3 phase head in a single phase meter Uk energy networks saying I'm not 3 phase

[Lucien Nunes]

This sounds like a storm in a teacup. YOU don't have a 3 phase supply because YOU don't own the head, the DNO does. It's up to the them what they can supply you with, as Darkwood says even if all three phases are present there might be other single-phase consumers using all the available capacity on the ones you aren't.

Your description of the test 'The sparky tested all cables at the head each measuring 100 amp each' does not make sense electrically, so you might have confused the results. In any case that test involves tampering with equipment that is not yours and is possibly an offence to gain access inside.

If your supply is taken from an older network, there are various possibilities as to why what might first appear as a 3-phase service cable is actually not. Hence, possibly, the mismatch between your neutral connection and the phase markers.

 

[Risteard]

How on earth can each wire be pulling 100 Amps when there is only one fuse in use

Exactly what I was asking earlier!

 

[Risteard]

testing at 400V (although again this value does seem unlikely, you would expect it to be a little more)

Nothing unlikely about it at all as throughout CENELEC countries this is known as a 400/230V supply, so 400v is the correct designation of that voltage.

 

[Darkwood]

he measured across and just to be clear again the supply cable is a 3 phase one the main head is a 3 phase head the feeds are all live at 100amp each 400v but for some reason keep being told its a single phase even the quote states to disconnect a single phase to upgrade to a 3 phase supply EVEN I HAVE 3 PHASE HERE... the only single phase thing is the meter

The link Snowhead kindly provided explains what a bunched cable is, it clearly states that it has to be replaced because it is a bunched cable, basically the spare cores have been used to double up the cores in use to possible reduce the overall resistance.
Quoted from the link:-

Any alterations to networks including bunched conductor installations shall make provision for the restoration of a conventional network solution.

Their own regulation means it has to be replaced

I too don't understand what you say your electrician is confirming, like has been said it is very confusing from an electrical point of view, your pic shows the cutout is sealed so he has no way of testing with meters what you have in there, regardless of it been a 3ph head, I don't think you are in anyway been over charged or having work done that isn't neccessary and going at them with little subject knowledge is only going to create waves and cause you delays and problems, that's if they don't just turn around and say forget it then.

 

[snowhead]

A potential cost saving idea might be to ask your energy supplier, not UKPN for a 3 phase meter, which you'll have to have anyway and Customer side 3 phase isolator.

Before they install it they'll have to confirm with UKPN that the supply is 3 phase and can be used.

Once the meter is in, assuming it can be, apply to UKPN to have the supply relocated.

 

[HappyHippyDad]

Nothing unlikely about it at all as throughout CENELEC countries this is known as a 400/230V supply, so 400v is the correct designation of that voltage.

I realise its the 'correct' voltage, but how often do you measure a single phase supply and it is 230? It is usually more as we seem to be a 230V country on paper only, so i am assuming most 3 phase supplies are still 415V.

 

[Risteard]

I realise its the 'correct' voltage, but how often do you measure a single phase supply and it is 230?

Actually here, frequently. It has always been 230V here as the south was traditionally 220V and Britain traditionally 240V.

Regardless, 400V and 230V are the only correct way to describe those voltages. It is a nominal voltage - voltage fluctuates all the time. So as long as it is within the range of +10%/-6% then that is what it is.

 

[davesparks]

Nothing unlikely about it at all as throughout CENELEC countries this is known as a 400/230V supply, so 400v is the correct designation of that voltage.

Be has stated that the voltage was measured as being 400V, also that he is within a few metres of the substation. The voltage should be a lot nearer 433 as all uk distribution transformers output 250/433 regardless of what the nominal is.

If it was measured at 400 then it suggests the substation is running at its max capacity already

 

[Risteard]

Be has stated that the voltage was measured as being 400V

But that is how the voltage measured would be described.

I wouldn't say I had measured 233V at a terminal - I would say I had measured 230V. Likewise, I wouldn't say I had measured 408V - I would say 400V.

 

[davesparks]

But that is how the voltage measured would be described.

I wouldn't say I had measured 233V at a terminal - I would say I had measured 230V. Likewise, I wouldn't say I had measured 408V - I would say 400V.

Then that would be untruthful and incorrect. A measured value is exactly that, the value which has been measured. It is different to the nominal value which is the theoretical or named value.

 

[davesparks]

I realise its the 'correct' voltage, but how often do you measure a single phase supply and it is 230? It is usually more as we seem to be a 230V country on paper only, so i am assuming most 3 phase supplies are still 415V.

It is not correct, it is nominal, that is to say it is the voltage which has been named as the theoretical value.
The actual voltage which all public network distribution transformers in the UK output is 250/433V, this is a material fact which will not change.

 

[Risteard]

Then that would be untruthful and incorrect. A measured value is exactly that, the value which has been measured. It is different to the nominal value which is the theoretical or named value.

No, because the voltage must be recorded as the nominal value. So by measuring 400V that is anywhere between +10% to -6%. It is still 400V and should be described as such.

The measurement is merely to confirm that there is 400V there, and not to see whereabouts it is within the accepted tolerance for that nominal voltage.

Meters have an accuracy within a certain percentage too so who is to say how accurate your reading is?

 

[davesparks]

No, because the voltage must be recorded as the nominal value. So by measuring 400V that is anywhere between +10% to -6%. It is still 400V and should be described as such.

The measurement is merely to confirm that there is 400V there, and not to see whereabouts it is within the accepted tolerance for that nominal voltage.

Meters have an accuracy within a certain percentage too so who is to say how accurate your reading is?

That is a ridiculously blinkered approach.
This is supposed to be a technical trade and electricians should be able to understand the basic scientific principles behind it.
If you are reporting a measured value then it must be the value which was measured, if you are reporting a nominal value then it should be the nominal value.

 

[Risteard]

That is a ridiculously blinkered approach.
This is supposed to be a technical trade and electricians should be able to understand the basic scientific principles behind it.
If you are reporting a measured value then it must be the value which was measured, if you are reporting a nominal value then it should be the nominal value.

All he asked for someone to check was whether he had a three-phase supply, i.e. 400V between phases.

Why on earth would it be relevant what the precise meter reading is (and notwithstanding the fact that a meter reading has an inherent inaccuracy anyway)?