 21, 2013 12:21 pm

There are pros and cons to both. With sole trader who is a scheme member you know he has been tested by scheme provider but with large firms the electrician you get may have never been vetted by scheme provider it is firm as whole who is tested.

But clearly with sole trader some thing goes wrong even catches the flue and job delayed.

Personal recommendation is always best but to be frank I have watched some of the TV programs where they state "There is no way he should have done that" and I think to myself yes there is that complies with regulations clearly there are rouge electricians out there but not to the extent that the shows make out.

I would personally look for sole trader as he is likely to take the time required. From a firm he has a boss who will have given him a time slot and he will want to be in and out within that time but sole trader can spend the time he needs to correct. However really big firm may send electrician and plaster so it really is swings and roundabouts.

Tell them the problem and see what they say. And those who say not into plastering make a note of as clearly they will be good for other work as honest.

In real terms not a big job and likely best option is open yellow pages and stick in a pin.
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Postby sophie716 » Mon Oct 21, 2013 4:46 pm

Hi Ericmark,

What a great comprehensive reply. Yes we have considered the possibility of plastering, just in case!

Your comments have been really useful and I must thank you very much for your time.

Regards,

Beryl
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Postby sophie716 » Fri Nov 01, 2013 3:12 pm

Hi Ericmark,

After being so helpful, I thought you might be interested to hear the outcome of our ceiling light.

We had an electrician call last week to have a look at the problem. He had a scope light with a little screen which he put up through the ceiling hole but unfortunately couldn't see where the problem was. As he said, he could make the hole bigger but still may not be able to get to the problem and you would never get the ceiling repaired to look like new again. He said the best option was through the bedroom floor. We prepared ourselves for the big upheaval and he returned on Tuesday this week. He said he had been thinking about it over the weekend and he could wire it up using the earth wire in the switch which wasn't attached to anything. He assured us that it would be perfectly safe although not technically not correct. The light is very little used but at least it does work.

Once again, many thanks,
Beryl
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Postby ericmark » Fri Nov 01, 2013 9:23 pm

It sounds bad however until 1960 we had no earths to lights so although I personally would never use an earth wire for anything but earth I will admit it could be safe and since not on site I can't really criticise the work without seeing it.

Also with twin and earth the earth wire is not coloured green/yellow so not really a case of over sleeving so not sure if complies or not.

So I think you are lucky getting an electrician who thinks outside the box and nice to hear all now OK.
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Postby DIYorNot » Sun Nov 03, 2013 12:41 pm

If the cable is twin and earth, the earth/CPC conductor should not be used for anything other than earth. The earth conductor is unsleeved throughout its length of the cable. Also, the conductor cross sectional area is less than the live/phase and neutral conductors.
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Postby ericmark » Sun Nov 03, 2013 6:39 pm

[quote="DIYorNot"]If the cable is twin and earth, the earth/CPC conductor should not be used for anything other than earth. The earth conductor is unsleeved throughout its length of the cable. Also, the conductor cross sectional area is less than the live/phase and neutral conductors.[/quote]
I was temped to say the same but could not find a regulation to support this. 514.4.2 stops over sleeving green-and-yellow.

[quote]514.4.6 Bare conductors
A bare conductor shall be identified. where necessary. by the application of tape, sleeve or disc of the appropriate colour prescribed in Table 51 or by painting with such a colour.[/quote]

So I can't find a regulation to stop using a bare conductor suitable sleeved for line. The only regulation I can find is Table 52.3 - Minimum cross-sectional area of conductors where it states that bare conductors shall be at least 10mm however I don't really know if a conductor within the grey insulation is really classified as bare.

Although I would never use the earth of a twin and earth cable for anything but earth to say another who has is breaking the rules is much harder.

[quote]134.1.1 Good workmanship by competent persons or persons under their supervision and proper materials shall be used in the erection of the electrical installation. Electrical equipment shall be installed in accordance with the instructions provided by the manufacturer of the equipment.[/quote]

Since the manufacturer states:- "Bare (earth)" I would say using the earth for other than earth is against the regulations but this is an interpretation by me and others may see it different.

There is a big difference in saying don't do that, and the guy how did that was doing something against regulations and dangerous. I do make mistakes and I accept that but please where saying some one has got it all wrong at least quote the regulation they are breaking.

I wait to see what regulation it breaks and I do not mean any guides to regulations please quote regulation.
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Postby DIYorNot » Mon Nov 04, 2013 3:08 pm

Using the earth core in twin and earth as phase/neutral would no longer offer two levels of protection as there is now only one layer of insulation to accidental contact.

I am not saying that it goes against any of the regs. however, any competent electrican would not use the earth conductor in twin and earth for anything other than earth.

The earth conductor in standard 3-core flex is sometimes used for phase/neutral if sleeved appropriately at both ends.
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Postby ericmark » Wed Nov 06, 2013 8:45 am

I do agree I would never use the earth wire for anything else other than earth. However I am wary of condemning other peoples work if the house owner was to stop using the electrician because he had tried to be helpful and we on here have said how bad what he has done is that would be counter productive. The guy fixed it and a low cost and without as far as I can see breaking regulations.

Now with flex where it is coloured green/yellow it would be very different that is clearly wrong 514.4.2 states "shall only be used as a protective conductor and shall not be over-marked at their terminations" there is no room to wriggle out of that yet I have gone into a major housing estate and found most houses had class II tank thermostats and the electrician had used the green/yellow for a line wire.

I have myself used both brown and blue as line without over sleeving the blue one yellow flex and I would guess most electricians do! Why yellow flex has brown and blue cores I don't know one would expect to find brown and black with green/yellow as yellow is normally used on 110 volt supplies where there is no neutral. But it would be very easy without having all the facts to criticise an electrician here for not over sleeving the blue neutral cable yet in real terms it's not required as we all know there is no neutral with 110 volt so it must be line 2. So I am wary of condemning some ones work on a forum as we are likely not been given all the facts.
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Postby sophie716 » Wed Nov 06, 2013 3:38 pm

I can only add that the earth wire in the switch box was an entirely separate cable and was not attached to anything.
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