Reverse polarity in light switch

[katie6]

Hi there,

I have just changed an old 2-gang light switch dating from about the 70s (I guess) with a modern one. Once inside I noticed that all the black (old neutral) wires were wired together in a terminal block, and the red, blue and yellow wires were connected to the switch. Nothing was taped to indicate what was what.

I understand that it is not very safe to connect the live wires to the switch as it would mean the light is live even when off? It should be the neutrals.

Am I correct to be concerned and if so is it simply a case of wiring all the red wires together and connecting the equivalent black wire to the switch? I'm writing this from memory away from the house but could provide details once at home if required.

Many thanks,

Katie

 

[JohnD]

is the old one a 2-gang switch? or a 2-way switch?

how many terminals does it have?

I understand that it is not very safe to connect the live wires to the switch as it would mean the light is live even when off? It should be the neutrals.

Wrong

 

[EFLImpudence]

I have just changed an old 2-gang light switch dating from about the 70s (I guess) with a modern one. Once inside I noticed that all the black (old neutral) wires were wired together in a terminal block, and the red, blue and yellow wires were connected to the switch. Nothing was taped to indicate what was what.

Ok.

I understand that it is not very safe to connect the live wires to the switch as it would mean the light is live even when off? It should be the neutrals.

Absolute nonsense. Switching the Neutrals would mean the light is always Live.

Am I correct to be concerned

No. You should be concerned about your understanding.

and if so is it simply a case of wiring all the red wires together and connecting the equivalent black wire to the switch? I'm writing this from memory away from the house but could provide details once at home if required.

Being a little kinder, I presume you are thinking of ceiling roses where all the Reds are connected together but even then it is the Live wire which is switched and then the black wire is the Switched Live.

Neutral is not a name for any old black wires.
It is the name for the wire which completes the circuit from the load(light) back to the supply.

 

[katie6]

Thanks for your reply JohnD.

It is a 2 gang switch. The right switch is the only switch controlling an outside light. The left switch is now also the only usedswitch controlling the porch light. The porch switch, although now one way, used to be one of two switches controlling the porch light. However I have removed the other switch (by permanently wiring the other switch to ON and changing it from 3 gang to 2 gang). So now it is the only switch controlling the porch light and I have therefore wired the yellow and blue so that the switches still work (apologies, not home yet!)

It's good to hear that it is not unsafe! Does that mean I have nothing to worry about?

Katie

 

[katie6]

Thanks also EFImpudence. I appreciate your corrections. I don't honestly know what the wiring is in the ceiling rose so sadly don't qualify for your kindness!

 

[JohnD]

Does that mean I have nothing to worry about?

looking forward to seeing some photos.

 

[katie6]

Ok, got some pictures. Hard to see but:

• all the blacks are connected together in one terminal block.
• The yellow and blue from the other switch that used to arecontrol the porch light are now connected together along with a red in a terminal block because there wasn't enough room in the switch for four wires, the fourth being the one that connects the two COM terminals in the switch.
• The two red wires for the right switch control the outside light.

If the image doesn't work, here is the URL:
https://ibb.co/7bX96B8

Many thanks,

Katie

 

[333rocky333]

...

 

[EFLImpudence]

Would you please tell us which of the red wires is in the same cable as the blue and yellow?

 

[katie6]

The red wire in the same cable as yellow and blue is connected to L2 of the left switch. This is the top left terminal shown in the photo.

 

[SUNRAY]

Can you clarify what is at the other end of the red, yellow & blue and double check which red belongs to the 3 core.
Very unscientific but in the picture the red in the connector bloc looks like a better match to the yellow and blue than the red in L2 does.
A pic of the other switch would be helpful.

Assuming the 3 core only goes to the redundant switch and nothing else, it doesn't make any sense when you say the red of the 3 core goes to left swicth.
In my mind this makes more sense but I can't be at all certain without further info about the 3 core:

and IF i'm right the 3 core & E has become redundant and can be removed from the connector.
.

 

[katie6]

Thanks SUNRAY,

I'm at work but will open up the switch again when I get back. An electrician has looked at this in the distant past and couldn't figure out what was going on in this switch! It was baffling as they didn't appear to do anything until I rewired, but getting closer to understanding what wires control what now! From memory, the yellow/blue wire is just connected to the other switch and I have now connected those together in the other switch in such a way that it is the equivalent of being permanently on. I will aim to provide diagrams this evening (if possible as I don't think I have the right to upload images on this forum!)

Appreciate your help.

Katie

 

[EFLImpudence]

Just copy and paste pictures.

 

[katie6]

Hi there,

In response to SUNRAY's question, your diagram is spot on. I've double checked and the blue, yellow and red wires from the same cable are indeed connected together in a terminal block in both this and the other switch I mentioned which does make the cable redundant! I guess this means I can just terminate that cable in the terminal block, and keep the brown wire connecting the COM terminals but disconnect git from the blue/yellow/red?

Also, given the above and everyone's comments so far, can I assume that it is a correct and safe set-up?

Many thanks everyone for your support

Katie

 

[EFLImpudence]

Yes, do as you say and all is well.