Electric shower upgrade 7 to 9.5kw


Postby cleo273a » Sat Jan 03, 2009 5:21 pm

Current wire is 6.5mm2 off a 32amp MCB. Do I need to change it when I upgrade to 9.5 kw shower?
cleo273a
Rank: Labourer
Progress to next rank:
25%
Posts: 2
Joined: Sat Jan 03, 2009 4:38 pm

Sponsor

Simply Build It

Postby thedoctor » Sat Jan 03, 2009 10:17 pm

Please read our projects on Part P of the building regulations and the one on connection an electric shower. Both can be found in our DIY Projects section at www.diydoctor.org.uk/projects.htm
thedoctor
Posts: 2461
Joined: Sat Apr 08, 2006 12:15 pm

Postby ericmark » Sun Jan 04, 2009 4:22 am

Cable sizes are normally 4mm², 6mm², 10mm², 16mm² not sure how you get 6.5mm²? But 6mm² can be anywhere between 23.5 to 47 amp rated according to how installed. If we consider Reference Method 100# (above a plasterboard ceiling covered by thermal insulation not exceeding 100 mm in thickness) then 34 amp is limit so 32 amp MCB is correct for cable.
10mm² = 45 amp
16mm² = 57 amp
Moving to showers 7Kw = 30.43 Amp and 9.5Kw = 41.3 Amp
How ever if one looks at the chart for a 32A MCB at 41.3 Amp it should hold for 10,000 seconds in other words a couple of hours before tripping. In practice it's not so cut and dried but it would still work for a while before tripping. The MCB may get damaged over time and slowly you shower time would get reduced.
However most electricians would not fit a 9.5Kw shower on 6mm² cable and would insist on fitting 10mm² and the same with the LABC so since it's not like for like and you would need to register the change by using a register electrician or applying to the council under the Part P regulations in real terms you would need to up grade. Also in doing so you will need to comply with latest regulations and it will need RCD protection if not already installed.
By time you add all the costs together using a plumbed thermostatic valve may be cheaper? and will in the main be a better shower I would not use electric sprinkler I want a proper shower.
Yes I know many people will not comply with Part P but insurance will be void and house sale will be affected so you need to be aware.
In the main as long as the correct size MCB for cable is used overloading will only cause the MCB to trip and will not cause danger as the trip will open before the cable overheats but this would only be the case if the cable is installed correctly in first place. If installed originally using Reference Method 103# (in a stud wall with thermal insulation with cable not touching the inner wall surface) then it may already be overloaded [Rating for 6mm² would be 23.5 amp] in which case fitting a 9.5Kw shower could cause a fire. Since in many houses there is no installation certificate available to tell you how it was installed you may be introducing a real fire risk. It is because of these latent risks that Part P is required to protect you although many see it as a stealth tax.
I would not recommend DIY but I realise many will which is why I have tried to be as honest as I can and not just say you can't do it under Part P.
Do remember when electricians fit things we also test them with meters costing around £750 so most DIY with electrics is really taking a chance and hoping you make no mistakes.
Up to you!
Eric
ericmark

Postby cleo273a » Sun Jan 04, 2009 3:36 pm

Thank you for you comprehensive reply. I am most grateful. You have given me lots to think about. I could go with your mixer valve option, as we have a combi boiler, but my partner has already bought a bargain 9.5kw replacement shower. It looks like this "bargain" may not be such a bargain after all. Thanks anyway.
cleo273a
Rank: Labourer
Progress to next rank:
25%
Posts: 2
Joined: Sat Jan 03, 2009 4:38 pm

Postby ericmark » Mon Jan 05, 2009 11:40 am

I would use Combi boiler as a 27Kw shower from Combi is far far better than trickle from 9.5Kw it is what I have and I would never go back.
Eric
ericmark

Display posts from previous
Sort by
Order by



  • DIY How to Project Guides

  • DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!



 


  • Related Topics