Shower switch - feed/load question

[ILikeFish]

Hi All,

I have a pull-cord shower switch that's blown, and am looking to replace it. When I opened it up, the old switch has "in" and "out" terminals (which I assume correspond to "feed" and "load"?).

What I don't understand, is that the neutral wires for in and out are crossed; ie. the mains live goes to the "in" L terminal, but the mains neutral goes to the "out" N terminal.

My question is, why is it wired like this? I would have expected both feed-side wires to go to the "in" terminals.

Thanks for any help, I'm curious...

Regards
Jon

 

[electronicsuk]

Sounds like whoever wired it in made a mistake, both the live and neutral of the supply cable should go to the in/feed side of the switch.

 

[333rocky333]

It is essential the supply cables both go on the in side.

Although it was still switching both poles , and the indicator light , if you had one, was going on and off.

The shower was possibly never fully isolated , due to the Live shower cable still connected to the incoming neutral conducter via the indicator light, when the switch was off.

 

[ILikeFish]

Thanks all - I will wire up the new switch as per the instructions.

What bothers me is that it wouldn't have been a simple job to get the neutrals mixed; whoever installed the switch obviously went to some effort to do just that, and I don't know why...

The only problem I can see is that I can't be certain which of the cables coming out of the ceiling should be the feed side, and which should be the load side. I certainly don't want to just rely on the existing wiring as a guide, for obvious reasons.

So, if I happened to attach the feed side to the load terminals, and vice-versa, what would happen? I don't know how these switches work internally - would I see the neon not switching off?

Thanks again,
Jon

 

[333rocky333]

The pairs as you know should be in the same cable, if the in and out were reversed on the switch the indicater would be on, in both switch positions.

It is possible the previous bloke never knew either and the light at first stayed on, he then proberly swopped the lives , see the light now working and thought that was is it and just left the neutrals as they were.

 

[ban-all-sheds]

When I opened it up, the old switch has "in" and "out" terminals (which I assume correspond to "feed" and "load"?).

Yup.

My question is, why is it wired like this? I would have expected both feed-side wires to go to the "in" terminals.

It doesn't really matter - it's a DP switch so it will still isolate both poles, the only downside of getting live supply & load reversed is that the neon will be on all the time.

It may have been easier given how the cables arranged themselves - if they're 10mm² you'll find they aren't very cooperative.

Or it could have been that the person who originally installed it first wired it with the supply across one pair of in/out terminals (yes, some people are that dim) and didn't swap everything over when he fixed it.

 

[333rocky333]

My question is, why is it wired like this? I would have expected both feed-side wires to go to the "in" terminals.

It doesn't really matter - it's a DP switch so it will still isolate both poles.

How I see it,
The switchline would become in series with the neon that is connected to the supply neutral,
I would not count both poles as isolated.

 

[ban-all-sheds]

Yes - you're right - it would be in series with the neon.

Sorry.