Moving A Ceiling Light On Ceiling Help!

[davidmichael]

Good evening a query for UK someone kind enough to answer a DIY query.

I am refurbishing a flat and was asked by client to move a ceiling light to centre of ceiling as the lights in three bedrooms were positioned in non central positions.

As the ceiling has 5mm of plaster and then concrete I traced a line from the existing ceiling light junction box following the vertical and horizontal rule. So in essence the line was parallel to the wall. I used a machine to create the groove which is roughly 15mm deep and then fitted a 3 core 1mm wire cable to fix to the existing light junction box to new location on ceiling. Then cemented in the cable with quick set cement. It then occurred to me that this job may have to be done by a qualified sparky or signed off by one. I am also wondering if the cable needs to go inside a metal tube. Can someone help me clarify this please.

Thanks!

 

[Andy™]

so youre a DIYer posing as an electrician and charging your customer for it?

and yes, that modification will need a minor works cert

oh, and i hope you have taken the structural integrity of the ceiling into account now that you have hacked away at it?

 

[NozSpark]

I'd have used some "guardian" type cable at least

 

[kerching]

I would NOT have cut out the ceiling...if it is structural then there could be "issues"

If i was unfortunate enough to have to do this job, then

Chase ceiling plaster to wall

Chase cable into top of wall

Along wall, chase back in to ceiling plaster

Gob up

Ceiling plaster must be deep.enough if there are already cables there, surely?

Taking into account safe zones, RCDs etc

Just being one of a million reasons why I do not do domestic unless absolutely nexessary

 

[davidmichael]

Thank you all for chipping in. Andy def not posing as an electrician my intention was only to chase the ceiling and then to get a sparky to do the rest but my helper wired in one cable and then I told him to wait until we found out the score from you pros so thanks! Okay so had no idea about structural issues here. The existing ceiling wiring appears to be embedded quite deep. As even after cutting this groove to a depth of 10-15mm we did not touch the existing cabling even though we crossed it a few times.

Thank you NozSpark so you would use armoured cable for this. And a minor works cert. Hmmm back to the drawing board!!!

 

[NozSpark]

No , not armoured as such

It's a BS8436 cable which has an aluminium shield....

 

[Sidewinder]

Definitely MWC.

Seconded the potential for structural issues.

The existing wiring could be in pre-made ducts embedded in the pour.

 

[kerching]

On occasions I have seen cables threaded through the blocks in a Bison "block and beam "floor....i never thought that was a good idea!

Just saying

 

[davidmichael]

Thank you for the replies. I emailed some pics of ceiling grooves with one attempt at wiring to my qualified electrician and he said that it appears to be legal providing the circuit is RCD protected. And that he will sign it off for me and complete the MWC if IF it passes all the tests.

I tried the RCD by wiring live and neutral together and then live and earth but on both attempts it was the Lighting fuse which tripped and not the RCD don't know what that means do any of you know?

I agree that trunking would have been optimal but I didn't want to make a deeper groove in the concrete than necessary but may well take up NOz Sparks suggestion of a BS8436 cable. Will go check the thickness now. THanks to all who have taken the time to respond.

 

[Murdoch]

Thank you for the replies. I emailed some pics of ceiling grooves with one attempt at wiring to my qualified electrician and he said that it appears to be legal providing the circuit is RCD protected. And that he will sign it off for me and complete the MWC if IF it passes all the tests.

I tried the RCD by wiring live and neutral together and then live and earth but on both attempts it was the Lighting fuse which tripped and not the RCD don't know what that means do any of you know?

I agree that trunking would have been optimal but I didn't want to make a deeper groove in the concrete than necessary but may well take up NOz Sparks suggestion of a BS8436 cable. Will go check the thickness now. THanks to all who have taken the time to respond.

Are you being serious?

 

[davidmichael]

ok so it was not the thing to do. Take into account that there are no appliances in the flat and all other fuses were off. Wired together as in just touching briefly.

 

[Andy™]

ok so it was not the thing to do. Take into account that there are no appliances in the flat and all other fuses were off. Wired together as in just touching briefly.

next time you do something so stupid, make sure you are the only person anywhere near so its only yourself that you can kill through your incompetence

 

[davidmichael]

Why not be a little more constructive and tell me how you would have tested it. There was no one anywhere near the wiring.

 

[bluetobits]

Why not be a little more constructive and tell me how you would have tested it. There was no one anywhere near the wiring.

You could have used an RCD tester

 

[davidmichael]

Thank you bluetobits does this check wether a circuit is RCD protected or wether an RCD is faulty?

 

[ProDave]

An RCD tester, which any self respecting sparky will have, tests the operation of the RCD, that it trips at the correct current within the prescribed time.

Even the little test button on them does that in a limited form, by introducing an imballance or leakage, though that won't tell you how long it took to trip and at what actual current it tripped.

Shorting it out with a bit of wire is just frankly a way to kill yourself.

 

[davidmichael]

Thanks Pro Dave well let me assure you Monday a self respecting Sparky is going to be onsite but he wanted to know beforehand if the lighting circuit in question  was RCD protected so would be keen to know how you would have tested that. Like I said no one was in the vicinity of where the wires were touching. I was next to the consumer unit and just flicked the master fuse on and off but long enough to see if the RCD had tripped. 

 

[ProDave]

You test whether the lighting circuit is rcd protected by first foing and having a look at the consumer unit.

If there's any doubt, connect the rcd tester to the light fitting and try it. That only introduces a small current inmallamce and it will either trip and tell you the trip time, or it won't trip and tell you fail.

Introducing a L-N short will NOT trip an rcd. It will trip the mcb as well as making a big bang.

If you really are not sure then  a Neutral to earth short will in all probability trip an rcd (certainly if there is any load on the circuit) but that's definitely not an approved test method.

 

[davidmichael]

ProDave very much appreciated. I recall you helped me with a different issue too remember the vintage chandelier?

Now it all makes perfect sense. And I see the error of my ways. Thankfully there are people who have a little more patience for DIYers like me. I have done a basic 2 day training in domestic electrics sponsored by my boss when I was working full time in property maintenance and I recall that we covered this but as it was a while back I simply forgot!! No excuse I know and thank god we have you guys.

 

[Blue Duck]

ProDave very much appreciated. I recall you helped me with a different issue too remember the vintage chandelier?

Now it all makes perfect sense. And I see the error of my ways. Thankfully there are people who have a little more patience for DIYers like me. I have done a basic 2 day training in domestic electrics sponsored by my boss when I was working full time in property maintenance and I recall that we covered this but as it was a while back I simply forgot!! No excuse I know and thank god we have you guys.
 

https://youtu.be/LFuYIi5-igc?t=2m35s