2 Gang switch in Garage - wiring seems strange

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Chris Farmer

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Hi, the above image is the currently connected state of a 2 Gang switch which I believe was part of the old house alarm that has never worked and mostly been taken out. I was assuming that these two switches powered the internal PIRs, outside alarm boxes and an outside PIR.

I was hoping to use one of these switches for an outside light in place of the old outside PIR which I disconnected (live, neutral, earth). I tested power to these wires and found that there was a 240V no matter what the switching arrangement of the 2 gang switch although there is no power when the fuse is pulled, so I'm deducing power is coming from this circuit however I can't understand why the switches make no difference to the voltage test. I used an analog multimeter to test the AC voltage between the live and neutral, should I have tested between the live and earth?

I also can't understand the existing wiring of the 2 gang, I would have assumed that the main feed coming from the fuse box would have been connected to either of the coms. It doesn't seem to match either a one-way or two-way. Obviously a one-way switch would be best.

Any helpful insight would be greatly appreciated.
 
If it’s all redundant, just rip if all out and start again. but, As a first step, if you have no power (between L&N) then you need to discover why.
 
There is only no power when the fuse is pulled, when the fuse is in there is always power between live and neutral no matter if the switches are down or up or opposite to each other?
 
Sorry if I haven't made it clear, I was testing the red and blue that comes out of the wall in the back garden. Before I made the diagram of the current switch in the garage I disconnected the outside PIR to give a Red Blue and Earth coming out the wall. I then tested the red and blue against all the different combinations of the switch in the garage. The red and blue coming out the wall are live not matter what I did with the switches n the garage. However if I removed the fuse from the fuse box the was no voltage to the wires from the wall outside.

After this I removed the switch plate and made a diagram of the switch connections which are as far as I have got. I can't understand why when the fuse is replaced there is always power no matter if the switches are up or down and I don't know why the main feed from the fuse box is connected to L1

Testing all connections in the switch these is no power when the fuse is out hence the main feed must be coming from the fuse box.
 
Your diagram shows the red from the 13A connected directly to the red of the light. It’s not been switched as it’s in the same terminal
 
OK so basically whoever connected this up just used the 2 gang to make a permanent live connection to both circuits, as it stands the actual switches are irrelevant? is this correct?
 
Chris Farmer said:
permanent live connection to both circuits, as it stands the actual switches are irrelevant? is this correct?
Click to expand...

No, the right switch does switch something on and off, but only when the left switch is in a certain position.

It would make a lot more sense if the incoming red wire from below went to either of the COMs and that the PIR had an override. I really hope the yellow wire is not being used as the earth, so don't move the red wire into a COM until you've sorted out the PIR end and sorted out or disconnected the other cable too.

edit: when I say left and right switch, I mean as per the hand drawn diagram, not when the switch is screwed to the back box.
 
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Let's start again.
What do you want to do?
Don't try to predict or analyse.

Just tell us what you want to achieve.

AND is there an earth wire in the red,yellow,blue? it is likely to be in the green and yellow sleeve with the other twin and earth cable.
 
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rsgaz - OK thanks for your help,

I was hoping to connect an outdoor light in place of the old PIR which I could then turn on and off with one of these switches (a one-way switch). The other switch is irrelevant and will not be used.

The yellow wire is not being used as an earth (currently connected to L2) I assumed this to be a switched live?
Since I tried all combinations of the switches and tested the on the old PIR cables I think I can confirm that the right switch (hand drawn diagram) does not turn the old PIR circuit on and off.
 
Does you PIR fitting have an overide facility?

Assuming it does the following is the way to go.
This will give a permanent live for the PIR feed on the red,
Neutrla on blue.
Overide [or may be called switched or switched live] on yellow and
Earth on green/yellow.

Check this circuit is on an RCD.
Don't forget to change the fuse to 3A or 5A

upload_2020-8-8_21-18-52.png

Removing the link between COMs disconnects the other cable. Actually i suggest 'parking it in L2 as shown so it's there for future use.
Additionally I suggest removing the unused black wire from the joint and putting it in with the earths.
 
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