Fitting A Shower Pull Switch

[Aquaman]

Hi,
I am replacing a shower pull cord switch as the original has broken.
Can anyone help with a few questions.

1.The new one is an MK and says 50 Amp, when I opened the old one it has 45Amp written in it, does this make a difference.

2.I was just going to copy the wiring from the old one, but they have different markings. The Old says In & Out on the terminals and the new says Load & Supply.....can anyone tell me how to wire (i.e does In=Supply?)

3. And lastly there is only one earth terminal on the new one, the old has separate terminals for the earth wires. Do both earth wires go in the same earth terminal in the new one?

Why is nothing easy!
Thanks in Advance for any answers.

 

[DetlefSchmitz]

1.The new one is an MK and says 50 Amp, when I opened the old one it has 45Amp written in it, does this make a difference.

50A is 'better' than 45A - so it's OK.

2.I was just going to copy the wiring from the old one, but they have different markings. The Old says In & Out on the terminals and the new says Load & Supply.....can anyone tell me how to wire (i.e does In=Supply?)

Yes it does.

3. And lastly there is only one earth terminal on the new one, the old has separate terminals for the earth wires. Do both earth wires go in the same earth terminal in the new one?

Yes.

 

[bernardgreen]

If the leads show any sign of having been hot then providing there is enough slack in the cables cut of the ends.

Signs to look for are melted or deformed insulation and / or discolouring of the terminal in the old switch.

Heat softens the copper and the new switch is then likely to fail sooner than it should if the softened copper does not make a good electrical contact with the terminal as this will become hot.

 

[Aquaman]

Thank you both for your speedy replies.

It is only the pull switch that has stopped working (was always very clunky) the wiring looks fine, but thanks for the tip Bernard

 

[Aquaman]

Upon further inspection of the live/supply wire it does show some heat damage with deformed insulation and discolouring of the terminal.

Is this OK, seems a bit unusual?

The shower and it's RCD and MCB were fitted professionally within the last 2 years.

 

[Taylortwocities]

The shower and it's RCD and MCB were fitted professionally within the last 2 years.

Not very professionally if the wiring is discoloured. That is a sign that the terminations were not properly done.

Cut the conductors back to bright copper. Use a screwdriver of teh correct size for the screws and make sure they are good and tight. If they are not tight then the high currents will cause the connections to heat up - this will jigger the terminations, the cable and the switch.

PS - to the experts on this forum. "Jigger" is a recognised BS7671 definition

 

[DetlefSchmitz]

Is this OK, seems a bit unusual?

I suspect not that unusual. It may just not have been tightened up enough originally. Bad connections heat up and this heat degrades the connection still further.

Bernard had it right - try and do as he said when replacing the switch.

EDIT: Oh well...

 

[ban-all-sheds]

Is this OK, seems a bit unusual?

No to both of those, sadly.

 

[bernardgreen]

Not very professionally if the wiring is discoloured. That is a sign that the terminations were not properly done.

Might have been done properly. One cause of premature failure of a shower switch is people leaving the shower switch on and using the pull cord as a more convenient way to turn the shower on and off.

Some of them seem unable to do more than a few hundred operations under load before the contacts start to fail and over heat when ON.

That is the subtle difference between an isolator and a switch. Switches are designed to switch the load on and off frequently. Isolators are designed to isolate it only occasionally when on load.

 

[Aquaman]

Not very professionally if the wiring is discoloured. That is a sign that the terminations were not properly done.

I have fitted an MK switch so hopefully thats a good quality?

Just to save me worrying.....Am I right in thinking that if the switch or wires did get too hot it would trip the MCB....before a fire

 

[DetlefSchmitz]

Just to save me worrying.....Am I right in thinking that if the switch or wires did get too hot it would trip the MCB....before a fire

No I'm afraid it wouldn't. It's important to do a good job.

 

[Aquaman]

Just to save me worrying.....Am I right in thinking that if the switch or wires did get too hot it would trip the MCB....before a fire

No I'm afraid it wouldn't. It's important to do a good job.

Well I trimmed back the one heat damaged wire to clean copper and made sure all the connections are tight....so it should be all OK.
Thanks again for your help.

 

[DetlefSchmitz]

You could always take a look at it in a week's time and check it still looks ok - even check the tightness.

It's one of the advantages of DIY.