No power through ceiling rose

[smartin1612]

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?

 

[smartin1612]

Because you're working with Mains electric and wiring plugs etc when you could have used your multimeter instead.

Again, what makes you think I haven't already tested these. Can I suggest a trip to Specsavers

 

[mainline]

Again, what makes you think I haven't already tested these. Can I suggest a trip to Specsavers

You obviously didn't do any resistance testing because if you did, you would have known if there was a short before putting mains voltage on it.

 

[DPG]

OP, did the fuse blow or the MCB trip?

 

[mainline]

Again, what makes you think I haven't already tested these. Can I suggest a trip to Specsavers

I can't see anything in your posts suggesting that you have tested anything with any sort of decent tester.

 

[westward10]

Can we not turn this into an argument.

 

[smartin1612]

So for the sake of this conversation.
Two of my rooms had a three-spot spotlight fitted - not a great look for a bedroom so having put up with them for 10 years, we decided at the first opportunity to remove them, but suffice to say, we have known for many years that the ceiling roses and the attic juntion boxes have worked fine.

Knowing that there is nothing wrong with the circuitry before I began the work, it was more than a little jarring when switching from spotlights to pendants, the lights just would not work.

I didn't feel it necessary to test with a multimeter as the pendants would not work, but the re-instated spotlights did. Tell me, if you had a light in your hand (that you no longer wanted) that was working, and just a basic ceiling pendant, that wasn't, which would you suspect?
The clearly working ceiling rose, junction boxes and light switches were almost certainly not the problem, especially as with the pendant fitted and the switch off, my circuit tester is reading no charge, but with the light switch on, and bulb in, the circuit test is registering even though the bulb was not illuminating.
Although I didn't explain all of the tests that I had tried to this point, I did explain on line 2 of my opening post: "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)"
Which I thought to be enough to explain to you all that I doubted the lighting circuit as this was working when I refitted the spotlights.

As for your comments @mainline, about working with mains electricity, by the time I had opened this thread, I had determined the problem to be releated to the pendant, specifically the lampholder; so shifting my troubleshooting there, I wired the spotlights to a plug and tested on a wall outlet - success, the lights lit.
Replacing the spotlights with the pendant, and again, just the same as at the ceiling, the bulb would not light even though my circuit tester was indicating voltage - so it is a problem with the lampholder but what?

Firstly, I had moved the terminals closer to the bulb, this is a screw fitment so live is at the bottom and neutral to the side, but this made no difference. So I moved the neutral further away from the bulb, re-testing, the bulb lit!
These seem different from normal E27's as they have two terminals, one for live, one for neutral, instead of the usual arrangement of live terminal, and neutral base:

So there's answer, the neutral terminal was - was what exactly? Too close? How close to a screw-fitment is too close? It still has to contact the bulb in order to complete the circuit, and for me, it was only once I moved the neutral terminal further away from the bulb did the bulb light.
Unless, as the two terminals inside the lampholder are fitted very closely, they were somehow shorting, I'll levae you all to work this one out. Suffice to say, they are working now and both fitted back to the ceiling.

One other point though, looking for the above image just so you could see the terminal layout, the only one I could find was that customer image on B&Q's website, in the reviews section (https://www.diy.com/departments/bg-white-e27-light-pendant-set/5050765170932_BQ.prd); furthermore, many other customers are complaining that the pendants don't work, presumably like me and this other customer, it was because of a terminal problem.

Please though, do not assume non-electrical knowledge just because I didn't explain everything I had done, instead missing the parts that didn't seem relevant. I too am a forum lead and forum ambassador for a different forum, we are continuosly requesting users to get the balance right - too little information, and were stuck with a mass of questions of "have you done this, have you done that"; but too much, and whilst it is very useful, it if often too much of an overload to try to identify the cause.

SMartin

 

[davesparks]

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.

That's not a short circuit, that's a loose connection.

If it was a short circuit it would have made a loud bang and left an obvious burn mark.

It sounds like you have a faulty lampholder so you should return it for replacement under warranty.

 

[davesparks]

, I can only assume that neutral was contacting live, although the rcd wasn't tripping out so still trying to work that one out

An RCD will not trip on a live to neutral fault, that is not what it is designed to do.
An RCD will only trip on faults which cause current to flow to earth.

And MCB or fuse will operate on faults between live and neutral.

 

[smartin1612]

That's not a short circuit, that's a loose connection.

If it was a short circuit it would have made a loud bang and left an obvious burn mark.

It sounds like you have a faulty lampholder so you should return it for replacement under warranty.

The part that confuses me. I am just as confused for the lack of short-circuit noise and the clear indicator on the lamp-holder of a burn, but I'm also confused on the loose connection: how could it be loose when the terminal was pressed hard against the bulb. And, all cabling was tight.
Only once I had loosened the connection by pulling the neutral terminal away from the bulb did the bulb light.

