New light fitting - tripping rcd immediately

[SamMcG]

Not an electrician, but have fitted many ceiling light replacements over the years as DIY jobs (badly no doubt!), but have an issue with one today.

Seemingly simple replacement with only a single live (supply is red), single neutral (black) and an earth. Previous fitting was simple so just plugged the new one in the same way.

As soon as I connect the new light to the supply, even though the light trip is set to 'off' on the circuit breaker box, an RCD trips everything in the house immediately.

I'm sure I've got the simple live to live and neutral to neutral mapping correct, so wondering what I've missed here? Presumably it's shorting for some reason?? Any tips appreciated!

 

[SamMcG]

Original Fitting:

 

[SamMcG]

New one:


As soon as I connect the other end as shown below, it trips

 

[monkey5]

Screw through cable?

 

[Andy™]

screwed cable would be my guess

 

[SamMcG]

Ah ok. Possible yeah.

Thanks for the responses.

The cable doesn't have much slack so hard to check.

 

[ProDave]

What is on the other end of the white flex in the 3rd picture?

Assuming the two black 3 pole connectors plug together one of them is connected wrong.

 

[Andy™]

The cable doesn't have much slack so hard to check.

not hard at all... check for continuity between the screws and the cables....

 

[Andy™]

What is on the other end of the white flex in the 3rd picture?

Assuming the two black 3 pole connectors plug together one of them is connected wrong.

the black connectors look correct. the flex will be to the light. next & a few others use these connectors. does make fitting them easier

 

[SamMcG]

the black connectors look correct. the flex will be to the light. next & a few others use these connectors. does make fitting them easier

Yes it's from Next and you're right, it's the light end side.

 

[SamMcG]

not hard at all... check for continuity between the screws and the cables....

Not sure I follow?

I'm assuming I've potentially gone through the cable in the ceiling which isn't visible and can't tell which way it goes in ceiling. There's a bit of slack, maybe 10cms, which I can pull down and there's no sign of any damage, but may be further up the cable...?

 

[Sharpend]

What is on the other end of the white flex in the 3rd picture?

Assuming the two black 3 pole connectors plug together one of them is connected wrong.

I think wrong assumption, zooming in the plugs are marked LEN on each and wiring appears to correspond?

Andy beat me to it, didn’t refresh before I posted!!

 

[Andy™]

your screws should be electrically isolated from the wiring. check for continuity between screw and conductors. any continuity means the screw is touching a conductor when it shouldnt be

 

[SamMcG]

your screws should be electrically isolated from the wiring. check for continuity between screw and conductors. any continuity means the screw is touching a conductor when it shouldnt be

OK will check this. I'm going on hols tomorrow* so will probably have to wait until next week.

* why did I do this the day before I go away you ask?

 

[Sharpend]

OK will check this. I'm going on hols tomorrow* so will probably have to wait until next week.

* why did I do this the day before I go away you ask?

Because it’s a simple light swap and you’d done loads of them (badly?)
Just a guess

 

[Murdoch]

What happens if you disconnect the lights and turn on the switch?

 

[SamMcG]

What happens if you disconnect the lights and turn on the switch?

Assuming by 'disconnect the lights' you mean to remove the light fitting itself entirely so that nothing is connected there, then nothing happens. I can switch the light on and off with no issue (apart from there being no light of course ).

The problem only occurs as soon as I connect the 2 black connectors you can see in the image and the moment I do so it trips.

 

[Murdoch]

Assuming by 'disconnect the lights' you mean to remove the light fitting itself entirely so that nothing is connected there, then nothing happens. I can switch the light on and off with no issue (apart from there being no light of course ).

The problem only occurs as soon as I connect the 2 black connectors you can see in the image and the moment I do so it trips.

Dare I suggest you connect the old fitting to see if that trips the circuit.

You could have a dodgy fitting

Where did you get them from?

 

[Andy™]

Assuming by 'disconnect the lights' you mean to remove the light fitting itself entirely so that nothing is connected there, then nothing happens. I can switch the light on and off with no issue (apart from there being no light of course ).

The problem only occurs as soon as I connect the 2 black connectors you can see in the image and the moment I do so it trips.

that kinda suggests the light fitting is faulty

 

[SamMcG]

Thanks both.

I will try the other fitting next week to double check.

Would be ideal if it's a faulty fitting as I'm not to blame!