Lighting circuit trips RCD

[Shinner]

Hi
Have recently had a house extension fitted and when the builders connected up their electrics they connected their neutral to the wrong side of my 17th edition consumer unit.
Both RCDs were then tripping.
I spotted the mistake and corrected it, however the RCD which is not on the new circuit side would not reset.
I removed the neutrals from that side and got it down to one lighting circuit.
That circuit contains transformers, so I assumed that they had blown them, however I took them out of the circuit along with any dimmer switches and bulbs, but the RCD will still not make.
Nothing has been changed to this circuit, so I can only assume something has blown that I don't know about.

Any thoughts or ideas as I have no hair left?

 

[kung]

Hi Shinner
Hard to tell without seeing how the lighting is wired have the builders taped into the lighting circuit ? id swop rcd's over and see if its not damaged it if not id then discon lighting and cont/ir checks before moving on.
Regards
Kung.

 

[Shinner]

Thanks Kung
Builders circuit is totally separate on a small consumer unit in the extension.
So can only think when they may have meggered their circuit, as the neutral was on the wrong side it may have caused some damage as I've found most of my bulbs blown.

Have just bypassed my lighting circuit by linking straight to my transformers/downlights in the kitchen and they work fine on there own, so transformers are ok

Sorry
RCD is working fine when lighting circuit removed, so that must be ok.

 

[kung]

Could be when they done their IR test
Only other way is from 1st light discon ongoing and try that then keep adding till you find the fault

 

[Shinner]

Thats what I thought but they said they didn't do it as I found their neutral in the wrong place.

Even if they had, I can't see one IR breaking down the whole resistance of the insulation.

Strange that there is a fault now though after it was working ok before

 

[kung]

Typical builders not testing to bs7671 if they didnt even test prop then i wouldnt trust what they say id do ALL TESTS.
Regards
Kung.

 

[Shinner]

Just done IR checks on my lighting circuit
Line-Neutral >299M
Line-Earth >299M
Neutral-Earth 0M

I can see a problem here!

 

[spark1]

Did you not get an Electrical Installation Certificate off the Builders for this work?
Did you not receive a Building Compliance Certificate from the council for this work /
...If any of the above is a No then I would be very worried....Get back to the Builders if you have not received this paperwork.



spark1

 

[Shinner]

They are coming back next week to complete and having an inspection
But have been concerned as the problem is on my circuit, not theres and they might turn around and say theres is working ok
See where i am!

 

[spark1]

If they have not yet tested their new electrics, as your last comment suggests then they should not have powered up at all...if they have tested , you got the E.I.C

If you have traced the Low IR reading to one of your existing circuits then I dont think they will be investigating that for you..you will have to carry on splitting the relevant circuit until you discover the reason for the low IR....it may well be equipment with electronics in it which have blown after being subject to 500volt IR test. If so you can show them it and see what they say then...but it will be difficult to prove if this is the case...I trust you dont have any rubber insulated cables as these could be damaged by IR tests if in a poor condition.Pay special consideration to any areas where they may have been to in relation to your existing circuits.....

spark1

 

[Shinner]

Thanks Spark1
The builders must have knocked one of my lights as when I took it apart neutral was loose
Is't it nice when there's a simple answer that takes all day to get to!

Thanks everyone for their input

 

[andyd55]

Try checking all your neutrals around the place mate as this will trip the RCD as well.

----------------------


Ops just read you got it sorted!

 

[Scott F]

Shinner I'm very tired so may have misread something .

Have you verified each neutral for each circuit .

Its vey easy to mix them up when feeling the pressure .

Could it be a borrowed neutral on the lights and now your protected by RCD its tripping out ?

Scott

 

[kung]

Thanks Spark1
The builders must have knocked one of my lights as when I took it apart neutral was loose
Is't it nice when there's a simple answer that takes all day to get to!

Thanks everyone for their input

Glad you have it sorted now Shinner ! one of them might have taken the light apart to tap in for the ext lighting but either way you have it sorted now so thats good.
Regards
Kung.

 

[andekoch]

Just done IR checks on my lighting circuit
Line-Neutral >299M
Line-Earth >299M
Neutral-Earth 0M

I can see a problem here!

A Neutral-earth 0M reading can happen if the main earth to the board is still connected when you check the circuit (unless you removed the Earth and neutral of the circuit from the board before testing them.

check that their mounting/ fixings did not pierce your light cable.