Shower switch wiring

Joined
13 Apr 2012
Messages
358
Reaction score
2
Location
Durham
Country
United Kingdom
I need to replace my shower switch pattress box so took the old one down and have a query regarding earths. As expected, there's the 3 core cable into the switch and the 3 core cable out but there are also 2 further earth wires. I've been in the loft to check and the earth wired to the IN/SUPPLY goes off to a cold supply pipe. The other earth wasn't connected to anything in the switch (It may have been ripped out at some point by accident, perhaps when the loft insulation was fitted) I've looked in the loft and it leads to a ceiling light.

So what to do with this spare earth? I've looked at a wiring diagram and it seems the IN needs an earth (which it has, from the cold pipe) but doesn't seem to say that the OUT/LOAD needs one as well, so I'm confused. Should I secure the loose earth to the OUT/LOAD?
 
Last edited:
Sponsored Links
Thanks, so you're saying fit the earth that's currently loose to the LOAD side earth, and leave the earth that goes to the cold pipe to the earth on the SUPPLY side?

I have now taken the switch down and found that one of the live wires is burning out. What is a good replacement switch? I believe I need one with double screws? It is connected to a 40A MCB.
 
Sponsored Links
Connect them both to earth with the cable earths.
Sorry for the confusion I'm just still trying to understand what you mean by this.

Obviously the SUPPLY on the switch has an earth terminal and the LOAD has an earth terminal. Are you saying connect one of these supplemental earths to the supply side and the other to the load side - in other words in the same terminals as the earths from the 3 core cables?
 
Connect all four earths together.

There may be two earth terminals on the switch but these are connected together by a metal strip so it doesn't matter which of the four wires you put in which of the two earth terminals.
 
It's going to have to be a square one as that's what I've got now. I'm unsure on the make but as it's burning out I need a new one pronto.

Is it essential/recommended to get one with the two screws per terminal?

And should it be 45A or 50A? The MCB on the shower circuit is 40A
 
Last edited:
as it's burning out I need a new one pronto.
You will also need to cut back the cable to before any burnt/discoloured parts - not only does the insulation become brittle when it overheats like that, but the copper core hardens, and then it won't make good contact with the terminals on the new switch, so you get overheating, and the whole cycle starts again.


Is it essential/recommended to get one with the two screws per terminal?
They lessen the chances of not getting a good connection.


And should it be 45A or 50A? The MCB on the shower circuit is 40A
What's the rating of the shower?
 
You need to establish why that live is "burning out" is it arcing due to a loose connection or something else? Putting a new bb and switch in will not solve your wiring issue unless its a loose connection at the switch terminals that you are replacing. Do you have RCD protection on that circuit? Is the MCB actually functioning as it should, does the cpc provide a path to earth (in other words is it actually physically connected to the cu in continuity) You need to research, inspect and investigate these situations before just buying a new switch or it might just be good money after bad.
 
Putting a new bb and switch in will not solve your wiring issue unless its a loose connection at the switch terminals that you are replacing. Do you have RCD protection on that circuit?
How could that be relevant to a conductor overheating at the switch?


Is the MCB actually functioning as it should,
How could that be relevant to a conductor overheating at the switch?

How could he test it anyway?


does the cpc provide a path to earth
How could that be relevant to a conductor overheating at the switch?
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Back
Top