ello all, mother in laws bedroom light has two twin and earth cables coming out of the ceiling. each cable has a black, red and earth. i have wired them into a new light fitting exactly how drawings show, black to neutral terminal black to live switch and reds in loop terminal. one of the blacks has a white dot painted on so i took this to be the switch cable, but when i switched the light on the fuse trips in the consumer unit. i then changed the blacks over but the fuse still trips . help please.
ceiling light problem
- Thread starter Spango
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It would appear that you have done it correctly.
'Assuming' that one of the cables is the supply - Red Live, Black Neutral - there isn't much that you could do wrong to make it trip other than connecting these together.
If it only trips when you turn on the light switch it must be the switched live which is touching a Neutral or Earth.
I can only suggest you make sure that the cables are not damaged where the wires emerge from the sheath.
Other than this some testing will be needed.
'Assuming' that one of the cables is the supply - Red Live, Black Neutral - there isn't much that you could do wrong to make it trip other than connecting these together.
If it only trips when you turn on the light switch it must be the switched live which is touching a Neutral or Earth.
I can only suggest you make sure that the cables are not damaged where the wires emerge from the sheath.
Other than this some testing will be needed.
Is there more than one light that is operated from the same switch, ie when you turn this light on does another one or more light/lights come on?
There are many configurations and methods that make lights work and there is nothing to say that the installer has followed a more normal standard procedure.
So for clarity, when the light is switch on the fuse/MCB trips and not a RCCB or a RCBO?
If you have a second or more lights operating from the same switch and this works with the one you are changing disconnected, I would assume
that they are linked across each other this would mean both reds go together at live and blacks both together at neutral. But only if you have more than one light on same switch.
Other than that it would be guess work, do you have a means of safely testing for continuity and voltage, some like a multi-meter would help greatly.
If you are getting the a trip at the MCB, that would suggest you have connected the live and neutral together, if there was no history of this fault existing prior to the swapping of lights.
But there is a chance that you may have nicked the insulation of the switch live conductor and if the fitting is metal then you will get an live-earth fault.
So check for damage or nicks on the conductors.
There are many configurations and methods that make lights work and there is nothing to say that the installer has followed a more normal standard procedure.
So for clarity, when the light is switch on the fuse/MCB trips and not a RCCB or a RCBO?
If you have a second or more lights operating from the same switch and this works with the one you are changing disconnected, I would assume
that they are linked across each other this would mean both reds go together at live and blacks both together at neutral. But only if you have more than one light on same switch.
Other than that it would be guess work, do you have a means of safely testing for continuity and voltage, some like a multi-meter would help greatly.
If you are getting the a trip at the MCB, that would suggest you have connected the live and neutral together, if there was no history of this fault existing prior to the swapping of lights.
But there is a chance that you may have nicked the insulation of the switch live conductor and if the fitting is metal then you will get an live-earth fault.
So check for damage or nicks on the conductors.
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If it was a switched feed to the fitting in and out (red to red and black to black) then wiring as the OP has would split the neutral onto the lamp contacts.
That would make the neutral open circuit. Would that open the CPD?
That would make the neutral open circuit. Would that open the CPD?
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But it maybe part of number of lights switched across each other, that is why I have asked that question?
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