Size of shower cable

[Bensen]

Hey what kilowatt showers can be feed off 6mm cable and which need 10mm? I guess the distance from the fuse board also needs taking in to account?

 

[pennychew]

Very true, and the 8.5 kw shower which is working at my parents house wired in a 6mm2 cable which is at least 12 years old now must be switched off immediately as well.

Not when one of thems using it though, that would be mean

 

[shanky887614]

Using 6mm to supply an 8.5kw shower is WRONG.
Unless your a qualified electrician you should NOT be doing the job because of the many variables, and safety is paramount.
But real world scenario is often very different, and in your working life you will often come across situations that conflict with calculations, and regs.
When that happens you need to ask, how so !!
As an example there are situations where an 8.5 kw shower will be fed from a 6mm cable on a 32 amp mcb over many years and show no signs of thermal damage, or have given any problems to the user.
Calculations and regs will say otherwise, real life is often very different.
Of course your maxing these situations out, which is far from a good idea.
next time your running an 8.5kw shower.
Check your 230v supply and see what your really getting. Clamp test the shower and see what its really pulling.
Then maybe you will see why sometimes 6mm will appear to suffice despite all the theory.
ITS still WRONG and I don't dispute that but it is possible.
My comments are for qualified electricians, not for Joe public.
So Joe public take note. The fall out I am receiving is to protect YOU not me.

your a fool if you believe that, your cable calcs will prove otherwise, an 8.5kw shower is a 37amp load so 40a mcb will do which means 6mm is fine not allowing for any derating factors

 

[baldsparkies]

your a fool if you believe that, your cable calcs will prove otherwise, an 8.5kw shower is a 37amp load so 40a mcb will do which means 6mm is fine not allowing for any derating factors

Here we go again.
Why conclude that someone is a fool without thinking your statement through.
How can you possibly say that 6mm is fine, and then follow up by saying (by not allowing any de rating factor)
That's the entire point of being a qualified electrician.
You WILL include de rating factors into your calculations, joe public will not.
What I am saying is that its wrong to make a blanket decision regarding 6mm.
Hence my comment (Broadly speaking, up to 8.5kw 6mm beyond that 10mm) but and its a big but other variables have and should always be taken into account.
If your unsure what those variables are or how to apply them then consult a qualified electrician.
I sometimes feel that often comments are miss-read, miss-understood, or even miss-phrased by the poster.
But I find it a bit sad and disappointing when there are people that you respect, waiting to pounce on your every word with the sole intention of calling you a fool, blind, or even incompetent.
Nothing I have said is either wrong, or inaccurate.
Sometimes you just need to think outside the box, and give the other guy a bit of breathing space.
As qualified electricians we should all be able to do this without throwing around insults based on our individual points of view or opinions.
As said real world it simply doesn't work that way.
That's why on the forum you will call a 6' 6" bloke all muscle and weighing 18 stone a dick head.
And in the real world, keep it to yourself and call him a dick head under your breath lol xx

 

[Guest125]

in this case what the op was asking is ohm's law, the basic's of the basics.


V=R/I
I=R/V
R=IxV

bassically to start with a 10kw shower would be 10,000 / 230 = 43Amps

so now you have your design current for your cable calc.

the cable you need for a 10kw shower depends on installation methods (clipped direct)

if it has loads of insulation along the route and other factors you might need a 16+mm cable (this is why we calculate cables in the first place)


and to answer your question, the members here get that bored and wound up from giving people the same advice everyday on how to wire a shed they get ratty

If I do not want to give advice then I just don't. Surely this would be a better way to approach a thread that someone feels is not worth their time rather that slagging off other posters?

 

[Guest125]

Using 6mm to supply an 8.5kw shower is WRONG.
Unless your a qualified electrician you should NOT be doing the job because of the many variables, and safety is paramount.
But real world scenario is often very different, and in your working life you will often come across situations that conflict with calculations, and regs.
When that happens you need to ask, how so !!
As an example there are situations where an 8.5 kw shower will be fed from a 6mm cable on a 32 amp mcb over many years and show no signs of thermal damage, or have given any problems to the user.
Calculations and regs will say otherwise, real life is often very different.
Of course your maxing these situations out, which is far from a good idea.
next time your running an 8.5kw shower.
Check your 230v supply and see what your really getting. Clamp test the shower and see what its really pulling.
Then maybe you will see why sometimes 6mm will appear to suffice despite all the theory.
ITS still WRONG and I don't dispute that but it is possible.
My comments are for qualified electricians, not for Joe public.
So Joe public take note. The fall out I am receiving is to protect YOU not me.

We are putting in new shower supplies in at Clapham.

8.5kW = 37A
40A OCPD required
single cable in surface trunking has a max of 41A for 6mm cable.

6mm cable it is then...

 

[Octopus]

We are putting in new shower supplies in at Clapham.

5.8kW = 37A
40A OCPD required
single cable in surface trunking has a max of 41A for 6mm cable.

6mm cable it is then...

So you are back and immediately you are being a dxck.

