I've found a displaced wire in a double dimmer switch:
All three screws on the right-hand unit seem to be tight so it's not clear where the wire has come adrift from. A quick Google search hasn't turned up an obvious answer so any advice would be welcome. Many thanks.
Sorry, a line got lost...
The obvious location is the empty L2 but obviously I want to be sure.
There look to be two empty L2s. I presume one of the circuits is not working? and if so use the l2 of that particular gang. It is rather strange that you say there are no loose screws (apart maybe from whoever fitted it?)
Bob, thanks for that. No, both circuits are working, each one controlling lights at either end of a long room.
The position of the loose wire suggests very strongly that it come from the right-hand unit, so am I correct in thinking that the RH L2 is the one to use?
Bob, I've just realised that I completely misread your post: Before I removed the faceplate, both circuits were working. Since then, I haven't tried. I'll restore the current and have a tentative experiment...
...and this is the result. With that wire disconnected, *neither* circuit works. And with it put into the RH L2... *neither* circuit works.
So LH L2 perhaps?
With any switch or dimmer, you need a feed and a return. With a double switch, that feed may be shared between them. So a minimum of three wires into the wall in this case.
Your pic shows two dimmers wired in series. There is no way they can be controlling two circuits as is.
My guess is the loose wire should go to either of the terminals with that link wire. And should be obvious by a loose screw. A wire can't pull out of a properly tightened one.
And sad to say, LH L2 didn't work either. Both circuits dead.
What does your multimeter tell you? I'm guessing the loose wire is the live feed & wants to go to 'common' switch terminal, or less likely L1. But that is a guess.
NT
Are either of those lights controlled by another switch? Do all switches of either light toggle the on/off state of *only* the redpective light when operated?
I'm a litte confused why the units have the word "transformer" on them and a "Pri" voltage rating but no obvious seconadry voltage. I'll ignore that for the time being. B-)
Looks to be three T&E's in that box. The upper two connected to the L1's. The wavy line with arrow I'd interpret as the dimmed (and switched?) output but the are strapped together like commons. The lower cable with the adrift wire, is that wire permenantly live? Or does it switch with any involved switch?
Something odd going on, probably some back feeding but I can't work out where if there is no two way switching involved.
Dave,
And your guess is quite correct. I foolishly didn't check the two common terminals for loose screws, but now I have: LH Common was indeed loose and putting the wire into it has restored correct operations.
Many thanks.
NT,
Ah, if I were electrician enough to own a multimeter, I suspect I'd be electrician enough to have worked out the answer for myself.
A correct guess: see my answer to Dave Plowman, above.
Thanks for the reply.
I would guess it is a single live feed for both lights, so it goes in one of the common terminals as a second wire with the strap that joins the two common terminals. Doesn't actually matter which one, but whichever suits best mechanically. If one of the common terminal screws is loose (you said all were tight on the RHS unit) then this is a clue why it fell out, but electrically it can go either end of the separate short brown wire.
Roger,
Your guess is quite right: see my other answers. Many thanks.
I would expect it goes into a terminal along with either end of that bridge wire. it looks like you have one live in, and then two switched lives out. Since the two gang switch has two completely independent switches, the incoming live will need to be distributed to both switches for them to both be able to output a switched live. Hence the link wire.
So on that photo, put it in the left most terminal of the right hand switch.
Dave,
I can't answer your questions, I'm afraid, nor can I shed any light on this:
But I can offer the fact that one of the two units has never satisfactorily dimmed its lights (ceiling mounted LEDs) to a completely off position (and still doesn't). What that means I don't know (simply a matter of the unit being faulty, perhaps?).
Incidentally, I removed the faceplate to investigate whether or not the switch could be moved just a couple of inches to avoid disappearing behind a possible new bookcase; I was hoping there might be enough play in the cabling inside the stud wall. There isn't, but the move could happen if I extended just one of the wires. Is there a recognisedly safe way of doing that?
Many thanks again.
John, thanks for that. You might now have seen my replies just posted above: you're advice was absolutely spot-on.
Don't think so. My expectation would be if you powered that up now, neither light would work. (although take care - that loose wire is the incoming live).
Another clue is the entry point of the wires. The disconnected one comes from a cable that comes up into the back box, and the other two go "up" toward the ceiling.
(you appear to have a less common arrangement with both live and neutral brought to the switch - the neutrals are then communed with the switched wires going out in that Wago terminal, the live feed was then split between one side of both switches, and the other sides carry the switched (and in this case dimmed) live to the light fittings)
They are two way switches, but are just being used single way in this application. The terminal with the wavy line icon is what we would normally know as "COM". L1 and L2 take their usual function.
Might just be a reflection of the fact that some dimmable LEDs have a poor dimmable range. (dimming can also be upset if there is a mix of lamp brands / types being dimmed on the same switch)
If you are leaving the existing box in place (and say putting a blanking plate over it) and installing a new switch to its side, then any kind of terminal is ok - chock block, Wago terminals (like that joining the blue wires in your switch), or crimped extensions are acceptable.
If however you were planning on heat shrinking the wire extensions and then plastering them in, then something "maintenance free" would be required like the wago or crimps.
e.g.:
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