LED Bulbs won't work together on same circuit.

[westward10]

I think you mean parallel?

 

[FatAlan]

I think you mean parallel?

I meant series, but thinking about it now you're saying that the LEDs only work when there's a filament bulb there...although it could be that 2 LEDs in series as apposed to parallel might not work due to the drop in current.

 

[Richard Burns]

Since it is not a transformer then I would move on to the situation were there is a slightly loose connection or a contamination in the wiring generating a small resistance. When the low current drawn by the LED bulbs is switched on there is not enough power to get them to operate, when the higher current is drawn with the filament lamps then this can overcome the resistance and "burn" a current path for operation. I have seen this in a socket that would run an electric blanket but not a lamp; the wires were coated in the green goo and not secure in the terminals, once they were clean and correctly terminated all was fine.
I am sure my explanation is slightly flawed but the effect is the same.
re-terminate all the conductors in the ceiling roses and switch and see if this resolves the problem.
The bulbs will be connected in parallel, even though there is a wire from one to the other the two cores connected to the same core of the wire means they are a parallel connection.

View attachment 35868

 

[Fullerbull]

Right guys, here is another piece of info. The bulb nearest to the switch is filament, the other is LED. Switch on and both light. Removed filament bulb (nearest the switch) and switched on: the remaining LED (farthest from switch) flickered and would not light. Put filament bulb back and both lights work again. The filament bulb will work on its own in either holder with nothing in the other holder. The LED won't unless the filament bulb is in one holder. It is the same story if I put the LED in the holder nearest the switch. I have just opened a new LED bulb package and inserted the new LED. Same story.

 

[Fullerbull]

Thanks Richard Burns for your suggestion - it sounds plausible. I have a slight problem in getting to the switch because it is partly obscured by a very heavy floor-to-ceiling bookcase and while I can switch on, I can't get at one of the cover screws. I'll have to move the bookcase (no quick/easy task) and examine the switch. In the meantime I'll have a look at the ceiling sockets and check if they are ok. I'll not be able to do this until this evening, but if I find anything I'll post again.

 

[westward10]

I meant series, but thinking about it now you're saying that the LEDs only work when there's a filament bulb there...although it could be that 2 LEDs in series as apposed to parallel might not work due to the drop in current.

The op said a few posts later they are series.

 

[FatAlan]

If you can, take some snaps. We like snaps. Be careful.. safe isolation.

 

[ImpededLoop]

My guess now would be a duff switch. Otherwise it can only be a poor connection somewhere but I think this would have shown up before.

 

[Andy-1960]

I'd be looking at poor connection in neutral

 

[Fullerbull]

Thanks to all of you for responding to my query. You have taken a real interest and offered some good advice. Sorry about the delay in posting again, but I had a number of other urgent jobs to attend to (like repairing my fence after the recent storms in my area). Anyway, The Problem is SOLVED. Hurrah! Today I examined both ceiling roses ('cos that was easier being more accessible)and carefully checked and cleaned the first one and followed this by replacing the second one which had a cracked bayonet fitting (plastic) which broke off when I started to take it down. I thought that was problem solved, but it wasn't that, so I spent over an hour removing books and shifting the bookcase to get at the switch. Those of you who have partners will know that inevitably there was then a bit of a delay while my wife vacuumed where the bookcase had been! I could not believe what happened when I unscrewed the switch and pulled it away: the neutral wire just flew out and hung loose. There was absolutely nil contact between the holding screw and the neutral wire (it must have been like that for over twenty years!!). The circuit was being made by the springiness of the wire pressing against the side of the neutral terminal! I tightened it up and Hey Presto the whole thing works fine. I still do not understand why I have never had even a flicker of a problem when using at least one filament bulb in the circuit, but I'm not complaining! The message seems to be that LEDs are very sensitive to resistance in the circuit and require good connections throughout, unlike filament bulbs. Thanks again to everyone for your suggestions.

 

[FatAlan]

Thank for the update. Whoever suggested the loose neutral gets first prize

 

[FatAlan]

Andy-1960 ...I take it you didn't do the original wiring?

 

[ImpededLoop]

Thank for the update. Whoever suggested the loose neutral gets first prize

Sounds like it was the switch wire rather than the neutral.

Glad the OP got the problem sorted.

 

[Andy-1960]

Love to take the praise.. but think it may have been a loose switch wire...

 

[Richard Burns]

Thank you for the feedback, always nice to know how things turned out.
I may have been right about a loose connection, amazing!

 

[FatAlan]

think I need to go back to the trainee thread:

 

[Fullerbull]

Not to blame Andy! Not sure what you mean by switch wire rather than neutral. Both the roses and the switch only had a single red (live) and black (neutral) plus earth, which is not like any other circuit in the house. So how the rest of the circuit is wired I do not know. It was put in about 30odd years ago and I was working in those days so didn't see it installed.

 

[Andy-1960]

Not to blame Andy! Not sure what you mean by switch wire rather than neutral. Both the roses and the switch only had a single red (live) and black (neutral) plus earth, which is not like any other circuit in the house. So how the rest of the circuit is wired I do not know. It was put in about 30odd years ago and I was working in those days so didn't see it installed.

If you only have 2 cores at the switch, one must be live and the other must be a switch wire, very often in a 3 plate lighting circuit (see pic), a twin and earth cable run to the switch is used like this with the red core being the live feed to the switch and black core used as the switch wire. If you have the same at the ceiling rose and the red has become the switch wire and the black is the neutral... It looks like there may be junction boxes somewhere...

View attachment 35966

 

[Fullerbull]

Thanks Andy - there could well be junction boxes elsewhere. Like I say I didn't see any of it go in. Furthermore the builder went bust in the middle of the job, which meant that a number of things were not as expected!