Triton T80si 8.5kW Electric Shower

[joeluke]

New 10 months ago, today 30w fuse in the main fuse box in the house went while shower was in use

Changed fuse and the the blown one was very hot

Second time this has happened since shower was fitted

Any ideas why this might be happening would be appreciated

[jg96]

A 8,5 Kw shower will draw a current of around 34 amps so your 30 amp fuse is overloaded. I would advise getting an electrician to have a look because if this shower replaced one of a lower wattage the wiring and consumer unit may not be up to it either

[joeluke]

Thanks jg, could I not just put a higher wattage fuse in?

[Buenchico]

Possibly because an 8.5KW appliance, on a 230V circuit, will draw 37 Amps! (So it's hardly surprising that a 30A fuse gets hot and blows).

You should have a 45A residual circuit breaker (not a fuse), and 10mm cable.

Chris

[ChuckFickens]

No!

Get the cable checked first to make sure it is up to the job for the current and length of the cable, if you put a higher rating fuse in and the cable isn't upto carrying the higher current you'll have a nice little fire on your hands!

[Buenchico]

I'm guessing that your shower was installed as a replacement for a lower-powered one. If so, you've probably got only 6mm cable (which presents a fire risk), together with the incorrect circuit protection. The whole circuit should have been replaced, using 10mm cable and an appropriate RCB.

[ChuckFickens]

Though if you have got 6mm cable at the moment (which would definitely need replacing if you have) then I'd suggest getting 16mm run through so you've got a little leeway in case you want to upgrade the shower again in the future.

You'd also need 16mm with your current shower if the cable length happens to be above 70metres (though you'd need to be living in a huge house to get the shower 70metres away from the consumer board!)

[joeluke]

Thanks for the advice guys.....Chris you're right, shower was replacement for lower power one, young guy who fitted new one didn't mention any of this

So I need an electrician? Any idea of how much that work might cost?

[ChuckFickens]

Nobody can answer that as we have no idea how far away the shower is from the consumer board or how easy/hard it would be to get the cable through.

Though I'd be tempted to contact the people that installed the shower and insist they come back and make the installation safe free of charge, because they have left you with an installation that is not upto safety regs at the moment.

[joeluke]

Shower approx 20ft from fuse box

[joeluke]

Installed by a plumber, should I have got a sparky to do it instead?

[ChuckFickens]

Regardless of who done it the job should have been done safely, and if they put in a 8.5KW shower on a 30amp breaker/fuse and possibly 6mm cable (we don't know that at the moment) then it has not been done safely.

I would personally check the cable size that is used and then contact the plumber and insist they come back and make the job safe. If you do decide for whatever reason to simply get it sorted another way then I can't help you with costs, but I do know you can save a bit if you can run the cable through yourself and then just leave the ends for a sparky to connect up.

[joeluke]

Cheers chuck......not being electrically minded though how do I check cable size?

[BRIGHT SPARK]

Get a REGISTERED sparks in to calculate the design current for the circuit and quote to upgrade the cable (if req)....Upgrade the protection..i.e mcb and rcd or rcbo.when completed you must get a COMPLETION cert and local building control must be notified...dont shoot the messenger!!!

[The Builder]

Joe ................. the others are on the ball as usual ........... just one thing, cable length is not the only factor. Just as important, if not more, is where the cable runs. Through insulation, buried in plaster, grouped with other cables, etc..............
This can de-rate a cable considerably, even to the point where a 10mm cable may not be enough.
What most people don't realise is that a protective device (fuse, MCB etc) is not just there to protect you. It also protects the cable from overloading, as the A-team have already said :o)

[The Builder]

............ sorry BS ................. sneaked in while I was typing.........

[The Builder]

One thing BS ............... B/control don't have to be notified if a Part P registered elec is used :o)

[BRIGHT SPARK]

TB.......the registered sparks has to notify them

[The Builder]

Is that right BS?
OK ......................... thanks for that :o)

[BRIGHT SPARK]

Sorry TB...yes they give you 30 days to file the notification with local BC.and charge a fee for the privelige.When the nasty man from the NIC comes to see us he has all our notifications on his blackberry and checks them against all our domestic certs.If you have gone over the 30 days it starts to cost a lot more........how many havnt you sent!!!