Please don't hand out detailed advice on the public forum

Thanks

 

[Guest125]

Here we go again.
Why conclude that someone is a fool without thinking your statement through.
How can you possibly say that 6mm is fine, and then follow up by saying (by not allowing any de rating factor)
That's the entire point of being a qualified electrician.
You WILL include de rating factors into your calculations, joe public will not.
What I am saying is that its wrong to make a blanket decision regarding 6mm.
Hence my comment (Broadly speaking, up to 8.5kw 6mm beyond that 10mm) but and its a big but other variables have and should always be taken into account.
If your unsure what those variables are or how to apply them then consult a qualified electrician.
I sometimes feel that often comments are miss-read, miss-understood, or even miss-phrased by the poster.
But I find it a bit sad and disappointing when there are people that you respect, waiting to pounce on your every word with the sole intention of calling you a fool, blind, or even incompetent.
Nothing I have said is either wrong, or inaccurate.
Sometimes you just need to think outside the box, and give the other guy a bit of breathing space.
As qualified electricians we should all be able to do this without throwing around insults based on our individual points of view or opinions.
As said real world it simply doesn't work that way.
That's why on the forum you will call a 6' 6" bloke all muscle and weighing 18 stone a dick head.
And in the real world, keep it to yourself and call him a dick head under your breath lol xx

There does appear to be a few on here that know full well that a post is meant generally and they enjoy to show how big their BS7671 testicles are and pick holes rather than just give their version of a solution.

 

[Guest125]

So you are back and immediately you are being a dxck.

Please don't hand out detailed advice on the public forum

Thanks

Please do not call me that.

It was NOT advice for the Op but a direct REPLY to the quote saying that a 6mm cable could not be used. The reply was quoted so I though that would be obvious. On top of that I wrote WE. As in WE are doing this. WE are qualified electricians. and WE are doing the work.

 

[shanky887614]

Please do not call me that.

It was NOT advice for the Op but a direct REPLY to the quote saying that a 6mm cable could not be used. The reply was quoted so I though that would be obvious. On top of that I wrote WE. As in WE are doing this. WE are qualified electricians. and WE are doing the work.

i think you have a typo mate.

i think you mean 8.5

 

[Guest125]

i think you have a typo mate.

you put 5.8kw i think you mean 8.5

Yeah sorry. I will now climb off my high horse.

 

[telectrix]

We are putting in new shower supplies in at Clapham.

5.8kW = 37A
40A OCPD required
single cable in surface trunking has a max of 41A for 6mm cable.

6mm cable it is then...

well at least get ohm's law right. 5800/230 = 25.22 A according to my arithmetic.

 

[shanky887614]

well at least get ohm's law right. 5800/230 = 25.22 A according to my arithmetic.

ah but it wouldnt be a 5.8 would it.

i have only come across 6,8.5 or 10kw electric shows

the manufacturer's like round nunbers

 

[Guest125]

ah but it wouldnt be a 5.8 would it.

i have only come across 6,8.5 or 10kw electric shows

the manufacturer's like round nunbers

Talking od typos........LOL

 

[baldsparkies]

well at least get ohm's law right. 5800/230 = 25.22 A according to my arithmetic.

Yer right Tel.
But why 230v ?? is this by enquiry, assumption, or a true measured rms voltage.
Thinking outside the box (not recommended for DIY man, go away)
but food for thought never the less.
Be gentle with me no more abuse pleeeeese, lol.

 

[shanky887614]

Yer right Tel.
But why 230v ?? is this by enquiry, assumption, or a true measured rms voltage.
Thinking outside the box (not recommended for DIY man, go away)
but food for thought never the less.
Be gentle with me no more abuse pleeeeese, lol.

if its 250 then it would be less.

its rare to see 220v and even then it would only increase a little

 

[Andy78]

Yer right Tel.
But why 230v ?? is this by enquiry, assumption, or a true measured rms voltage.
Thinking outside the box (not recommended for DIY man, go away)
but food for thought never the less.
Be gentle with me no more abuse pleeeeese, lol.

It is standard practice to use the nominal Uo value for all calculations.

 

[Silly Sausage]

if its 250 then it would be less.

its rare to see 220v and even then it would only increase a little

No no no!
The current will increase with voltage.
The power rating is quoted at a certain voltage.

 

[telectrix]

beat me to it. using 230V will give a worse ( higher) value for current than using the actual ( 235 -240V ) so errs on the side of caution.

 

[baldsparkies]

Its even more rare to see 230v shanks, and often that's the baseline that's used for obvious reasons.
And yet when I dared to suggest 6mm as a possible cable size for 8.5kw I was summary abused ??
Despite that, it will be used. And if Mr DIY is going to use it it's wrong.
But on an electricians forum, and with all other factors taken into account,can and does prove satisfactory in the real world.
So there you have it, some people are getting trashed for saying 6mm, some people quite happy to use 6mm.
Hope others are paying attention here, cus amongst qualified electricians there are indeed differences of opinion, and you know what dependant on the situation both are entirely correct.
And that's the whole point, and no abuse needed.

 

[GEOFF S]

Well if Baldsparkies wasn't bald, he will be now! Crikey, a vague question got a vague answer, like most questions and answers on the forums! All this bickering over such trivia lol. Come on chaps