Best cost effective option?

[Rosco22]

Hi all,

Just deciding what option to go for, it's for a 3phase supply to a large house.
I'm taking a phase to each floor and i beleive i can either terminate into a isolator, and onto a busbar then connect each cable onto that and out to each DB (although isolation would be all or nothing in the future?)
or install a 3phase DB and run each DB off of it with a 63A MCB for each sub main. I guess the latter is probably the best domestic option but any ideas on the matter would be appreciated!

Thanks in advance

 

[monkeyelectric]

I would say the latter in a domestic situation

 

[shocking_eg]

or run a 3 phase to each floor and fit a small 3 phase board to each.

and one 3 phase at the intake with Triple pole MCB's to supply the submains. then you can run smaller CSA submain cables to each floor. ?

helps balance the loads better too imo ?

 

[john999uk]

If it's domestic then surely you will have 3 meters (1 per phase). So can you not go from each meter tails to a 63amp switch fuse then sub mains to a CU on each floor?

 

[shocking_eg]

Why wouldn't a domestic have a 3 phase meter ?

 

[john999uk]

Why wouldn't a domestic have a 3 phase meter ?

I assumed that as the loading would so unbalanced that there would be 3 separate meters is that not the case? Are modern meters better at unbalanced loads?
Only reason I suggested 3 meters for 3 phase domestic is that is what has been suggested to me for my property. While not strictly domestic (5 holiday apartments and 1 domestic in single victorian 3 story building) the loading will be unbalanced.

Just had a look at 3 phase meters. I did not realise that they new ones can just measure each phase KW usage and add up a total usage.
Thanks.

 

[Rosco22]

With regards to the metering it's at the beginning of the drive way and in the house is just a 35mm 4core.

 

[rattlehead85]

Best option would be to run a 16mm2 3 core cable SWA with single phase board to each floor protected by a 63a device from your 3 phase intake position board. Place each floor on a seperate phase/line. This should achieve reasonable balancing providing the load after applying diversity calculates to be roughly the same give or take between 2-5 amps per floor.

 

[Knobhead]

Go for your second option. The metering isn't you're problem.

 

[shocking_eg]

Best option would be to run a 16mm2 3 core cable SWA with single phase board to each floor protected by a 63a device from your 3 phase intake position board. Place each floor on a seperate phase/line. This should achieve reasonable balancing providing the load after applying diversity calculates to be roughly the same give or take between 2-5 amps per floor.

i would have thought running single phases to each floor could make things quite unbalanced.... say for instance.. L1 for the ground floor... kitchen, possible outbuildings all on the one phase.. the most current using equipment would be on one phase then..

i may be wrong ?

 

[Adam W]

i would have thought running single phases to each floor could make things quite unbalanced.... say for instance.. L1 for the ground floor... kitchen, possible outbuildings all on the one phase.. the most current using equipment would be on one phase then..

i may be wrong ?

That's what I was thinking:
L1 - Ground floor lighting, outdoor lighting, garage lighting, oven, kettle, toaster, dishwasher, microwave, fridge, freezer, coffee machine, warming drawer, steam oven, washing machine, tumble drier, large TV, AV equipment, hotplate, central heating pump.
L2 - 1st floor lighting, clock radio, bedroom TV, hairdryer.
L3 - 2nd floor lighting and TV in rarely used guest bedrooms.

Doesn't seem as balanced as it could be.

 

[shocking_eg]

That's what I was thinking:
L1 - Ground floor lighting, outdoor lighting, garage lighting, oven, kettle, toaster, dishwasher, microwave, fridge, freezer, coffee machine, warming drawer, steam oven, washing machine, tumble drier, large TV, AV equipment, hotplate, central heating pump.
L2 - 1st floor lighting, clock radio, bedroom TV, hairdryer.
L3 - 2nd floor lighting and TV in rarely used guest bedrooms.

Doesn't seem as balanced as it could be.

Very true

 

[Rockingit]

That's what I was thinking:
L1 - Ground floor lighting, outdoor lighting, garage lighting, oven, kettle, toaster, dishwasher, microwave, fridge, freezer, coffee machine, warming drawer, steam oven, washing machine, tumble drier, large TV, AV equipment, hotplate, central heating pump.
L2 - 1st floor lighting, clock radio, bedroom TV, hairdryer.
L3 - 2nd floor lighting and TV in rarely used guest bedrooms.

Doesn't seem as balanced as it could be.

TBH, with this list, do you even need 3ph anyway????? A premium billed expense when all you've got is probably coped with happily on an 80A single once you've done some diversity calcs.

 

[shocking_eg]

Depends on the size of house.
It's when they want to start adding hot tubs or a swimming pool that your ****ed.

Best to over engineer than under engineer

 

[Rockingit]

Depends on the size of house.
It's when they want to start adding hot tubs or a swimming pool that your ****ed.

Best to over engineer than under engineer

to a point I agree with that - but only so far as not painting yourself into a foreseeable corner. You cannot future proof indefinitely, nor should we attempt to second guess what the needs of a customer may or may not be in five years time. If our forbears of this industry had future-proofed every installation for the next fifty years there'd be an awful lot more sparks with time on their hands now! If in the future someone decides to spend £30k or whatever to build a swimming pool, then the few hundred quid to reinstate the 3ph will form a part of that. And you, or some other spark, gets to do the job all over again. Ker-ching. In the meantime, 5 yrs of unnecessarily paying for a 3ph supply/standing charge and possibly whole-current metering will still probably be more than getting it installed when it's actually needed!