Shower switch

[hi1]

Hi, please look at the pics. These are the wires into, right hand, and out of a 50a double pole switch. The cable is 6mm running to a 9.5kW shower. Supplied from a rcd and MCB rated at 40a. The cable was screwed tightly into the receiving hole, that is it wouldn't pull out Thoughts please. This is the third of these switches installed in less than a year, normally pawl inside breaks this one just doesn't operate could it be fried. I took one of the other failed switches apart and could see no signs of internal overheating or arcing. Are the switches carp, I asked for an mk replacement last time, nil stock but we can get one for tomorrow, should have waited. Cheers

 

[ericmark]

I can only guess but it would seem the insulation on the wire was gripped rather than the wire its self causing a poor connection and over heating on the neutral feed, I would seem poor installation methods rather than poor quality switch.

 

[hi1]

Thanks for your swift reply. Does that mean the cable rating for that size shower is o.k?
If I strip the insulation back and trim the copper is it still fit for purpose?

 

[sparkwright]

I would say this is down to a loose terminal.

When you fit these things, I tend to constantly check the tightness of the terminals as I'm fitting it. It seems once you have tightened a terminal, then move the switch unit around, it loosens the terminal a bit.

So when i've connected everything and have offered the switch unit up to back box, I check again everything is tight.

The switches themselves are always rubbish too, even the MK ones are.

The only ones that I can depend on are the round 50 amp Crabtree ones.

They are quite different from the regular squares ones, so you may need some more slack from the cables - but they are good.

Again, double-check the tightness of the terminals before you fit the cover.

 

[Iggifer]

That burnt neutral definitely looks like the screw was down on the insulation, there's no screw mark on the copper and a nice round hole in the pvc that would fit a screw perfectly.

As sparkwright, if you can fit it, get a Crabtree

 

[sparkwright]

On closer inspection it does look quite likely the screw was into the insulation.

 

[amjmfareham]

I think the switch's manufacturer, as seen on the picture, is CED, mainly stocked by Toolstation!

 

[securespark]

To be fair to CED, I used to buy 100's and 100's of their gear from ABM here - http://www.electricals247.co.uk/ - and never had an issue.

The website is not labelled as ABM but their address is ABM in Croydon.

Used to be excellent prices, not sure now.

I used to buy a lot from them, so when I went in the bloke would say "Just tell me what you get this stuff for and I'll beat their prices!"

Top fella!

 

[hi1]

Thanks for taking the time to reply chaps

 

[bubachuba]

Does that mean the cable rating for that size shower is o.k?

that would depend on how the cable has been routed.

 

[ban-all-sheds]

http://www.batt.co.uk/upload/files/4d5.pdf

 

[Adam_151]

I would say this is down to a loose terminal.

When you fit these things, I tend to constantly check the tightness of the terminals as I'm fitting it. It seems once you have tightened a terminal, then move the switch unit around, it loosens the terminal a bit.

So when i've connected everything and have offered the switch unit up to back box, I check again everything is tight.

While I don't do a lot of shower switches, I have not known one I have fitted to burn out.

I firmly believe that if you pick a half decent brand, take care when second fixing it and are not limp wristed. That you are not likely to have it fail

 

[ban-all-sheds]

I've only done 1.

About 12 years ago.

It's not burnt out yet.