No power through ceiling rose

smartin1612 · Dec 17, 2022

Hello all,

I'm replacing a 3-bulb spotlight with a standard BG ceiling rose but upon connecting, the light won't turn on; the problem is, I can't see why.
We can handle the wiring shortly, but after a day or two of testing - wiring the spot back on, test (it works), replacing with the ceiling rose (it doesn't work), I finally gave up and wired the spotlight to a plug and tested - dropping the 13A down to a 3A first.
The spotlight predictably worked as expected, but upon switching over to the ceiling rose, using the same bulb as the spotlight - it's a 7w bulb, I'm not getting anything, although I am registring power both on the cable terminals and, the light terminals, just no light. It's as though the light terminals are performing a huge resistence that the power could not overcome it and light the lamp.

I have already gone through the motions of junction boxes and switches trying to troubleshoot, which came-up blank - even to wiring the rose direct to the light cicuit and the junction box in the attic [we're still on junction boxes for the lighting circuits rather than using the rose loop] to bypass the switch [using the RCD as a switch], and predictably, I got nothing, hence the direct to wall-outlet approach as a last resort.

Any ideas?

westward10 · Dec 17, 2022

Can you show a picture of the wiring.

smartin1612 · Dec 17, 2022

westward10 said:
Can you show a picture of the wiring.

What the plug circuit?

westward10 · Dec 17, 2022

No the ceiling rose.

smartin1612 · Dec 17, 2022

westward10 said:
No the ceiling rose.

Yes the ceiling rose connected to the plug.
You wouldn't need to see the wiring on the ceiling as this isn't what needs to be troubleshooted.

westward10 · Dec 17, 2022

You say when connected to the new ceiling rose it doesn't work so can we see the wiring at the rose.

smartin1612 · Dec 17, 2022

westward10 said:
You say when connected to the new ceiling rose it doesn't work so can we see the wiring at the rose.

I also said it doesn't work when I wire it to a plug and connect it to the wall

westward10 · Dec 17, 2022

So are you going to show the wiring or not.

smartin1612 · Dec 17, 2022

westward10 said:
So are you going to show the wiring or not.

Hold your horses, I'm getting them for you. I just wanted to be clear that we were troublshooting the correct items - the lampholder rather than the ceiling circuitry.

westward10 · Dec 17, 2022

Show is as connected when not working.

smartin1612 · Dec 17, 2022

The photos of the connections as requested.

Pic 1 is the spotlight wired to the plug - it is working, no disputing that
Pic 2 showing the 3 terminals of the spotlight connected to the plug - the spotlight is metal so the earth is required
Pic 3 is with the Earth released - just so we know that there is no issues with the earth as the problem lampholder is plastic, it can't be seen in shot, but the spotlight is still illuminated
Pic 4 is the problem lampholder wiring at the lampholder
Pic 5 the lampholder to power cable circuitry - as mentioned above, no earth
Pic 6 - no light - it isn't showing but the plug is powered on - I had intended to include my circuit tester in the shot but my camera was being awkward so I just didn't have enough hands - hence my circuit tester in shot in pic 4
Pic 7, a close-up of the lampholder wiring, just so you can see that we're connected to the correct terminals. It can't be seen from this shot but the light is off (those reflected in the work surface are the kitchen lights), but the power is on.

OnlQQker · Dec 17, 2022

Sounds like the terminals in the lamp are not touching the bulb.

smartin1612 · Dec 17, 2022

OnlQQker said:
Sounds like the terminals in the lamp are not touching the bulb.

Its funny you should say that as they are, I had made absolutely sure of it.

The problem is, as I had just discovered, it was my pc build with an Asrock motherboard from 2005 that prompted me to look another direction

littlespark · Dec 17, 2022

The connections really need tidied up. im not sure if some of those flexes are held in the screws properly, and so much copper showing, they could touch together

OnlQQker · Dec 17, 2022

Are the terminals lining up with the terminals on the bulb.

Midwest · Dec 17, 2022

What about a pic of the wiring at the the ceiling where the luminaire was originally. Or have I got hold of the wrong end of the stick?

smartin1612 · Dec 17, 2022

Midwest said:
What about a pic of the wiring at the the ceiling where the luminaire was originally. Or have I got hold of the wrong end of the stick?

Slightly wrong end of the stick at present as after spending the last couple of days troubleshooting, I've determined the problem to be with the lampholder and not the wires at the ceiling.

If the light works when plugged into the wall, nut not the ceiling, then we know its something else, but currently, as its not working from the wall outlet either, when the original 3-lamp spotlight is, tells me the problem is with the lampholder.

smartin1612 · Dec 17, 2022

littlespark said:
The connections really need tidied up. im not sure if some of those flexes are held in the screws properly, and so much copper showing, they could touch together

I don't care for the connections right now, you are seeing a test cable connected to a wall-plug rather than off the ceiling, as right now, I'm troubleshooting the lamp-holder.
Once I go back to the ceiling, they'll be covered in heat-shrink

smartin1612 · Dec 17, 2022

OnlQQker said:
Are the terminals lining up with the terminals on the bulb.

I believe so, I pulled the terminals up and in a little to ensure the connection is made

westward10 · Dec 17, 2022

So just to clarify the new lampholder does not function at the rose nor the wall outlet but you know the spotlight is good because you have proved this at the old spotlight track.

smartin1612 · Dec 17, 2022

Found it - short circuit!

7 frickin days I've lost to this, with the two main rooms upstairs in darkness, not great for home workers, the amount of meetings I've held looking like something on Halloween...

I made mention of my Asrock pc build back in 2005 - it was terminals:

My Asrock motherboard had a bit too much solder on the back of the circuit board.
It worked outside the case, but the moment I installed it, nothing. No power, no resistance, nothing. No CMOS, no BIOS.
Take the motherboard out, and the pc would fire-up.
Took me two days to resolve, and was only as I was about to send back did I discover it: the screw in the middle of the motherboard was pushing the board down just too much, it was contacting the case and shorting.

Double-checked the terminals of the lampholder and sure enough pushing the netural away a bit, the lamp fired up.

Netural was too close to live and was shorting, though not killing the rcd - gotta look into that.

smartin1612 · Dec 17, 2022

westward10 said:
So just to clarify the new lampholder does not function at the rose nor the wall outlet but you know the spotlight is good because you have proved this at the old spotlight track.

Yes, that's correct

westward10 · Dec 17, 2022

Can you show this apparent short.

smartin1612 · Dec 17, 2022

westward10 said:
Can you show this apparent short.

How do I show the short?

As explained, pushing the neutral terminal further away from the bulb allowed the bulb to fire - obviously I had to make the mod with the bulb out and keep testing until I'd found the sweet spot - too far away annd the neutral wouldn't connect too close, and whilst the bulb would contact, it wouldn't power on.

DPG · Dec 17, 2022

I can't picture where this short was.

Presumably the fuse blew or MCB tripped?

No power through ceiling rose

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