Shower Cable
- Thread starter motor
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this seems to happen quite often, perhaps because the load on a shower switch is so high.
Sadly the wire has become slightly loose it its terminal. This causes it to overheat. the hotter it gets, the looser it becomes, and so it overheats more.
You are going to need a new shower switch. The wire that has overheated has been damaged, so it needs to be cut back to a part that is not discoloured. this might mean that it is necessary to crimp on an extra length of wire, if there is no slack.
Screw connections should be checked for tightness, and re-tightened, an hour or so after fixing, and again after a few days. It seems that the soft copper wire changes shape under pressure of the screw so that the grip loses its tightness. Once a connection has come loose and overheated you will never be able to make it form a good permanent joint, it will come loose again. Hence the new switch and undamaged wire is needed for the new connection.
I have heard it said that the switch is more likely to suffer if the shower is "on" when the pull-cord switch is operated.
Sadly the wire has become slightly loose it its terminal. This causes it to overheat. the hotter it gets, the looser it becomes, and so it overheats more.
You are going to need a new shower switch. The wire that has overheated has been damaged, so it needs to be cut back to a part that is not discoloured. this might mean that it is necessary to crimp on an extra length of wire, if there is no slack.
Screw connections should be checked for tightness, and re-tightened, an hour or so after fixing, and again after a few days. It seems that the soft copper wire changes shape under pressure of the screw so that the grip loses its tightness. Once a connection has come loose and overheated you will never be able to make it form a good permanent joint, it will come loose again. Hence the new switch and undamaged wire is needed for the new connection.
I have heard it said that the switch is more likely to suffer if the shower is "on" when the pull-cord switch is operated.
Why`s it always the neutral?
I've heard people say that it is due to the original fitter treating N as less important than P, but I don't believe it.
I also don't believe it can be caused by electrolytic migration, because on an AC supply, polarity changes 50 times a second.
I'm prepared to believe it might be something to do with the nearby presence of an earth at nearly the same potential.
I'd even be ready to listen to any evidence that it was the chemical composition of the black-coloured PVC insulation.
Never seen any convincing explanation though.
I also don't believe it can be caused by electrolytic migration, because on an AC supply, polarity changes 50 times a second.
I'm prepared to believe it might be something to do with the nearby presence of an earth at nearly the same potential.
I'd even be ready to listen to any evidence that it was the chemical composition of the black-coloured PVC insulation.
Never seen any convincing explanation though.
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JohnD said:
John, you can tighten something up too much, you know!
What you DON'T want to do is crush to conductor...
A 30 Amp cable?
At 230V that's a tad less than 7 kW. What rating shower is connected to this switch?
At 230V that's a tad less than 7 kW. What rating shower is connected to this switch?
Lets open a book on the size of the shower. I reckon he'll come back and say 8.5KW.
Any other takers?
Any other takers?
30 amp cable? i sincerely hope he doesn't mean 4mm², or god forbid, 2.5mm².
For motor (the OP), here are some approx. optimum cable ratings. (DO NOT take these as gospel, they are off the top of my head)
1mm² 10A
1.5mm² 16A
2.5mm² 27A
4mm² 36?A
6mm² 40A (shower no more than 9kw)
10mm² 60A (for any shower more than 9kw - most shower circuits run in this nowadays)
HOWEVER, it is incorrect to say "I have used 40A cable", since 6mm² is rated at 40A ONLY when it is run on the surface, in free space. If it is run in insulation, it MUST be derated, because the cable gets warmer in insulation, and will melt if run at its optimum capacity.
In general, most shower circuits these days are being run in 10mm² cable, so if you need to replace the cable, use this, as it will be future proof then. And you could have that 10.8kw shower you've always wanted. NOTHING below 6mm² should ever be used to wire a shower.
For motor (the OP), here are some approx. optimum cable ratings. (DO NOT take these as gospel, they are off the top of my head)
1mm² 10A
1.5mm² 16A
2.5mm² 27A
4mm² 36?A
6mm² 40A (shower no more than 9kw)
10mm² 60A (for any shower more than 9kw - most shower circuits run in this nowadays)
HOWEVER, it is incorrect to say "I have used 40A cable", since 6mm² is rated at 40A ONLY when it is run on the surface, in free space. If it is run in insulation, it MUST be derated, because the cable gets warmer in insulation, and will melt if run at its optimum capacity.
In general, most shower circuits these days are being run in 10mm² cable, so if you need to replace the cable, use this, as it will be future proof then. And you could have that 10.8kw shower you've always wanted. NOTHING below 6mm² should ever be used to wire a shower.
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