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Yet another government reverse ferret - flakey grids and property lobbies

 
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Government Schemes, Regulations, Planning & Organisations
Last Post by Transparent 7 months ago
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Transparent
 Transparent
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09/01/2025 2:20 pm  

Posted by: @johnnyb
↑

do small 3 phase units exist for sale in the UK?  Thinking about it I imagine they are needed in european countries where it is common to have 3 phases but with less amps per phase,

I'm hoping someone else can answer the first question.
I don't know the range of heat-pumps available here in UK.

Yes, you are correct that 3ph heat-pumps are much more common elsewhere in Europe.
That point was made to me last week in an email exchange with an NGED engineer.

He also pointed out an issue we haven't yet discussed here....

DNOs are concerned at what will happen to the local grid in the event of freezing fog (or similar cold weather).

All heat-pumps connected to the same local substation would most likely freeze up.
The resulting defrost cycles would likely exceed the capacity of the fuses, transformer or both.

Although we commonly have 100A Service Fuses in homes, diversification rules are such that even a new-build is unlikely to allocated as much as 10kW (42A).

So a patch of freezing fog can have a catastrophic effect on the local grid.

Just drawing the attention of @editor to the above!

 

Posted by: @majordennisbloodnok
↑

Forgive my ignorance but if one were building a new house on a new plot of land what is the difference in cost between installing single phase vs 3 phase?

This question is linked to the above point I've made about diversification.

A national housebuilder can make a considerable financial saving by appointing an Independent Distribution Network Operator (IDNO) to install the LV cabling to houses, and any new local-substation which might be required. The DNO for the area then only provides the 11kV supply (red Triflex cables below).

11kV northview

IDNOs do not necessarily stick to the same standards as the area DNO would normally apply.

The 440v 3Ph Feeds are much thinner, say 95mm² rather than 210mm²
and can be installed in trenches that are shallow.

They're OK until a couple of houses install EV chargers, and then they suffer thermal stress and burn out where there's a weak point.
Typically that's a kink in the cable, or where the outer sheath/armour was nicked by the digger when back-filling the trench.

The IDNO or their contractors are then called out to 'patch up' the damaged cable.

FeedCut

When you add in the lower cost of providing single-phase to each property, there's a significant saving to be made due to the cost of copper.

Save energy... recycle electrons!


   
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