UK Shower switches burning

[Bob Geldoff1234]

I have just been called out to another burning shower switch.Upon removal the wires had been burnt and chared.One thing I've noticed on all burnt shower switches is that the stranded wires haven't been twisted and just put in straight.I always twist the standed cables to make one solid conductor before inserting into the terminal.My thoughts are that the screw only clamps a few strands when they are straight,leaving the other stands either side of the screw.With the load on a shower I feel this is a weak point and hence why they burn out.Obviously it can also be caused by loose terminals but back in the day when shower switches had two screws per terminal,I don't recall having to replace that many switches.Prehaps they should bring back the two screw method?

 

[brianmoooore]

100% agree on the two screws, but equally as much disagree on the twisting. If a clamped, twisted cable is turned in the direction that untwists the strands, some of those strands can move up into the voids either side of the screw threads, leaving the remaining strands under the screw head insecure.
The correct method, IMHO, is to leave the strands straight and tighten the screw(s) while gently twisting and untwisting the cable, so that some of the strands completely fill the voids. This assumes a correctly designed fitting, where the diameter of the screw is a good proportion of the diameter of the tunnel for the cable, and that the diameter of the tunnel isn't massively greater than the cable.

 

[nicebutdim]

With coarse stranded cables in screw terminals, I also tend to tighten, manipulate the cable and re-tighten. This process may be repeated two or three times until it's clear the cable is bedded nicely in the terminal and unlikely to loosen through thermal creep.

 

[oscar21]

The shower switches and pull cords I find burnt out are the ones where the customer operates them every time they have a shower.

 

[Mikegh]

The shower switches and pull cords I find burnt out are the ones where the customer operates them every time they have a shower.

There's a lot that control the shower via pullcord for convenience

I wouldn't twist coarse stranded

 

[MDJ]

I have just been called out to another burning shower switch.Upon removal the wires had been burnt and chared.One thing I've noticed on all burnt shower switches is that the stranded wires haven't been twisted and just put in straight.I always twist the standed cables to make one solid conductor before inserting into the terminal.My thoughts are that the screw only clamps a few strands when they are straight,leaving the other stands either side of the screw.With the load on a shower I feel this is a weak point and hence why they burn out.Obviously it can also be caused by loose terminals but back in the day when shower switches had two screws per terminal,I don't recall having to replace that many switches.Prehaps they should bring back the two screw method?

I have also seen this many many times, IME it is due to loose connections and cheap switches.

 

[mainline]

I have just been called out to another burning shower switch.Upon removal the wires had been burnt and chared.One thing I've noticed on all burnt shower switches is that the stranded wires haven't been twisted and just put in straight.I always twist the standed cables to make one solid conductor before inserting into the terminal.My thoughts are that the screw only clamps a few strands when they are straight,leaving the other stands either side of the screw.With the load on a shower I feel this is a weak point and hence why they burn out.Obviously it can also be caused by loose terminals but back in the day when shower switches had two screws per terminal,I don't recall having to replace that many switches.Prehaps they should bring back the two screw method?

Replace with one of these.

Click Essentials Polar 50 A Double Pull Cord Switch with Mechanical On Or Off and Neon Twin Terminal Screws PRW211

The Click PRW211 Polar White 50A double pole flush mounting square pullcord ceiling switch is ideal for isolating modern electric showers. With its bright white finish it adds a quality finish in today's bathrooms.

www.cityplumbing.co.uk

 

[nicebutdim]

Replace with one of these.

