Light switch reversed after transformer blew in the ceiling

[picklepass]

So John what do you mean, do I take the red wires from L1 leave them not connected then see if the lights are on?

 

[JohnW2]

If I made a mistake in the wiring wouldn't it trip the trip switch.

Not necessarily.

I have connected the transformer and to the ceiling electrics exactly as it was previously, could it be the transformer????

I very much doubt that it could be the transformer. As I said before, if you really are sure that the operation of the switched changed, I think you should seek the assistance of an electrician.

Kind Regards, John

 

[riveralt]

For example, would you regard it as particularly 'safe' (or, at least, desirable) if the light is being switched off by shorting the output of it's (always powered) 'transformer'? If it were your house, would you be happy to leave such a situation possibly persisting?

I'm trying to get my head around this so is that what you think has caused switch 'transformation' to happen here?

This is precisely why I suggested the 'step by step' approach (rather than jumping straight to the L1/L2 swap). If the light remained on when one side of the switch was disconnected, one would know that something very odd, and potentially worrying, was going on.

So the answer to the OP is not to put the two reds back to L2 but to put them in a connector block and see if the light stays on?

 

[stillp]

Personally I think that's a waste of time. You need to check the wiring of the circuit for this ligh - the Wiki will show you how the circuit should be wired.

 

[JohnW2]

So John what do you mean, do I take the red wires from L1 leave them not connected then see if the lights are on?

Yes. In fact, it would be simpler to disconnect the other (black) wire from the Com of this switch (since there is only one of them) - BUT you need to do something safe with the wire you remove (like put it into a bit of connector block). Unless something is very wrong, the light will be off when you disconnect one side of the switch.

Kind Regards, John

 

[JohnW2]

For example, would you regard it as particularly 'safe' (or, at least, desirable) if the light is being switched off by shorting the output of it's (always powered) 'transformer'? If it were your house, would you be happy to leave such a situation possibly persisting?

I'm trying to get my head around this so is that what you think has caused switch 'transformation' to happen here?

Nope, I don't think that. Frankly, I'm not convinced that the 'transformation' ever happened. However, some people have suggested that mechanism and, without further investigation, neither you nor I can completely discount it.

So the answer to the OP is not to put the two reds back to L2 but to put them in a connector block and see if the light stays on?

Exactly - or, as I've just written to him do it with the single balck instead. That's the necessary 'further investigation'. If,a s expected, the light is off when one side of the switch is disconnected, I fear that I'm going to be close to concluding that there probably never was any 'switch transformation'.

Kind Regards, John

 

[stillp]

So John what do you mean, do I take the red wires from L1 leave them not connected then see if the lights are on?

Yes. In fact, it would be simpler to disconnect the other (black) wire from the Com of this switch (since there is only one of them) - BUT you need to do something safe with the wire you remove (like put it into a bit of connector block). Unless something is very wrong, the light will be off when you disconnect one side of the switch.

Kind Regards, John

NO!
Don't try different combinations of wiring so that a guess can be made about what's wrong. Trace the wiring, with the circuit switched off.

 

[JohnW2]

NO! Don't try different combinations of wiring so that a guess can be made about what's wrong. Trace the wiring, with the circuit switched off.

I really don't agree. I'm not suggesting 'suck it and see' attempts at different wiring combinations (which is essentially what he did in response to riveralt's instructions) to see what happens. I'm talking about disconnecting a wire as part of a systematic fault-tracing exercise. For the OP to 'trace the wires' would be far from straightforward.

As I've said to him, more than once, I think that the OP has either got to refresh his memory and admit that the switch functionality hasn't ever changed (until he followed riveralt's instructions), or else get an electrician.

Kind Regards, John

 

[stillp]

I'm not suggesting 'suck it and see' attempts at different wiring combinations (which is essentially what he did in response to riveralt's instructions) to see what happens. I'm talking about disconnecting a wire as part of a systematic fault-tracing exercise.

I really don't see the difference. If the OP doesn't understand why you're asking him to do that, then it is essentially just guesswork.

Picklepass, are you sure you didn't remove the switch at some stage and put it back upside-down?

 

[JohnW2]

Picklepass, are you sure you didn't remove the switch at some stage and put it back upside-down?

As you will have seen, back on Page 1, I wrote:

If it is a one-way switch, the only thing I can suggest is that the OP removed the switch for some reason and then refitted it upside down!

... and the OP responded:

The light switch was never touched.

Kind Regards, John

 

[securespark]

I don't recall seeing all of the wiring in the ceiling, just the neutral loop and switchwire.

It has to be worth checking those connections are correct. The only other thing I would do as a spark is IR and EFLI tests. I have to assume (I know, I know!) the IR is OK because the CPD is not failing. On a DIY level, the earth loop could be tested by checking continuity between the ceiling light and the switch then between the switch and a socket, having first tested the socket with a socket and see.

 

[picklepass]

Been in the house for 25 years and as far as I know if it had been turned upside down we would have moved the red wires to L1 so it came on the same as the other light switches, and definitely not been touched since the light popped.

 

[securespark]

Could there be any truth in what mfarrow said?

How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth?

We have been scratching our heads for days now, trying to come up with a logical electrical explanation for the switch problem. We have not found one.

It is in my opinion, and this is not a dig at the OP, that the switch has always been wired that way, and that its location next to a two-way switch, which may too normally operate in reverse, has caused it to never be noticed until the testing of such arrangement, following replacement of the transformer, resulted in a bit of thinking and realisation that something wasn't 'quite right'.

 

[stillp]

OK, so the switch has definitely changed its direction of operation, and hasn't been inverted. The transformer doesn't know which way up the switch is, it only knows when it is getting current. There is no fault on the transformer that would result in the switch changing its direction of operation. Therefore either you've wired it up wrong, or it was wrong before and you've corrected it.

So, the input (primary) of the transformer needs to be connected to a neutral and to a switched live from the switch. The output (secondary) side needs to have 2 wires going to the lamp. Is that the case?

 

[JohnW2]

Could there be any truth in what mfarrow said?

As I've been writing (and asking) all day, it's very tempting to think so - but the OP continues to assert that the operation of the switch has changed, despite the switch never having been removed or touched, so I suppose we have no choice but to believe him - even though that leaves us with a very odd situation to contemplate.

Kind Regards, John