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 .

 

[Guitarist]

i cant be bothered to read through them 10 pages but has anyone thought what the manufacturer wants to keep the warranty in place normally correct fuse rating to the bs7671 and an rcd in place "just my 2penny worth"

A lot of shower manufacturers state a minimum cable and MCB size. All this has been said so many times before, yet still people are arguing about whether to work from "experience" or adhere to the regs! We know that everything has a safety margin built-in, but that's exactly what it's for, safety.
I think that the phrase "well, the last house didn't burn down", is not going to be much use if it all goes belly-up.

 

[telectrix]

when we look at it, so a 6mm cable is installed method C. it is perfect for the situation at time of installation. OK, so in the future a muppet might cover it in itchy snot, thus derating it's CCC. but, in the future rats/mice may infest the loft, so do we install SWA or cable in steel conduit? client may, in the future, get a plumber to install a 15kW shower, do we allow for that?

 

[Engineer54]

I'm just wondering how many of these manufactures stated KW ratings are actually achieved in the real world??

 

[telectrix]

exactly.

 

[Dave 85]

Youre correct of course but your example is out of context to the original post.
The issue that was debated at the start is regarding utilizing an existing cable so as to reduce cost / inconvienience to the customer in having a bigger cable installed.
Its a judgement call that each person will assess differently , but in my experience a 9.5kw shower will run off 6mm with absolutley no problems for years , regardless of any calcs you want to throw at it.

And here we have the difference between a proper sparky and a regs jockey.

 

[Top Cat]

I'm just wondering how many of these manufactures stated KW ratings are actually achieved in the real world??

I posted a thread about a month ago where i accidentally put a temporary socket on a 6Amp RCBO. A 3Kw kettle was used all day long and it didn't trip. Someone said to put an Amp meter on it, i did and got 9.5 Amps so just shows that elements are not always what they apear to be!

 

[steveberry11]

What an insult to good electricians. A proper electrician will always follow the green book. Why have regs if you second guess them they are there for a reason. To protect you and the customer. In law your only defence is that you carried out your work to the current regulations at the time of installation. As the electricity at work regs state. This will form part of your EIC. I have not yet seen a EIC with a tick box with the wording how were cables sizes worked out GUESSED or CALCULATED perhaps they should it is not only about saving the customer money. Is it not our duty to ourselves and our customers to give them the best job possible and to the current regulations. If we do not do this are we no better than DIYers Perhaps it is a judgment call if you can't calculate cable sizes.

 

[telectrix]

all very well there. perhaps then the manufacturers of showers could then be made to calculate the KW ratings instead of guessing them, as i've yet to see 1 that draws the stated wattage.

 

[sedgy34]

A lot of shower manufacturers state a minimum cable and MCB size. All this has been said so many times before, yet still people are arguing about whether to work from "experience" or adhere to the regs! We know that everything has a safety margin built-in, but that's exactly what it's for, safety.
I think that the phrase "well, the last house didn't burn down", is not going to be much use if it all goes belly-up.

the scams would love this thread saying yep thats why we are here boys

 

[Guitarist]

And here we have the difference between a proper sparky and a regs jockey.

I think you have to be a bit careful with comments like that Dave. There are many times on here when sparkys who know the regs inside-out help the ones who claim to be "experienced".

 

[randym68]

also lets all remember we all use a nominal 230V to calculate Ampere, in reality most supplies are 240-249 V , which is 39.5A to 38.5 A, as Richard Burns says clamp it on start up when amps is highest, i have had 20 meters 2.5mm at 27A and no change in temperature, so 6mm will take at least 60A, make sure if cable goes in loft no insulation can be put over cable, and put a note in the consumer unit that must remain 40A cover your self. also do a Zs at the shower itself , i have had exactly same thing on a 5m run, so in theory passes but the Zs failed, so that means it had to be upgraded to 10mm.

does anyone else wonder why they don't do 8mm , seems most would find it useful in domestic. especially showers and ovens/hobs.

 

[Silly Sausage]

does anyone else wonder why they don't do 8mm , seems most would find it useful in domestic. especially showers and ovens/hobs.

A pair of 4 mils in parallel

 

[telectrix]

we used to have the very thing 7/044 , till the foreign metric rubbish took over. 50A and still not warm.

 

[randym68]

oh archy nice thought but i have replaced many a 2x 4mm in parrallel, (and due to poor fitting really) load transfered over to one cable and melt down..... really don't like using paralleled , which i know is really a ring with one point....just seen too many issues, of one cable damaged or not good connection and transfer/share load over.

 

[trev]

He wasn't serious Randy