They're only £3.84 from B&Q, if anyone wants a fun 10 minutes.

 

[smartin1612]

Looks like my current message is awaiting mod approval (probably on account of my including the link to B&Q):

So for the sake of this conversation.
Two of my rooms had a three-spot spotlight fitted - not a great look for a bedroom so having put up with them for 10 years, we decided at the first opportunity to remove them, but suffice to say, we have known for many years that the ceiling roses and the attic juntion boxes have worked fine.

Knowing that there is nothing wrong with the circuitry before I began the work, it was more than a little jarring when switching from spotlights to pendants, the lights just would not work.

I didn't feel it necessary to test with a multimeter as the pendants would not work, but the re-instated spotlights did. Tell me, if you had a light in your hand (that you no longer wanted) that was working, and just a basic ceiling pendant, that wasn't, which would you suspect?
The clearly working ceiling rose, junction boxes and light switches were almost certainly not the problem, especially as with the pendant fitted and the switch off, my circuit tester is reading no charge, but with the light switch on, and bulb in, the circuit test is registering even though the bulb was not illuminating.
Although I didn't explain all of the tests that I had tried to this point, I did explain on line 2 of my opening post: "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)"
Which I thought to be enough to explain to you all that I doubted the lighting circuit as this was working when I refitted the spotlights.

As for your comments @mainline, about working with mains electricity, by the time I had opened this thread, I had determined the problem to be releated to the pendant, specifically the lampholder; so shifting my troubleshooting there, I wired the spotlights to a plug and tested on a wall outlet - success, the lights lit.
Replacing the spotlights with the pendant, and again, just the same as at the ceiling, the bulb would not light even though my circuit tester was indicating voltage - so it is a problem with the lampholder but what?

Firstly, I had moved the terminals closer to the bulb, this is a screw fitment so live is at the bottom and neutral to the side, but this made no difference. So I moved the neutral further away from the bulb, re-testing, the bulb lit!
These seem different from normal E27's as they have two terminals, one for live, one for neutral, instead of the usual arrangement of live terminal, and neutral base:

So there's answer, the neutral terminal was - was what exactly? Too close? How close to a screw-fitment is too close? It still has to contact the bulb in order to complete the circuit, and for me, it was only once I moved the neutral terminal further away from the bulb did the bulb light.
Unless, as the two terminals inside the lampholder are fitted very closely, they were somehow shorting, I'll levae you all to work this one out. Suffice to say, they are working now and both fitted back to the ceiling.

One other point though, looking for the above image just so you could see the terminal layout, the only one I could find was that customer image on B&Q's website [BG White E27 Light pendant set], in the reviews section; furthermore, many other customers are complaining that the pendants don't work, presumably like me and this other customer, it was because of a terminal problem.

Please though, do not assume non-electrical knowledge just because I didn't explain everything I had done, instead missing the parts that didn't seem relevant. I too am a forum lead and forum ambassador for a different forum, we are continuosly requesting users to get the balance right - too little information, and were stuck with a mass of questions of "have you done this, have you done that"; but too much, and whilst it is very useful, it if often too much of an overload to try to identify the cause.

SMartin

 

[westward10]

It doesn't appear that a short has taken place I suspect the problem to be poor quality of the component. Modern ES holders are not polarity biased, just for info.
Which lamp holder is giving the problem the left or right.

 

[smartin1612]

It doesn't appear that a short has taken place I suspect the problem to be poor quality of the component. Modern ES holders are not polarity biased, just for info.
Which lamp holder is giving the problem the left or right.

Thank-you I am at a loss to explain it, and with the innards shrouded by the bulb, I cannot see what is happening. I could've resolved this last week had I realised the problem was with the holder rather than the lighting circuitry, but I've had to wait for a day with daylight to work on this once more.
Really frustrating though

 

[mainline]

Thank-you I am at a loss to explain it, and with the innards shrouded by the bulb, I cannot see what is happening. I could've resolved this last week had I realised the problem was with the holder rather than the lighting circuitry, but I've had to wait for a day with daylight to work on this once more.
Really frustrating though

I wasn't being rude btw i was trying to make the point that had you used a multimeter you wouldn't have had to wait 7 days and could have found where the fault was in a few minutes.
The item you are using for doing testing is unsuitable to say the least.

 

[brianmoooore]

At a guess, the neutral contact for the lamp was contacting the insulating section on the bottom of the lamp, and was being bent inwards, towards the live contact and centre terminal of the lamp, as it was screwed in, instead of sliding up the side of the lamp base onto the threaded section.
Unscrewing it a little brings the neutral contact just into contact with the lower edge of the threads.

 

[ipf]

Baffling how something so simple could turn into a Commons Debate.
Get a spark in for 5 minutes.