Click Essentials Polar 50 A Double Pull Cord Switch with Mechanical On Or Off and Neon Twin Terminal Screws PRW211

The Click PRW211 Polar White 50A double pole flush mounting square pullcord ceiling switch is ideal for isolating modern electric showers. With its bright white finish it adds a quality finish in today's bathrooms.

www.cityplumbing.co.uk

Better to use one of these

Click Polar 50A DP Pullcord Switch Round PRW213 | Click4Electrics

Buy your Click Polar 50A DP Pullcord Switch Round PRW213 from Click4Electrics today. Free delivery on orders over £75. Shop now!

www.click4electrics.co.uk

 

[mainline]

Better to use one of these

Click Polar 50A DP Pullcord Switch Round PRW213 | Click4Electrics

Buy your Click Polar 50A DP Pullcord Switch Round PRW213 from Click4Electrics today. Free delivery on orders over £75. Shop now!

www.click4electrics.co.uk

Yes that's the ones, I think we have been here before when I mentioned the Crabtree.

 

[Rockingit]

Whilst agreeing with comments above, I’ve always thought that the single largest challenge in installing these (of any type, though 100% recommend the new Click/Crabtree style) is simply that they’re a pain in the neck to fit because you’re working overhead, usually close to a wall on one side, with a tiny amount of slack on a big stiff cable. And, what gets me is that there’s not even an actual need for them in the first place!!

 

[nicebutdim]

Whilst agreeing with comments above, I’ve always thought that the single largest challenge in installing these (of any type, though 100% recommend the new Click/Crabtree style) is simply that they’re a pain in the neck to fit because you’re working overhead, usually close to a wall on one side, with a tiny amount of slack on a big stiff cable. And, what gets me is that there’s not even an actual need for them in the first place!!

While I like the round switches, their weakness (Crabtree at least as I've not used Click) is terminal placement means fixing one cable before the base if located anywhere close to a corner.

 

[oscar21]

Those round Crabtree ones are so near yet so far from being the perfect shower pull cord. The way the wire

While I like the round switches, their weakness (Crabtree at least as I've not used Click) is terminal placement means fixing one cable before the base if located anywhere close to a corner.

Yes, they've angled the terminal screws so if you put it in a corner then three screws are facing a wall, you have to wire it all up before you fix it to the ceiling.

 

[Pete999]

Yes that's the ones, I think we have been here before when I mentioned the Crabtree.

loose connection somewhere

 

[MDJ]

Whilst agreeing with comments above, I’ve always thought that the single largest challenge in installing these (of any type, though 100% recommend the new Click/Crabtree style) is simply that they’re a pain in the neck to fit because you’re working overhead, usually close to a wall on one side, with a tiny amount of slack on a big stiff cable. And, what gets me is that there’s not even an actual need for them in the first place!!

yep I get your point, I hate them, my shower at the moment is off the combi boiler, but when I did have electric I had a 45 amp double pole switch on a deep twin patterice in an airing cupboard, so much room in it compaired to the pull switches fitted today

 

[Taylortwocities]

Has anyone worked out why it is more often the neutral rather than the line connection that fries?

 

[nicebutdim]

Has anyone worked out why it is more often the neutral rather than the line connection that fries?

That's a question I'd love to see answered with something better than speculation.

 

[Rockingit]

That's a question I'd love to see answered with something better than speculation.

The ‘theory’ that I’ve always heard touted around on this is that (think Fleming’s rules…) the direction of current in the neutral encourages the screws to loosen. My gut has always told me to claim BS on that whilst my head has always told me to find more facts either way…

 

[brianmoooore]

The ‘theory’ that I’ve always heard touted around on this is that (think Fleming’s rules…) the direction of current in the neutral encourages the screws to loosen. My gut has always told me to claim BS on that whilst my head has always told me to find more facts either way…

I think that the fact that the direction of current flow in the neutral is identical to that of the live, just 1/100th of a second later, rather disproves this theory.

 

[Taylortwocities]

I think that the fact that the direction of current flow in the neutral is identical to that of the live, just 1/100th of a second later, rather disproves this theory.

Indeed, Kirchhoff's Laws IIRC!

 

[mainline]

Has anyone worked out why it is more often the neutral rather than the line connection that fries?

Maybe because more attention is given to tightening the L conductor.