Fan isolation switch configuration error

[sweetpea]

Hello Guys I am new to the forum

I was looking for a little advise if possible. My bathroom fan isolation switch has cracked & was looking to get it replaced. I isolated the supply and inspected it. As it looked very simple to replace I purchased a new switch. The new switch arrived but it has a different configuration on the back to the old one.

The old configuration on the top row (off) from left to right is L1, L2, N,
The bottom row (on) mirrors the top row L1, L2, N,

The new switches rear configuration looks very different & does not mirror one another

The top row (off) has four terminals (L2 blanked) Lcom, L1, (L2 No screw), Lcom
The bottom (on) four terminals (L2 blanked) L1, (L2 No screw), Lcom, L1

I seem to have 3 x Lcom's (2 on the top row & 1 on the bottom row)
3 x L1's (1 on the top row & 2 on the bottom row)
with no L2's as they have no access to them & are blanked off.

Can anyone advise as to which wire goes to which terminal?
It is 4 core cable Live (brown), switched live (black), Neutral (grey) & earth (terminal block)

Many thanks

 

[davesparks]

It sounds like you have got a very cheaply made switch, they have used the workings and backshell of a 3 gang switch, removed the unused L2 screws and just put a different front on it.

There should be some markings to indicate which com connects to which L1, but they normally go in order.

So starting from on side of the switch the first com at the top switches to the first L1 at the bottom, the L1 at the top in the middle switches to the com in the middle at the bottom and the second com at the top switches to the second L1 at the bottom.

Match the order of the connections as they are on your existing switch and it will work.

So for the top row reading from the left connect L, SL then N
Then on the bottom row repeat this order again starting from the left L, SL, N

If the new switch is metal then you must connect an earth to it.

 

[sweetpea]

It sounds like you have got a very cheaply made switch, they have used the workings and backshell of a 3 gang switch, removed the unused L2 screws and just put a different front on it.

There should be some markings to indicate which com connects to which L1, but they normally go in order.

So starting from on side of the switch the first com at the top switches to the first L1 at the bottom, the L1 at the top in the middle switches to the com in the middle at the bottom and the second com at the top switches to the second L1 at the bottom.

Match the order of the connections as they are on your existing switch and it will work.

So for the top row reading from the left connect L, SL then N
Then on the bottom row repeat this order again starting from the left L, SL, N

If the new switch is metal then you must connect an earth to it.

Thank you Dave for your advise it's greatly appreciated.
Now it make sense. I will let you know how I get on tomorrow once I'm back home.
I did buy the switch from an electrical wholesaler so I probably will return it.
It's a plastic switch in plasterboard wall.
Best regards

 

[pc1966]

Out of curiosity, do you know what make/model you got?

The most recent one I bought was, I think, one of these:

https://www.NoLinkingToThis/p/briti...solator-switch-white-with-white-inserts/69862

It was easy to get and actually labelled as "fan isolator" so others would know its purpose in life!
[automerge]1589052992[/automerge]
On second thoughts it was rounded edge, so maybe this one:

https://www.NoLinkingToThis/p/briti...solator-switch-white-with-white-inserts/928ht

 

[sweetpea]

Thank you PC1966 for your advise. Funny enough after reading Dave's comments I went online & purchased the exact same model from screwfix. Though I had to buy the square edged version as the slimmer profile was out of stock for collection today.
Thank you again
Best regards

 

[pc1966]

Hopefully that is now a quick and easy fix!

The wiring is straightforward just as you originally identified, typically with the earth joint as part of the back box.