3phase dis inb domestic setup

[J.C.E]

looked at a rewire of a 4storey property today (lower,ground,1st,2nd)
they is a 100a 3ph head on lower floor- and there is 2x seperate SP c/u (think there use to be 2x flats)

but is now going to be one house

best option?... to install something like a 8way 3ph amd3 dis board by the head on lower floor and have all my circuits off rcbo's off that (balancing the load evening across the phases)

probaly do circuit wise:

lower floor lighting 6a 1.5
ground lighting 6a 1.5
1st+2nd floor lighting 6a 1.5
lower ground power 32a 4mm radial
ground power 32a 4mm radial
1st floor power 32a 4mm radial(with 2x 3m2 UHF kits)
2nd floor power 32a 4mm radial (with 1x 3m2 UHF kits)
kitchen ring 32a ring/radial
Indcution Hob 32a 6mm
Oven 20a 2.5mm
MW 20a 2.5mm
I.H 16a 2.5mm
Boiler 16a 2.5mm
Alarm 6a 1.5mm
Smokes 6a 1.5mm

no 'building' work is being undertaken as in extensions etc- so no building inspector- would I need a system grade A fire system as a large house or will I be fine will LD3 (smokes in 4x halls and heat in kitchen- all interlinked)

 

[J.C.E]

learn today a bit more..

so 100a 3ph head coming in >> 100a 3ph isolator
then they only used 1 phase into sp meter and henley blocked into 2x sp fuse boards

for a 4storey house (with gas for heating) would you tend to keep simular setup and just use 1 ph into a hager stacked consumer unit with rcbos

or get the client to get a 3phase meter and put a 3ph dis board with rcbo's in?

cheers for help

 

[Andy78]

I'd look at the demand taking into account current measurements and go from there. Seems to be fine for the current usage ?

 

[J.C.E]

I'd look at the demand taking into account current measurements and go from there. Seems to be fine for the current usage ?

nothing heavy

all LED lighting (was going to have 1x circuit circuit per 4 floors)
4mm 32a radials for sockets per 4 floor (normal ammount of points)
32a ring for kitchen
32a for ind hob
2x 20a radials for MW+fan oven
1x 16a for immersion
1x 16a for 2x boilers
on the 1st floor 32a raidal (there will be 2x 3m2 elec ufh in bathrooms)
on the 2nd floor 32a raidal (there will be 1x 3m2 elec ufh in bathroom)

so if I was to calc max demand adding up circuits and x0.4 -that will obviously be >100a

but i am thinking 100a will be ample..

 

[Timbo]

Why 4mm radials? 2.5mm is cheaper and easier to work with.

 

[Spoon]

Why 4mm radials? 2.5mm is cheaper and easier to work with.

Could be cause radial is safer than ring.

 

[J.C.E]

this is the current setup before rewire

3phases from head >> MEM isolator

L3 goes into a henley in the trunking >>which feeds the SWA and that SP meter

the SWA then feeds another meter which supplys a c/u for one part of the house

and the SP meter in the picture feeds another c/u which does the rest of the house (via the orange pyro)

so the old 2x c/u are both on L3 100a

The house is now one- and the client wants one consumer unit in one place- nice and organised

I was thinking to start from scratch

take head tails (only from 1 phase)>> SP meter >> new 100a SP isolator

then a SWA from new 100a SP isolator>> a new hager 20+20 stacked consumer unit with rcbo on the ajacent wall (as the curved ceiling will look craap with trunking/cables

then just leave the other 2 phases unused at the head

thoughts