Shower using too much juice..


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 http://www.tlc-direct.co.uk/Products/WYC30.html http://www.screwfix.com/app/sfd/cat/pro.jsp ;jsessionid=GML25IBFHCRMECSTHZOCFEY?idw992&slotName=null&homeRef=&cm_re=CROSS_SELL-_-SLOT1-_-77992&catId=PRODUCT_DETAILS&tsr363&destination=/app/sfd/cat/pro.jsp%3Fid%3D77992%26slotName%3Dnull%26homeRef%3D and think that it would fit, do you guys think this will be safe? This would mean the white box would remain (that has 30 amp written on it, but there would be a new fuse/mcp of 40 amp in it so that would be okay?? Cheers Matt OC
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snipped-for-privacy@gmail.com wrote:

http://www.screwfix.com/app/sfd/cat/pro.jsp ;jsessionid=GML25IBFHCRMECSTHZOCFEY?idw992&slotName=null&homeRef=&cm_re=CROSS_SELL-_-SLOT1-_-77992&catId=PRODUCT_DETAILS&tsr363&destination=/app/sfd/cat/pro.jsp%3Fid%3D77992%26slotName%3Dnull%26homeRef%3D
What about the cabling? According to this website http://www.kevinboone.com/cableselection_web.html 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.
--
Malc
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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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Andrew Gabriel
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On Wed, 21 Mar 2007 19:32:35 GMT, "malc"

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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FKruger wrote:

IIUC, the advice to fit 10 mil is quite recent and many <10kW showers are around that have been run in 6 mil. After all, the thing is only going to be on for a few minutes, and possibly only a few minutes a day and the cable dissipation is only going to be a few watts per foot.
But having an MCB keep tripping (I really can't see the OP constantly rewiring fuses or fitting replacments, so I guess it is an MBC) - isn't on. Apart from anything else, it means finishing off the shower with cold water or leaving a load of shampoo in your hair...
So the OP can either fit a bigger MCB and hope that nothing catches fire or melts and hope that any fault doesn't leave the thing live, just as the tresemme hits the tresses..
Or call in a proper electrician, who will no doubt suck teeth, rewire in 10 mil give an inspection certificate and leave the OP with a big bill and a lot of peace of mind.
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