how to measure existing shower cable?

That - 1.04 - is the same as in the wiki link I posted, although both should actually be 1.09mm.
Ah ok, it is somethig I've had saved on my laptop for a while, I've not tried verifying the values. In fact there are CPC columns too but I'm sure it needs updating.
upload_2021-6-20_14-7-54.png
 
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so 8.5kw could be fine. but just to be safe i gonna find another 7.5kw shower to replace with as i dont want electrician to replace the cable to higher rating as it will cost a lot of money..
There is no difference in the cable which would correctly be chosen and fitted for a 7.5 or 8.5kW shower.
 
Measure the copper core diameter with a micrometer and calculate the cross sectional area using pi times dia divided by 4. Multiply by the number of strands.
I'm surprised no-one has notice the rather obvious error in this. I thought if it came from Winston you'd be on it like a ton of bricks!
 
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It seems I was wrong and the figures are correct; not sure what I did wrong.
 

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damn, i dumb at math.

each core has 7 copper strands and each copper strand is 1mm
no idea how to calculate the cross sectional area. i think i'll leave it and get an electrician to find out for me.
damn, i dumb at math.

Use a calculator then.


each core has 7 copper strands and each copper strand is 1mm
no idea how to calculate the cross sectional area.

I told you in post 3.

But pi x1 x1 divided by 4 x7= 5.5 mm2. I guess it is 6mm2 and you didn’t measure the dia accurately.
 
You wrote " diameter" and also "dia" are these different things or just another bit of lazy writing by you when imparting low value advice.,

Suppose the OP does not have a micrometer, would you advise him to buy or hire one

I’m not the first one to use abbreviations on forums. Why don‘t you hassle anyone else?

What is low value advice about basic schooldays maths?

Did you not see his digital callipers in post 5?
 
There is no difference in the cable which would correctly be chosen and fitted for a 7.5 or 8.5kW shower.
4mm² + 32A OCD will generally just be acceptable for 7.5KW but not 8 KW although there are many 8.5KW showers running on such an arrangement.
 
I don't know where this table originated but generally it seems to work
As for 'where it originated', it looks very much as if it is a copy of what I uploaded to the DIYnot wiki years ago (that is, when I could actually access {to edit} the wiki - I thought that was the idea of 'a wiki'?!).

Kind Regards, John
 

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