UK 3 Phase Supply

[mikehenson]

I have recently become involved with our local church when I became aware that the installation was 3 phase.

Looking at the meter I see that phase 1 is using 60%, phase 2 using 48% and phase 3 zero.

I was always under the impression that 3 phase supplies should be balanced?

 

[James]

Looking at the meter I see that phase 1 is using 60%, phase 2 using 48% and phase 3 zero.

I was always under the impression that 3 phase supplies should be balanced?

Ideally the phases would be roughly equal in current draw.
However, it only really becomes an issue when you are running out of capacity on one phase.
I am concerned that you might be reading the meter wrong.
It is not possible to draw 60% on phase 1 48% on phase 2 and 0% on phase 3
It adds up to 108% of your total load.

 

[Jock from the north]

I have recently become involved with our local church when I became aware that the installation was 3 phase.

Looking at the meter I see that phase 1 is using 60%, phase 2 using 48% and phase 3 zero.

I was always under the impression that 3 phase supplies should be balanced?

It also becomes an issue with current being diverted thru the neutral if the phases are extremely unbalanced .the neutral conductor would have to be suitably sized in that instance .it is a real challenge to balance a 3 phase installation especially when single phase loads are concerned and how and when they are being used .is there multiple distribution boards in church .

 

[Flanders]

Just a thought is phase 3 supplying storage heaters that only run over night

 

[James]

It also becomes an issue with current being diverted thru the neutral if the phases are extremely unbalanced .the neutral conductor would have to be suitably sized in that instance .it is a real challenge to balance a 3 phase installation especially when single phase loads are concerned and how and when they are being used .is there multiple distribution boards in church .

I was trying to keep it relevant, I have never seen a distribution circuit below 1Mwatt that has a reduced size N conductor.
Mostly but I can’t say always, N is the same size as the live conductors unless it is not there at all.

 

[Jock from the north]

Just a thought is phase 3 supplying storage heaters that only run over night

Yeh this is the problem.the designer might try there best to balance the phases /loads but if certain equipment say heaters are switched off or not being used you have the issue of unbalanced loads .there maybe parts of the building where the heaters are never on due to rooms not getting used .

 

[Jock from the north]

I was trying to keep it relevant, I have never seen a distribution circuit below 1Mwatt that has a reduced size N conductor.
Mostly but I can’t say always, N is the same size as the live conductors unless it is not there at all.

I completely agree .