New garden office, Cable selection and method...?

[srl-8]

Hello Guys,

I will be installing an electrical supply to a new garden office and I want to run my thoughts about my installation past you all, to see if I have got this right in term of cable selection and load, or if anyone can suggest another way of doing this…

The Office will use the following load, I have rounded all amounts up to be safe.

3 x 1.5 kw heaters = 4500w = 20Amps

8 x 50w down lights = 400w = 2 Amps

4 x computers = (allow 250w per machine) =1000w = 5 Amps

Possible additional usage (microwave/printer/phone charge/fan etc) allow approx 1000w = 5amps

TOTAL AMPS = 32



I plan to install a 10mm PVC multi-core cable from Fuse board, (Protected by a 40 or 45 amp MCB or RCBO) through the house, until outside, then change to 10mm SWA up to the new installation. (Approx 15 meters away)

A new garage board will be installed with rcd in the new office, protecting the relevant new circuits.

(It is yet to be decided if client wants to have a new main fuse board in the house or install a separate unit fed from the Henley block.. The old fuse board is re-wireable fuses and non-rcd. I believe the earth arrangement is PME at this stage.



I would like your opinions and suggestion please

Thanks!

 

[srl-8]

The 10mm will be run under floorboards in the house and the swa will be burried.
I think i will run 10mm 3 core swa, and this will give me the 10mm earth to be sure.

good advice

 

[Engineer54]

The 10mm will be run under floorboards in the house and the swa will be burried.
I think i will run 10mm 3 core swa, and this will give me the 10mm earth to be sure.

good advice

It won't, not if you are still going to use 10mm T&E....

 

[srl-8]

It won't, not if you are still going to use 10mm T&E....

Er.. why not ? why can you not run 10mm T& E under floorboards or have i miss understood??? Same as a shower circuit etc...

 

[RISElectrical]

Because the cpc in 10mm T+E isn't 10mm

 

[srl-8]

Oh right, yes of course, but if I ran 3 core + Earth I would have 3 x 10mm cores... right.

 

[malcolmsanford]

You won't be able to get a 3 core 10mm T+E though.

Can I ask if your an electrician?. Because as I mentioned in post #14 you may find the 4mm CPC is good enough, but you need to do the adiabatic equation to make sure

 

[RISElectrical]

3 core and earth? You would just need the 10mm T+E and then a separate 10mm earth. Basically just ensure that the size of the earth is always at 10mm for the whole run. If that makes sense