Shower Cable

[JohnBoyII]

Hi,

I'm connecting a 10.5KW Triton electric shower; 45mA MCB. The cable is 16mm, found one at Screwfix and one at Toolstation

Screwfix: PRYSMIAN 6943X BLACK 3-CORE 16MM² ARMOURED CABLE 25M DRUM (93861)
(https://www.screwfix.com/p/prysmian-6943x-black-3-core-16mm-armoured-cable-25m-drum/93861)

Toolstation: Pitacs Twin & Earth Cable (6242Y) Grey 16.0mm2 Drum
(https://www.toolstation.com/pitacs-twin-earth-cable-6242y-grey/p90079)

Are they both the same?, the Toolstation isn't armoured but costs about half.

Cheers,

 

[Adam_151]

No- one is SWA, the other is twin and earth. Terminating the 16mm armoured at a pullcord switch might be tricky....

I'd have a look at the design again btw, what correction factors are you applying to need 16mm?, terminating might be tricky might be better to look at the route and see if there is a better way to not need to go as big as 16mm

 

[JohnBoyII]

I was going to use a 10mm cable but when I Googled it most said that above 10KW you had to use a 16mm cable. Is a 10mm cable OK?

I'm not using a pullcord switch. Instead using a MK LOGIC PLUS 50A 2-GANG DP CONTROL SWITCH WHITE WITH NEON (15973) from Screwfix, fitted outside the bathroom.

 

[blup]

If its a short run and not buried in insulation, will be fine..

Blup

 

[Risteard]

You clearly don't know what you're doing. Get an Electrician immediately.

 

[JohnW2]

I was going to use a 10mm cable but when I Googled it most said that above 10KW you had to use a 16mm cable. Is a 10mm cable OK?

If it's not buried in thermal insulation or suchlike,it quite probable that 6 mm² cable would be adequate. !0 mm² certainly would, and there's no way that you would need 16 mm².

As has been said, you really need to employ someone who understands these things, particularly given that the sources you've been using are not providing correct information. Apart from anything else, making the electrical connections to a shower is (by self-fulfilling definition) 'notifiable work', if you are concerned about staying on the right side of the law.

Kind Regards, John

 

[noddy997]

If it's not buried in thermal insulation or suchlike,it quite probable that 6 mm² cable would be adequate. !0 mm² certainly would, and there's no way that you would need 16 mm².

As has been said, you really need to employ someone who understands these things, particularly given that the sources you've been using are not providing correct information. Apart from anything else, making the electrical connections to a shower is (by self-fulfilling definition) 'notifiable work', if you are concerned about staying on the right side of the law.

Kind Regards, John

6mm cable for a 10.5kw? Not a chance!

6mm is sufficient for a 7.5kw

The OP would also need an appropriate MCB and this along with the cable is calculated on length of run.

 

[EFLImpudence]

10.5kW @ 240V is 43.75A (slightly less at nominal 230V).

Current carrying capacity, method C of 6mm² T&E 47A.

 

[JohnW2]

6mm cable for a 10.5kw? Not a chance!

The "10.5 kW" will, almost inevitably, relate to 240V, hence about 41.9A at 230V (the nominal voltage we uses for design calculations)?
The CCC of Method 6mm² cable is 47A
What's your problem with that? 41.9 is definitely less than 47.

Even if it were10.5 kW at 230V (and I've never sen a shower like that), the current would still only be about 45.7A - so, again,Method C 6mm² would be OK. - again, 45.7 is less than 47.

6mm is sufficient for a 7.5kw

It certainly is. So is 4mm² (Method C CCC = 37A).
(if, as usual, it's 7.5kW at 240V, that's about 29.9A at 230V; if {very unusually} it's 7.5 kW at 230V, that's 32.60) - both 29,9 and 32.6 are less than 37.

The OP would also need an appropriate MCB and this along with the cable is calculated on length of run.

What is that nonsense? What has 'length of run' got to do with the MCB rating?

If you're going to offer information or advice, it really ought to be correct!

Kind Regards, John

 

[noddy997]

What is that nonsense? What has 'length of run' got to do with the MCB rating?

If you're going to offer information or advice, it really ought to be correct!

Kind Regards, John

I think the only nonsense was from yourself stating 6mm is fine for a 10.5kw shower??!

You've not seen a 10.5kw shower?! Don't know where you have been then...

 

[EFLImpudence]

That is not correct.

A lot of flats have 10mm² as their supply cable for everything.

 

[JohnW2]

I think the only nonsense was from yourself stating 6mm is fine for a 10.5kw shower??!

It wasn't nonsense as I indicated with the figures (as did EFLI)

You've not seen a 10.5kw shower?! Don't know where you have been then...

That's not what I said. I've seen umpteen 10.5 kW showers, but I have never seen one which was "10.5 kw at 230V" - they invariably quote what the power would be at 240V (which corresponds to about 9.6 kW at 230V), but our design calculations are based on 230V

 

[Murdochcat]

If a new cable is required, then for the small extra cost to install 10 mm over 6 mm does make sense

 

[EFLImpudence]

If a new cable is required, then for the small extra cost to install 10 mm over 6 mm does make sense

Well, it doesn't actually - make sense, that is. It is just a waste.

 

[Murdochcat]

Well, it doesn't actually - make sense, that is. It is just a waste.

Disagree 100%

Have you seen the amount of loft insulation people are piling over their loft cabling?