Newby DIYer, replacement light fittings trip the MCB

[Freddie]

Hi All,

absolutely aware of my own limitations as a diy' er and limit myself to replacing fittings rather than new installations.

Replaced 4 x 240v GU10 downlighters in the bathroom(ceiling 3m high) and when I turn the light switch on , the MCB trips all lights in the flat. before I replaced the fittings, I never had an issue.

1 gang light switch feeds a 1mm cable up to the ceiling and lights are connected in series, used new cable, connecting all the lives together, all the nuetrals together and earths together.

Have I missed something?

 

[Rosco]

A very common and dangerous mistake, my money is on one of those neutrals being a switch live, if this is within your limit as you say do your have the correct equipment to test for this?
Also a bathroom is a special location.

 

[Rosco]

Apologies just re-read your post which says that it’s switched fed so you have a neutral at the switch

 

[GeorgeCooke]

1 gang light switch feeds a 1mm cable up to the ceiling and lights are connected in series, used new cable, connecting all the lives together, all the nuetrals together and earths together.

Have I missed something?

That is NOT in series then, it is in parallel (which is correct).

 

[littlespark]

You'll just have to double check each connection and if that doesn't find a problem, employ an electrician with suitable fault finding equipment.

Are you central Edinburgh? kind of out of my way but nice drive up the coast

 

[westward10]

Apologies just re-read your post which says that it’s switched fed so you have a neutral at the switch

I think you were correct in the first place.

 

[Octopus]

Have I missed something?

testing, competence and knowledge?

 

[The Ghost]

Could you drop the lights and take some pictures? It may help to identify anything you may have missed. When you say the "...MCB trips..." do you mean the MCB or RCD, you do have RCD protection?

 

[johnduffell]

Classic lighting error, as above one of the blues must have been missing a brown sleeve as it's a switched live. Are the lights on when the switch is off?
Do you have the before and after photos of the wiring?