Electric Shower

Postby MikeP » Thu Mar 22, 2007 1:58 pm

Just joined and have already done some reading through your related projects.

My current project is to add an electric shower in an outhouse serving campers in our field. Present supply is totally inadequate (2.5mm2 supply) so will have to rewire from main house consumer unit which uses fuses but no MCBs or RCDs.

Total load in outhouse (approx. 25m cable run from main CU) will be:

8.5KW electric shower
1HP swimming pool circulating pump and 1kw water heater for hot water to wash basin supplied via fused spurs.

2 off double ganged 13A power sockets for power tools

Lighting circuit

Propose to fit a 40A RCBO adjacent to main CU in house feeding a local CU in the outhouse via 10mm2 SWA cable.

Guess this new CU should be three way (can't find a source for one of these).

1. Seperate supply to shower (40A)
2. Power circuit for pump, water heater and power sockets (16A)
3. Lighting circuit (6A)

I am a graduate engineer and feel competent to do the installation. Does my spec look OK?

Can I just call a Part P registered electrician to check it out and do the final wiring to my main board without notifying Building Regs Dept?

My only concern is whether my main supply, switched and fused at 60A is sufficient to take the new load bearing in mind 2 washing machines, spin drier, dishwasher, kettles in 5 bedrooms, fan oven, 2 central heating pumps, underfloor heating in conservatory (1.5kw) and bathroom (1kw)plus a triple power ring main and triple lighting ring (We have converted our second floor to a self-contained flat - hence the 3rd set of rings). We run a guest house so a lot of the load could be on at any one time.
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Simply Build It

Postby sparx » Sun Mar 25, 2007 9:47 pm

short answer..a part p electrician cannot legally issue a completion cert. for work he has not done himself!,you may find one prepared to sign it off as his work, but I wouldn't! sorry.
your existing load is on the limit,
your proposed additional load looks ok on a 10mm2
SWA over the distance allowing for some diversity,
buy a 4way CU, plus one blank.
Are you sure you only have a 60A main it's unusually small, most are 80 or 100A.
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Postby MikeP » Mon Mar 26, 2007 8:28 am

Thanks. I rather suspected the electrician would have to do the whole job.

Yep, only a 60Amp main fuse. Guess I'll need to get it uprated.
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