Light tripping!! Any advice

[young sparky]

Wired a house a while back and just getting around to putting up the main light in the hall last week, (20kg hanging pendant ), there is 3 switch linens on the circuit, outside lights, 6 spots in the hall then the pendant, before installing this light all over lights were working fine and all switching was fine but after installing it the MCB is tripping, the main hanging pendant will turn on but as soon as you turn the light off the MCB trips, cannot understand why light is staying on but then suddenly trips when the switch is turned OFF any ideas or anyone had a problem similar, really don’t fancy taking this light down as it was a serious hassle to put up in first place in an open hallway, the light is two way wit an intermediate switch but all seems fine at the switches, I disconnected the light from the roofspace JB and connected in a lamp drop to make sure all was working and the lamp drop is turning on and of as required from all switches with no MCB tripping

 

[Octopus]

Are the lights 230v or is there a transformer involved?

 

[MJPD29]

this might sound stupid, but when you screwed up the light did you nick any cables with the screws?

 

[Jamie']

Did you test the property?

 

[Pete999]

Wired a house a while back and just getting around to putting up the main light in the hall last week, (20kg hanging pendant ), there is 3 switch linens on the circuit, outside lights, 6 spots in the hall then the pendant, before installing this light all over lights were working fine and all switching was fine but after installing it the MCB is tripping, the main hanging pendant will turn on but as soon as you turn the light off the MCB trips, cannot understand why light is staying on but then suddenly trips when the switch is turned OFF any ideas or anyone had a problem similar, really don’t fancy taking this light down as it was a serious hassle to put up in first place in an open hallway, the light is two way wit an intermediate switch but all seems fine at the switches, I disconnected the light from the roofspace JB and connected in a lamp drop to make sure all was working and the lamp drop is turning on and of as required from all switches with no MCB tripping

Looks like that light you don't want to take down will need looking at, as others have said have you done any testing?

 

[Wilko]

Two way switch wired with a traveller to N ?

 

[telectrix]

Two way switch wired with a traveller to N ?

no travellers. they'd have nicked and weighed in the chandelier before now.

 

[Wilko]

Makes a change from connecting them to L

 

[Richard Burns]

#6 was my first thought, so IR test the switching cabling to E and N with the switches in all positions.
If you have access to the junction box in the roof space for the pendant then test for IR on the connections to the light fitting just in case #3 is correct.
The highest current will be drawn when the arc is sustaining across the opening light switch so if the problem is relating to a specific one of the three switches then try temporarily wiring that pendant switch to new switch and see if the problem recurs. Perhaps even just wiring it to a one way switch (if you have wired it in 3 wire wiring) from the supplied switch and see if the problem is related to the three way wiring.

 

[ipf]

20kg ....one heavy pendant is that!
How many lights and what type and voltage are involved/
transformer?...led, or what?
What size and type of breaker? Some recommend C type.

 

[Jay Sparks]

If the light is on a 1G 2 way switch, check that the terminal screw from the unused way isn't sitting on/touching the lug/back box.

I had that problem on an outside light years ago. Worked ok when on, but tripped as soon as they turned it off. As soon as I pulled the switch plate forward, the little terminal screw fell out and I could see where it had been touching/arcing on the bottom lug of the back box.

Jay

 

[young sparky]

Are the lights 230v or is there a transformer involved?

Yea light has quite a large transformer inside with approx 14 lamps dropping, really hoping it wasnt a faulty light but can’t think of any other reason why it would be tripping

 

[happysteve]

Could be a transient spike from the collapsing magnetic field in the transformer when you turn it off suddenly with a switch. Much like a switch start fluorescent. In theory, the breaking switch contact should prevent any extra current from this spike reaching and tripping the breaker, but breaking a contact isn't instantaneous and as @Richard Burns has mentioned there's the possibility of an arc being sustained across an opening light switch.

As per @ipf 's post - what size and type of breaker? If Zs and other factors will allow it, perhaps go to a type C (if not already)? Failing that, perhaps some sort of surge protective device (stubber?) located near the big light?

 

[static zap]

Could be a transient spike from the collapsing magnetic field in the transformer when you turn it off suddenly with a switch......
@Richard Burns has mentioned there's the possibility of an arc being sustained across an opening light switch.

As per @ipf 's post - what size and type of breaker? If Zs and other factors will allow it, perhaps go to a type C (if not already)? Failing that, perhaps some sort of surge protective device (stubber?) located near the big light?

Switch already damaged ,Snubber required.
(has MCB been ruled out for being over sensitive )

 

[ipf]

Yea light has quite a large transformer inside with approx 14 lamps dropping, really hoping it wasnt a faulty light but can’t think of any other reason why it would be tripping

Give some details...breaker and fitting, as previously said. Did you read the instructions fully?
Everybody is surmising.