9.5 kw shower on 6mm ?

[jonthesparks]

just been to a job , saw that the shower 9.5 kw is on 6mm t&e the cable goes in the wall and under floor boards ,No insulation, to the board (A cable run of no more than 10 m) . I said downgrade the shower to 8.5 max. Is it really necessary ? never quite sure , its borderline to me .

 

[Des 56]

Hello, I’m the member of parliament for East Dulwich. I can drone on for hours and hours about nothing in particular, in fact after a couple of houre I’ve usually forgotten what I started talking about. BUT I still keep droning on and on and on……… Er what, where was I, oh yes I remember…. Damn I can’t find my notes about what I was talking about……. Zzzzzzzzzzz

That has gotta be from my favourite of all time comedy Monty Pythons Flying Circus ?

 

[Guitarist]

Its been suggested in this thread, that if the shower is over 8KW they just go ahead and install a 10mm cable.( or even for a 9.5KW shower)I put it to you that its much "Greener" to install an 8.5KW shower on a 6mm cable.The company I worked for, only installed 8.5KW showers in Housing association properties.There must have been enough flow, as we never had any complaints.I think its much Greener for water usage and energy usage and in lower cost of materials(6mm cable instead of 10mm), to install a 8.5KW shower.( Besides its mighty difficult to terminate the 10mm in the isolator). + Austerity and all that??I think anything above 8.5KW should be banned or maybe taxed? on the grounds that it contributes towards Global Warming!!!!

Just installed a 7.5 Kw in my own bathroom on a 6mm cable. Flow is a little slow on a cold morning, but it doesn't use much water

 

[sedgy34]

i thought wet string would comply.

what about the bonding

 

[SPARTYKUS]

what about the bonding

Nah, that shower is exempt.

Its double insulated, honest

 

[Moses]

Just installed a 7.5 Kw in my own bathroom on a 6mm cable. Flow is a little slow on a cold morning, but it doesn't use much water

I'm sure you could have got away with a 4mm cable and a 32A CB.
Your 6mm cable is well over rated!!!!!

 

[Guitarist]

I'm sure you could have got away with a 4mm cable and a 32A CB.
Your 6mm cable is well over rated!!!!!

Don't tell the DIY'ers that mate. They will think you are serious and not factor in all the derating factors.

 

[mojowaky]

If you did go ahead with the 6mm instead of 10mm, then I would recommend you use a 100ma or 300ma RCD to protect against fire risks of the cable breaking down, as you get fire/thermal protection on cabling with a 300ma RCD. I doubt the shower will ever be on max temp for long enough to draw the full 9.5kw anyways (real life example of diversity), 6mm is likely to be enough.

 

[PigletJohn]

Oops, I see Geoffsd has already covered it on page 7.

That'll teach me not to click on links in emails without checking.:dunce2:

 

[Darkwood]

If you did go ahead with the 6mm instead of 10mm, then I would recommend you use a 100ma or 300ma RCD to protect against fire risks of the cable breaking down, as you get fire/thermal protection on cabling with a 300ma RCD. I doubt the shower will ever be on max temp for long enough to draw the full 9.5kw anyways (real life example of diversity), 6mm is likely to be enough.

Not sure where your coming from with this post but the shower will already be required to have 30mA rcd protection, the standard shower is a instantaneous heater and temp' is regulated by adjusting flow rate so if shower is on its drawing 9.5Kw irrespective of the duration you have it on for.

 

[Guest55]

Future note to new forum users :

Please let this thread die , at 8 pages long there is little of use to add that hasnt been argued to death.
;-)

 

[Dave 85]

Convince them they have to upgarde the cable or downgrade the shower or the house will burn down. Quote them a fortune. Then tell them they need a rewire...else the house will burn down. Quote them a fortune.

Robbing people blind is fine as long as you convince yourself its for their own safety......

 

[trev]

That's going to look great on open forum isn't it
People have enough trouble trusting tradesmen without nonsense like that being in public view

 

[Dave 85]

I feel that if you tell them and put it in writing then your covered - the owner said no to bigger cable and they knew if they where going to have it insulated then the cable needs upgrading. Its on their back then if the place burns down - you have noted that no insulation in place and action to be taken and they ignored your advice!

Have you ever tried running 40 amps down a 6mm T&E and then dropping a sheet of fiber glass on it? (or getting a mouse to) Does the cable catch fire when you do this?

Why dont you make them sign an advisory form stating that if someone puts a petrol bomb through their letter box and the house burns down, that you offered to weld shut their letter box but they refused. Just to cover yer back like....

 

[nickblake]

Convince them they have to upgarde the cable or downgrade the shower or the house will burn down. Quote them a fortune. Then tell them they need a rewire...else the house will burn down. Quote them a fortune.

Robbing people blind is fine as long as you convince yourself its for their own safety......

Jesus you'll end up on rouge traders with an answer like that , not really acceptable

 

[trev]

My point exactly Nick

 

[Dave 85]

That's going to look great on open forum isn't it
People have enough trouble trusting tradesmen without nonsense like that being in public view

Come on Trev, you know I'm only messing about. Just annoys me people advising clients to fix things that arn't broken.

 

[trev]

Dave you may well be messing about but put yourself in a potential customer's position. A lot of people are nervous enough about tradesmen ripping them off and we get plenty coming on here looking for advice.

 

[trev]

I agree that there's an over reaction to fixing things that aint broken but you can't tell people's inflection from what they type mate.

 

[Guest123]

Lets not get silly now chaps, remember, potential customers could also be reading this thread........:wink5:

 

[telectrix]

agreed . after all, we're electricians, not plumbers.

 

[somersetsparks]

Just to add my tuppence worth,
I have seen many, many 8kw and above showers wired in 2.5mm flex from the isolator to the actual shower unit in my time testing, none of which showed any signs of damage, poor terminals and terminations cause many more,
I think in an ideal world there should be a 'domestic shower diversity' added to the regs, it irritates be to give a code 6mm supplying showers in houses, in fact I often give it a code 3 rather then 2 if there is no heat damage.

 

[Guest55]

Just to add my tuppence worth,
I have seen many, many 8kw and above showers wired in 2.5mm flex from the isolator to the actual shower unit in my time testing, none of which showed any signs of damage, poor terminals and terminations cause many more,
I think in an ideal world there should be a 'domestic shower diversity' added to the regs, it irritates be to give a code 6mm supplying showers in houses, in fact I often give it a code 3 rather then 2 if there is no heat damage.

Dont understand why you would code it at all ?
On what grounds ? for what rating of shower is 6mm unacceptable ?

 

[sedgy34]

Thread closed!!!!!!

 

[somersetsparks]

Thread closed!!!!!!

Nearly fooled me!
Biff55, I meant when they are on 40MCB's with referencve method 101 or A (or the dreaded 103... arhh!)

 

[Paul P]

Agree with robd , as a fixed load , 9.5kw @ 230v pulls 41.3A
i wouldnt replace cable for an extra 1A for a few mins.

As a shower is a fixed restance i think you will find it rated at 9.5kw @ 240v so only 39.58A

At 230v it would be a 8.7KW shower so only 37.9A