DIY Doctor

Shower power problem

Postby xyu » Mon Jan 25, 2010 12:51 pm


My electric shower switched itself off while I was using it. I pressed the button on the fuse and it came back on, but the next day it went back off again, so I'm guessing there's a fault with the shower which is causing it to trip. Is there any point in me getting an electrician out to have a look first, or should I just go ahead and replace the shower?

This shower requires you to flick one of those red switches on the wall out in the hall, to switch the shower's power on. I've removed the casing for this switch, and opened up the shower's control unit, just to have a look inside; can't see any visible signs of damage.

One other thing: my flat has one of those old-style fuse-wire fuse boxes. Actually, the fuse for the shower is the only fuse I have which is a push-button style one. The others are all wire fuses.

Thanks for any advice!

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Postby sparx » Mon Jan 25, 2010 8:48 pm


from your description it would seem you have on old style 'Wylex' consumer unit with rewireable fuses which had an early type of Miniature Circuit Breaker fitted to run the shower.
The push button type are quite old having been superceded by a later version which have a lever type switch as most modern MCB's have.
It may be that the shower is on or over the rating of the mcb which has had enough of life!
The easiest/cheapest option would to be to get a replacement from a B&Q store who sell them for around £9, this is a straight forward swop not requiring the consumer unit cover to be removed, just turn off the main switch whilst doing so.
Take note of the current rating of the old one in Amps & get the same.
I assume the shower has not been changed for a larger than original one!
If the new MCB also trips off then you can reckon on a new shower.
One must assume there is also an RCD fitted to the supply, either before the consumer unit or in the shower circuit somewhere? if not then I would urge you to seek help from an approved electrician to advise,
regards Sparx
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Postby ericmark » Mon Jan 25, 2010 8:52 pm

Any other forum and you would get pictures of a crystal ball but lack of pictures is one of the draw backs here. The first question is what is that “Button” I will guess reset on old Wylex consumer unit? If so there are two possible faults.
1) Shower drawing too much.
2) MCB faulty.
On Screwfix web site a WYLEX 40A SP Type B Curve MCB costs £9.19 and simply plugs in so I would think that would be worth the £9.19 to try. (Likely cheaper in local whole sale outlet)

With clamp on ammeter an electrician could quickly work out what is wrong. And if not the MCB you have wasted £9.19 but also if no RCD is fitted I am sure any electrician worth his salt will want to add one.

This of cause is the question. How much do you think the lives of people using shower are worth. Nothing in your post refers to an RCD and today no one would dream of installing a shower without RCD protection. Years ago we did all sorts which would not be permitted today. On opening of M1 busses were designed (two front axles) to travel at 100 MPH for service to Scotland but these are now in history books. The same with Electrics many ideas of yesteryear are no longer permitted.

So do you go for cheap option or do you play safe? Your call!

I fitted RCD’s to all circuits in my house back in 1991 as I felt I would never forgive myself if my children were injured (Wife is expendable). And when my children were growing up they did trip the devices. My son taking up Amateur Radio as a hobby did not help.

So over to you. What will you do?
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Postby xyu » Mon Jan 25, 2010 9:22 pm

Thanks Sparx.
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