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 Topic Title: 9.5kW shower on 40A mcb Topic Summary: Created On: 28 August 2012 09:24 PM Status: Post and Reply Linear : Threading : Single : Branch
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 28 August 2012 09:24 PM baronvoncaravan Posts: 30 Joined: 06 September 2010 Good evening all, I'm sure i'll get shot down in flames for even asking this but what mcb/ cable size do you all use if installing a 9.5kW shower? 230V = 41A 240V = 39A It's for a family member and i'm trying to keep the cost down for them and as we all know, cable isnt the bargain it once was 28 August 2012 09:34 PM AJJewsbury Posts: 9771 Joined: 13 August 2003 What voltage does the manufacturer's data say the 9.5kW relates to? The last time I looked it was often 240V (presumably as this yielded bigger numbers which marketing departments seem to like) with a smaller 230V figure in the small print, but just to be safe, I wouldn't assume that. (Technically, a shower is a fixed load, so you can get away with sizing the cable to the shower draw, rather than then MCB size - Zs and v.d. permitting of course.) - Andy. 28 August 2012 09:38 PM daveparry1 Posts: 5268 Joined: 04 July 2007 If it's not an excessively long run and the cable isn't running through insulation 6.00mm cable will be fine (and a 40 amp mcb) Dave. 28 August 2012 10:47 PM baronvoncaravan Posts: 30 Joined: 06 September 2010 Thanks chaps, the run is about 16m in swa to isolator and then T&E to shower so no v.d. or ccc issues on 6mm with 40a mcb. I was just thinking about In>Ib if voltage is on the lower end of the scale. 28 August 2012 10:56 PM AJJewsbury Posts: 9771 Joined: 13 August 2003 I was just thinking about In>Ib if voltage is on the lower end of the scale. If the voltage is low, then the current draw will be lower too. Showers are just simple heating elements - the fixed thing is the element's resistance. You can only read the rated kW figure at the corresponding rated voltage - at a lower voltage the actual kW draw will be lower (and the water won't get so warm). - Andy. 29 August 2012 09:12 PM johnboy6083 Posts: 29 Joined: 25 July 2008 a MCB will draw run indefinately on 1.13x In, so at 41A, a 40A MCB is only 1.025 x In. As the above fella mentioned, its a fixed loads, and as such doesnt require overload protection, just short circuit. I would put it on a 40AMCB, and i wouldnt worry at all about it. cable sized to the load as above.
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