3 phase domestic installation

[Chri5]

I viewed a job this week.

The head was 3 phase and all are live. Only 1 phase is metered and the other 2 phases are not connected to anything (there's no tails from the DNO heads to metering).

Client needs new radial and there's spare ways on the CU which has the neutral / live tails from the DNO head via the meter.

Just want to check that the site is within regs and that I can continue to offer a price for the work. Client has been in house for just 12 months and is a normal demand situation. Previous occupier had a workshop which has been knocked down and there are remnants of a 10mm SWA that 3 core that might have been the reason for the initial 3 phase installation.

So current setup is:

Only 1 phase metered 9although all 3 appear live at head
The 1 phase is connected to a 12w split Wylex CU
All live client services feed only from the above CU
All bonding, main and equipotential is current standard

Sorry if the question appears dumb, but haven't seen a 3 phase site, with all phases live and only one being used before

 

[Spark123]

So in reality it is a single phase supply, just 3 phase on the DNO side to the head? I wouldn't worry about it tbh.

 

[toasty]

I don't see that as a problem, my house (and my parents) are exactly the same, I even have all 3 fuses in place, just only one of them is in use.

 

[Chri5]

It's just that all 3 phases have power and I have always expected that when 3 phase was 'on' that the load of the house MUST be balanced across all 3 phases.

So there's no need to go out hunting for 3 phase CU and getting the DNO to meter / provide tails?

The house is a standard 3 bed semi and demand is for no more than average use.

 

[Spark123]

In a large industrial installation it is better to ballance the phases, in a domestic it won't matter that much. The DNO attempt to ballance the phases by, in a street having say house 1 on red phase, house 2 on yellow, house 3 on blue. (forgetting the harmonization!!)
The DNO has only provided you with a single phase supply by the sounds of it, just take that as a normal single phase supply.

 

[Sarahspark]

It's just that all 3 phases have power and I have always expected that when 3 phase was 'on' that the load of the house MUST be balanced across all 3 phases.

' Have power 'is not quite the right terminology.All 3 phases are live would be better as the other 2 are not supplying current (and are not set up to) and thus the installation can be treated as single phase

regards Sarah

 

[kai]

When was the requirement (if any) that domestic properties were fed with three phase supply feeds abolished?

Quite a number of older properties were fitted with a 3 phase incomer.

My 1960's three bedroom terraced house however only has a single phase incomer feed (but has gas central heating).

 

[Spark123]

No problem with 3 phase to a domestic premises, just in this case it is there but two of the phases are not used and disconnected by the DNO.

 

[Lectrician]

It is common for the last house on street to have a TP head - they just take the end of the cable into the house and terminate rather than jointing outside.

No problem having the head there and only using one phase - I bet the other two phases have NEVER been used.

If the DNO wanted you to use them, they would have provided three phase metering wouldn't they

An ensuthiastic person could make use of the three phase for a workshop etc, but it would be rare to see this, as the cost of three phase DB's and submains/final circuits compared to single phase would make it an expensive way to go compared to buying SP machines.