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No three-phase for us!


We were quite keen to get three-phase because it gives us more options for AC installs and solar/battery set ups. We just got our 3-phase quote back and it came in at ~£150k lol. 🤦‍♀️

 

Annoyingly, three-phase is actually very near to our plot. The issue is that it's some kind of old set up they're not allowed to provision anymore, so they'd have to upgrade a ton of stuff. And since we don't "need" 3-phase we'd have to foot the bill for all those works.

 

Anyway, moving on!

Edited by AshleyFae

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ProDave

Posted

Just make sure you get a full 23KVA / 100A single phase supply.

 

It might be worth discussing with the electrician to do the wiring as though it were going to be 3 phase, i.e. split between 3 separate consumer units, initially fed from the single phase but would then be easy to swap to 3 phase should it ever become available.

Nickfromwales

Posted

15 minutes ago, ProDave said:

Just make sure you get a full 23KVA / 100A single phase supply.

 

It might be worth discussing with the electrician to do the wiring as though it were going to be 3 phase, i.e. split between 3 separate consumer units, initially fed from the single phase but would then be easy to swap to 3 phase should it ever become available.

You’d just install a 3ph CU, and install a 1ph conversion kit?

 

Same I’ve done a load of times, and just balance loads / phases in anticipation.

 

3ph is borderline luxury though for most UK domestic residences, and you can pull a heck of a lot of juice down a 60a/80a fuse, with 100a giving you bags of headroom in most instances; even if this is an all electric home. 
 

EV chargers will modulate to help so can be managed easily, plus @AshleyFae you can go for a hybrid inverter so the DNO only see’s the single combined output vs two AC coupled inverters (if PV + battery).

 

Export limitation can further support, plus it’s always best to plan to self consume as much as possible over each 24hr ‘solar day’.

 

All quite easily doable with some sensible advice!

Alan Ambrose

Posted (edited)

I’ve must have one of the few 3P flats in the UK. I’ve had it for ~30 years. Not a problem - but no real advantage either. Took 4 visits to get a smart meter ‘cos nobody at the DNOs handling residential can compute 3P.

 

The whole idea of the modern self-build is to keep the energy consumption down. 3P allows 2x energy consumption of 1P (usually 3 X 63A vs. 1 X 100A). Great for lumpy use of leccy and 3X the export. Also for bigger machine tools :). But you can use VFDs to solve that problem. We have some friends with a Baufritz house with 3P ovens. Lovely.

 

But in the real world…

 

p.s. if you do the calcs you’ll find you will be using on average only a few amps out of your 100A supply, less if you have a bunch of self-use PV.

Edited by Alan Ambrose
Square Feet

Posted (edited)

@AshleyFae "The issue is that it's some kind of old set up they're not allowed to provision anymore, so they'd have to upgrade a ton of stuff."

 

They always seem to say that.  It's just an excuse to get you to pay for the line to be upgraded, even if it doesn't really need it. I saw an episode of Grand Designs recently where they did that to someone who had knocked down their old place to rebuild on site. They still got hit with something like £75k for the leccy upgrade. 

Edited by Square Feet

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