I am replacing an electric shower. I note that there are now 3 powers available - 8.5, 9.5 & 10.5kw. Will my existing wire which powered the old elec shower be fine for any of these, because if the price difference isn't too much, surely I'm best going for 10.5 - hotter, more powerful, no?
Electric shower cable thickness
- Thread starter Deansplit
- Start date
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What was the rating of your previous/existing shower? It could have been as low as 6kW.
What is the fuse/MCB rating?
What is the fuse/MCB rating?
- //www.diynot.com/wiki/electrics:mcbtocable
- http://www.tlc-direct.co.uk/Book/4.3.1.htm
- http://web.archive.org/web/20080213151445/http://www.kevinboone.com/cableselection_web.pdf
- http://www.tlc-direct.co.uk/Book/4.3.11.htm
- http://www.tlc-direct.co.uk/Book/5.3.1.htm
- http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html
- http://www.tlc-direct.co.uk/Book/8.1.1.htm
- //www.diynot.com/wiki/electrics:part-p
The fuses at the board are all 30a for the showers (lots of them, was a B&B) - I've since disposed of the cranky ol Redring one, so no idea what it was. So from here, how do I ascertain what kW I can go up to - think the cable is 2.5mm, thought that was standard for a shower, no?
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Click on all of the links in my post above and read.
1) There can't really be any such thing as "standard for a shower" when there is no standard rating for showers and the cable required depends on how large the load is, how it's installed, what length it is and what the protective device is.
2) On a 30A rewirable fuse 2.5mm² is good for at most 19.6A and as little as 9.8A, depending on how it's installed, i.e. a shower of 2.35kW - 4.7kW
Just a quick question and excuses my ignorance now!
Should 2.5mm cable really be protected by a 30A fuse unless its a ring?
Should 2.5mm cable really be protected by a 30A fuse unless its a ring?
Depends on whether the fuse is needed to provide overload protection, or just fault protection....
A 30A fuse will not protect a 2.5mm conductor not in ring formation against overload, odd exception aside* and if its re-wireable then technically it won't quite do it even if it is a ring (27A de-rated by the 0.725 factor is a few tenths of an amp below 20A...) , despite it being a standard circuit installed for many decades!
*(assuming cartridge fuse), exceptions include, (1) MI in some circumstances , and (2) XLPE SWA where the switchgear is rated to handle 90C (rare in practicel)
I'm getting a bot lost in all these stats and figs - I've found a shower - it's 9.8kW and the existing cable is 2.5mm - no idea what the orig unit was, it's long since sold for 20 quid! So 'if' buy the 9.8kW shower, am I at risk at just hooking it up to the existing cable, on a 30a fuse? This is really the bottom line.
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I wouldn't; I'm not qualified to do domestic installation work.
Check what size the cable is.
Previously you 'thought' the cable was 2.5mm, and you apparently aren't aware there are larger sizes, so forgive me for talking that with a grain of salt. Perhaps you should hire an electrician to do the work for you?
Sorry, since measured it, yes 2.5mm. Wouldn't dream of hiring an electrician to hook up a shower, the actual process of installation is basic physics, it's just knowing if the cable is OK, and if it's not, being that it's the top floor of a 3 story home it ain't gonna get replaced!
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