Three Phase Supply for New build House

[equitum]

Scenario:

3 Storey, 6 Bedrooms, 5 bathrooms, double garage


A lighting consultant has provisioned 150 luminairs,

I anticipate in region of 75 socket/FCU outlets, 6 showers and all the usual requirements such as extractors, cooker cct etc.

I'm to provide a desktop quoute from the plans provided by the lighting design consultant...

Initial thoughts indicate 20 circuits spread over three consumer units, one per each floor, say 10 way split load with spares.

I need to do calcs on diversity and maximum load but surely single phase PME 100A supply will be pushed ? Anyone designed a similar size newbuild? My estimate for accessories total £6000 ! (luminaires 3K alone!)

 

[Lectrician]

You dont indicate any lumionaire wattage, so have nothing to even guess at!

If the 6 showes are elec (very rare for new build!), then even a TP supply would be well loaded if everyone showered together, but....seperately!

Diversity is your bag to calculate and anticipate - get the balance correct between the OSG, what you know and the total possible load.

 

[equitum]

His "Consultant" hasn't specified the wattage, (whats he paying for, you might ask!)other than a percentage being part L low energy and some pretty pictures and plans, lets assume 35W average per luminaire erring on the high side. Plumber hasn't quoted/havent got the heating/plumbing design so quite rightly may not be all or any showers may be electric but again looking at worse case. The problem is being asked to give a quote and the client not really having thought about it properly, so will need to part design/specifya solution.

He is receiving a quote from the builder to supply plumbing and electrical installations, but as he is a friend I would at least like to give him an idea of what should be realistic figure, not one which sounds cheap but will not be an adequate/futureproof solution or actually the price he will end up paying !

 

[JohnD]

humorous post removed as equitum doesn't like it

 

[plugwash]

If there is more than one electric shower or any electric heating then you will almost certainly need a three phase supply.

If all heating/showers/hot water is gas then i'd imagine a normal domestic supply will cover it but it will be a bit stretched.

 

[equitum]

Dear Mr. Architect: blah blah blah

Did you actually bother to type this out ?

Please explain the point of this rambling, and any constructive part this plays in answering my post. I was interested in what experience others had of such properties and previous designs thereof. If this is the wrong forum I have misjudged the site.

If you think my post is irrelavent, feel free to state your opinion. Yes, it is vague, but so is the criteria I am furnished with to provide an estimate.

Plugwash, thanks for your reply.

 

[equitum]

ps. If new large houses do not have multiple electric showers then I assume they have multiple boilers. The cost comparison between a quote for one against the other is useful, I would have thought.

 

[breezer]

you can have as many electric showeres as you like on single phase, reason is you can only use one at a time becuse of water flow / pressure from mains.

go and ask in plumbing what they they suggest for multiple showers

 

[equitum]

you can have as many electric showeres as you like on single phase, reason is you can only use one at a time becuse of water flow / pressure from mains.

I an 6 bed house (big family) not unreasonable to expect three showers in use at one time or attempted despite water main pressure, if they were all 10.5Kw thats a nice (theoretical) load of 137A, mommy pops on the iron and kettle, dishwasher and cooker to bake the bread for brecky....all of a sudden its all gone dark !

 

[ricicle]

Yes, it is vague, but so is the criteria I am furnished with to provide an estimate.

DIY?

 

[Lectrician]

you can have as many electric showeres as you like on single phase, reason is you can only use one at a time becuse of water flow / pressure from mains.

go and ask in plumbing what they they suggest for multiple showers

Just as you can have a larger lecky supply, you can have a larger water supply too

I have worked in a hotel in the sticks with no mains gas - 9 lecky showers - no idea on water, but the lecky supply was 250amp TP - mainly due to the kitchen loading.

 

[FatGit]

ps. If new large houses do not have multiple electric showers then I assume they have multiple boilers. The cost comparison between a quote for one against the other is useful, I would have thought.

The parents have two power showers in their house. It has an extra-large hot water cylinder, heated by gas.
I'd imagine that larger properties would have very large or multiple cylinders.

 

[JohnD]

I was in a large place in Australia where each bathroom had its own hot water cylinder (I think they also used solar to heat them) so no-one could be short of hot water due to another person hogging it all.

 

[Adam_151]

I have worked in a hotel in the sticks with no mains gas - 9 lecky showers - no idea on water, but the lecky supply was 250amp TP - mainly due to the kitchen loading.

I'm sure someone on the IEE forum posted about a guest house that had eight 8.5kw ones on a 100A SP service.... its amazing what actually works in the real world (although I'm assuming the kitchen must have been gas)

 

[securespark]

Yes, it is vague, but so is the criteria I am furnished with to provide an estimate.

Then you need to firm up a few things before you can go ahead with it...