Shower using too much juice..

Mar 21, 2007 4 Replies
T

My plumber fitted a new (very nice) shower that requires a 40 amp supply onto the existing wiring which is 30 amp, after 10 minutes under the shower it will cut out as the fuse trips (and is v.hot). I like the new shower and don't want a less powerful one. It is on 6 mm cabling and is directly connected through a wlex box that has 30 amp written on it. What I want to know is if I buy a replacement fuse for this box that is rated 40 amp will it work as required. I've seen these

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M

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What about the cabling? According to this website

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table A1 about 2/3 down the page you need 10mm^2 cabling for a 40 amp supply. You really need to rewire with the larger cable to avoid the possibility of a fire. Replacing the fuse increases the danger. Ok replacing the fuse by a MCB changes things slightly as it will blow sooner than a piece of fuse wire.

I may be wrong but I reckon your plumber has bodged the job and put your life in danger. But I could be wrong and I hope I am. But please get it checked by a competant electrician before you do anything as rash as change the fuse.

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A

Actually, you're right. The fuse is doing its job and saving you from a fire. However repeatedly abusing the fuse may itself result in a fire. You should have stopped using it the first or second time it blew.

In some limited circumstances, the cable could be OK. You need to get it checked by an electrician, who can advise if the cable needs replacing, or if it's OK just to replace the fuse. He also needs to check the earth bonding is up to spec, and the earth fault loop impedance is OK with the fuse being used. It doesn't sound like the plumber was electrically competent, and his work needs checking and correcting.

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F

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6mm is OK for 42A if surface wired. If its not buried in plaster it should be OK right?

Legaly I think because of Part P the plumber shouldn't have wired it up because its in a bathroom.

If its a 9.5KW shower then it should be on 10mm cable , if its an

8.5KW shower it should be OK on 6mm, but because of the OPs inexperience he should get an electrician to confirm.
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P

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IIUC, the advice to fit 10 mil is quite recent and many

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