Lighting fault on downlights

[Darren Cox]

Hi good morning.

I wonder if any one can help me.

Yesterday i replaced a fuseboard at a domestic property and added a few new circuits.

Eveything tested fine until i carried out a functional check on the lighting circuit. Which ever switch i turned on in any of the 5 rooms it would trip the RCD.

So as you do i started to test and investigate and fault find to why this is happening.
After a few hours of taking every downlight down and every switch off the wall. There didnt seem to be anything that wasnt wired correctly.

So i broke the installation down. Found where the 1st feed went to. Then wired the loop to the downlighs in that room straight on to my incoming feed trying to get them on permanently. AGAIN tripped the RCD.

I removed all of the LED GU10 lamps from that room and tried again. This time the circuit and the RCD stayed on. Tried to put one lamp in and AGAIN the RCD tripped.

Tried the same thing in all the other rooms and the same thing....without the lamps it stays on... put any lamp in it trips the RCD straight away.

I ran out of day late and by this time ideas. Has anyone had a similar problem and if so how do i go about rectifying the fault.
Any help would be gratefully appreciated.

Many thanks
Darren

 

[Baddegg]

Neutral in wrong bar....

 

[Bob Geldoff1234]

100% what ^^ he said or a borrowed neutral usually on the 2 way hall/landing lights.

 

[Darren Cox]

The neutral is in the right bar. Double checked that.
Regards to borrowed neutral ive never really come across that. What can i do to rectify this please?

 

[richy3333]

Find it and rectify. Sorry, didn’t mean to sound sarcastic but that’s it in essence. Try putting all the lighting circuits on the same RCD or better can they be terminated into the same mcb? That all supposes the borrowed neutral is off a ‘like’ circuit. Good luck.

 

[Baddegg]

Bobs suggestion is probably best place to start looking...

 

[Darren Cox]

There's only one lighting circuit

 

[telectrix]

if it is a borrowed N on landing light, then it's usually only switching that one light on will trip RCD. as all other lights get their N from the correct N bar, and so there is no imbalance.

 

[contractor999]

I've had a similar situation on a board change,
turned out to be an extra wall light installed on a downstairs lighting circuit, utilising a ' borrowed neutral' from the Ring final circuit immediately above the offending light, installed by a builder who said he knew what he was doing.......
It took me a day to find it after taking up most of the bedroom carpets and floorboards.
Good luck. You'll get a great sense of satisfaction when you do discover the fault.

 

[Darren Cox]

Ok thanks. Theres a few spurs dotted about so i have a look at them and see what's occurring. Im going back there Friday so I'll let you know how i get on.
Thanks for all replies. Much appreciated

 

[Bob Geldoff1234]

Before doing a board change I always turn all the lights on in the house first before switching off the mains(also helps when testing IR during the board change).Then,after the board change,before switching on I test between the 2 neutral bars to make sure there's no continuity.If there is then I switch off the landing light first to see if it clears.It saves running around after you have switched on wondering why it isn't working.