Just wondering

Wife's friend asked me to look at her shower today. Light was on at the pull cord switch but shower weren't working. Anyhow I've got my volt tester, which I originally purchased to curtail the number of shocks I used to get around anything electrical, and tested for current at the shower. Nothing there. Tested at pull cord switch and got a faint flicker. Under the stairs there is a seperate switch unit with a re-wireable 45 amp fuse. I removed the fuse and tested across the contacts and got another faint flicker on my tester. Further investigation revealed 240 volt going into the switch. I've told her that the switch unit appears to be broken and she needs a spark to sort her out with a new RCD unit. I was just wondering it it is usual for these switches to fail in this way. I've come across it on the pull cord type before but never on these.

It is not all that unusual for a shower switch to fail if it has not been made off properly.
Showers use alot of power, so if there is a loose conection at the switch it will arc and burn out.

Was there any sign of burning at the back of the shower switch?
Did you / could you test for continuity on both the live and neutral side of the shower switch?

I personally think its about time the design of 45A DP switches were changed to better accomodate the larger size of cables being used by modern showers. 10mm T & E is very chunky cable and to have 2 going into a plastic (brittle ) box can be tricky and it is this that causes problems. Of course if you are careful you can do it but it is about time a more robust box was manufactured.

http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=A431904&ts=43015&id=90597

The switch fastens to the ceiling and a cover fits over it, rather than the more usual alternative where you fit a box to the ceiling and mount a switch on it like you'd mount any accessory. Means terminating the conductors is easier because its less of a confined space, and unlike normal switches, screwing the lid on is a doddle because you haven't got to fight big conductors into the box.

Hi guys. Thanks for the replies. I think I possibly did not make myself clear. It wasn't the pull-cord switch that I suspected had failed, I've seen a couple of these myself, but the main isolator under the stairs with a re-wireable 45amp fuse. Although it's out of my hands now, I was just wondering if these units were prone to failure. This one is only five years old and my parents have had one in for about thirty years. I suppose nothing lasts forever.

flemsbog said:

Hi guys. Thanks for the replies. I think I possibly did not make myself clear. It wasn't the pull-cord switch that I suspected had failed, I've seen a couple of these myself, but the main isolator under the stairs with a re-wireable 45amp fuse. Although it's out of my hands now, I was just wondering if these units were prone to failure. This one is only five years old and my parents have had one in for about thirty years. I suppose nothing lasts forever.

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Its pretty rare, as they are often rated well over the power they will be switching, and they are virtually never used, especially not under load conditions.

But it is not impossible that it is this that has failed, especially if it was not made off properly to start with.

Could it be the weather? I had one of these on Saturday. 240 volts on the tails from a henley block into the switch, but pulled the fuse and was only getting 110 volts across the contacts. Not my area of expertise so left name of a leccy and left.