Shop Kitchen Supplies Installation Query

[jordanclarke]

Hi Forum-ers,

I was hoping someone can help me, as I'm stepping out my normal line of work to help a friend.
I'm an electrical fault finder on the railway, but previously did some industrial work and so have BS 2391.
My friend is installing a small kitchen in a shop, the shop fitter has handed him some paper with the following circuits for the cookers, extractor fan and fridges, as follows:
A/ 3KW (Cooker/Grill)
B/ 3KW (Heating area)
C/ 5KW (Cooker/Grill)
D/ 13A Spur 1KW (extractor fan)

There is already a ring main for the fridges.

So my question is- I believe the A/B/C/ can run off a 45A breaker with 10mm cable (run of 5m), which feeds a double pole isolating switch, but is it ok to feed three items off of one isolating switch? I thought there might be a limit of two?
And does the fitter intend to take the spur for D/ off of this one isolator also?

While I am in the electrical field, I don't have much experience with thiese sorts of installations so couldn't really explain it to my friend, so really appreciate any help you can offer.

 

[telectrix]

you could take D as a spur from the ring. as for A/B/C i would run a separate radial for each, each with it's own isolator.
you can then use 4mm or 6mm for each.

 

[SirKit Breaker]

As Tel says mate, but you will need RCD protection. I would do as tel says, but fit a seperate consumer unit with RCBO's for each circuit, this is not the cheapest solution, but if you fitted a RCD protected CU you would loose all circuits if you had a fault, the RCBO route would just trip the offending circuit.

Cheers...........Howard

 

[telectrix]

why RCDs, Howard, unless cable is buried in walls? it's fixed equipment.

 

[SirKit Breaker]

why RCDs, Howard, unless cable is buried in walls? it's fixed equipment.

Fair point tel, but he doesnt state the installation method for the cables. So i have gone worst case scenario.

Cheers...........Howard

 

[telectrix]

touche.

 

[jordanclarke]

cheers for your replies lads. I'll go with radials then. Though I might skip the RCD equipment as running the cables in surface mounted steel conduit.

appreciate your advice!!

 

[jordanclarke]

one more thing please, if i use the 6mm cable i was gonna use 32A mcb for the 5KW and for the 3KW a 25A mcb. does this sound right to you??

 

[Des 56]

The 3 KW heating radial could be run in 2.5mm with a 20 amp mcb if prefered and a double pole switch if its a fixed load

Another method of wiring this area is as found in ready made chip shop ranges
A seperate consumer unit fed by a sub main with circuits local to the loads
It may be more adaptable for any alterations to the cooking area,adding display lighting etc