LED Bulbs won't work together on same circuit.

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Fullerbull

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I have two lights on same circuit served by a single switch. Two filament bulbs work fine. One filament bulb plus one LED work fine in either position. Two LEDs will not light up (normally). If I switch on they momentarily light up, then go out, with one bulb nearest the switch going on and off rapidly. Very occasionally they will both come on when switched on (about twice in six last months). Also very occasionally (again about twice in six months)they will come on after many attempts in switching on and off. Anyone got any ideas?
 
Thank you guys for all your replies. There have been no alterations. Filament bulbs work fine either as a pair or if only one is fitted with the LED bulb( in other words in any combination, in either position, as long as one of the bulbs is filament). The bulbs I am using are TCP LED, 60W, Bayonet fitting, working off 240volt mains. I have tried re-seating the bulbs several times to check good contact in the socket. In any case there is always a good contact when an LED bulb is used with a filament bulb in the other socket!
 
I have a similar arrangement in the kitchen which is adjacent to the room with the problem (study). In the kitchen I have the same set-up i.e. a single switch (non-dimmable)in a two bulb 240 v circuit. I use the same type and manufacturer LED bulbs, but the fitting is ES. The bulbs in the kitchen work fine (several months of operation) However, I don't think the type of fitting is the problem, because I can get the bulbs in the study to work, with no fiddling around trying to get good contact in the socket, provided one of them is a filament bulb - as described above. I am baffled!
 
I have an upstairs bedroom, again with the same arrangement - One switch, two bulbs. The sockets here are bayonet. I can get the two LED bulbs to work in that bedroom no problem. However, I use filament bulbs there because the LEDs I have are too bright for a bedroom. I'll have to wait for them (filament bulbs) to fail then fit lower wattage LEDs.
 
Tis a mystery. Does it matter which holder you put the LED lamps in when you use one LED and one filament lamp.
 
I swapped 2 bulbs between.2 identical fittings earlier this week... They both worked after they had been swapped, but only 1 before.

These were bayonet fittings!

Odd, but I put it down to crxp manufacturing standards of the bulbs.
 
60W sounds high for an LED. Is it 60w equivalent?
Have you tested both bulbs else where? Could it be that just one is defective.
 
Nope! I can put either one in either holder. The only criterion for them to work is that one of them must be filament. I know that this is an intractable problem and I have given it a lot of thought though I am not a Sparky (I was an engineer in a previous life). I think what I'll do is wait until I have my extension done in a few months time and get the electrician who does the wiring to check it all out and maybe re-wire. I suspect that ultimately we'll get it to work, but I'll probably never know the reason! If I do, then I'll post it. Thanks to all who have responded - I appreciate your time and thoughts.
 
Sorry to the last two responders. I posted before I had seen your queries. 60w is the equivalent. Sorry I should have made this clear. The actual wattage for each LED bulb is claimed to be 10W with an output of 810 lumens each. All LED bulbs tried in this circuit and have been tried in other circuits. All are faultless. Odd that Murdoch had a similar problem. I shall go through my stock of LED bulbs just to be sure, but since the ones that don't work in the study do work elsewhere gives me little hope that I will find this to solve it.
 
The LED is definitely a 240v it actually says 220-240v 50/60 Hz. They are connected in series, but then so are the ones in the kitchen and bedroom and they don't fight. However, it does feel as if they are in conflict though that is an emotion not a measurable fact!
 
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
 
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.
 
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.
 
FatAlan said:
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.
Click to expand...
The op said a few posts later they are series.
 
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.
 
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.
 
Fullerbull said:
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.
Click to expand...

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
 
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!
 

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