3 phase electricity supply

gm0

Actual 3ph supply will exist at a site for a variety of reasons.  Which may be current or historic

- Large electric kitchen equipment
- Workshop machine tools, lathes, saws and such.

- Very large houses and domestic loads - swimming pools, multiple kitchens.
- Larger heat pumps and air conditioners
- Car chargers
- Electric heating or greenhouses and similar things. 

Some of this stuff requires 3ph connection to work.  And/or if the total at the site adds up to materially over 100A - then it is often fitted - as 3x80 (or 3xnnn).

Once 3ph exists at a site - it costs money to ask a supplier to come and switch it out to a single phase supply again - so this is often left - even if the reason to have it have sometimes gone away when a prior occupier leaves.  Filled in a swimming pool. Got rid of a workshop etc.

Normal UK 240V sockets, lights and loads can be connected to one (or more than one) of the phases via consumer units (the thing with fused "trip" switches RCD/RCBO etc) is fed from the meter.   It depends on how the place was purpose built or evolved.

Given you have a 3ph meter.  It seems likely you have a cable with 3 phases entering your house.  L1 L2 L3, N, earth.  Then distribution company fuses "rate" this supply at something - quite possibly 80A x 3 but could be more - may have labels visible.  This depends on what your cable and fuses are.  The energy retail supplier provides a 3ph meter (via a company which does that for a living).  The cables coming out the other side of the meter are where the energy suppliers responsbility for what is going on in your house ends.

So there are up to 3 live cables and a neutral coming out of the 3ph meter connected to - whatever is in your house.  Which could be one cable and two unused (now) or all 3 spread across multiple consumer units (boards of switches).  The wiring may *also* have some actual 3ph cabling distribution for all 3 of the lives to parts of your house where industrial stuff was or still is.  Nothing beyond the meter tails is anything to do with the supplier.  It's all yours.  To work on with your electricians as you see fit - to keep it safe and current and matching what you need it do.

So you need to understand what big loads you *actually* still have and may want in the future.
How much in aggregate Amps is it - and how is it all connected to the 3 phases on the incomer at the moment.

If it is a close run thing and there are no native 3 ph loads.  Then an electrician can do the relevant "diversity" calculation for you once you have established what connections are still live and which are unused can be actually permanently disconnected and discounted from the sums).  Diversity is a concept which applies rules and judgement to the maximum rated load of each protected switched circuit in adding them up - basically by assuming they aren't all at 100% 24x7

The advantage of switching to a single phase setup is that you are able to take normal domestic tariffs from pretty much any supplier.  Normal smart meter. etc.  Domestic schemes and rules will tend to apply to you as designed.  But the work to switch will cost money.  Once fiddling with electrics and retesting wiring and certifying it is mostly sensible to modernise your setup to broadly current regulations at the same time if the installation is significantly old >20-40 years plus.  Allowing "space" in what you put in - for new loads you may want to connect - car chargers, heat pumps, and for solar panel input - if you don't yet have them.

The disdvantage of switching to single phase - is that you have a lower maximum based on the house supply fuse.  Max 100A.  And if you have fossil heating and no car charger and would perhaps like to add one or both of these items at some point.  Then "how much spare capacity is available" matters to you.  3ph (all else equal) has a higher total capacity and a higher export limit for solar as well. 

So your 3x80A (or larger) 3ph supply may therefore be something to keep. 

The supplier and distribution company need to continue to provide it - for the standing charge.  And if it life expires - replace infrastructure.  Only when you ask to change it do they get an opportunity to bill you for network and cable upgrades etc. which they will delay until the last moment, or an actual fix on failure if left to their own devices.

Those of us without 3ph who would perhaps like it (for the above green energy load and solar reasons) - can be looking at £10k to £20k+ bills to have it brought to a property).  Which can be prohibitive thus driving different choices about which features to add.

It's your decision keep for current need / future use and find the "best" available 3ph tariff.  A blend of price and a supplier who deals with these types somewhat competently. 

Or you look to do electrical simplification of your house and strip out some history - cabling for a long filled in swimming pool or workshop.  Go down to a single phase - sort out the historic wiring, remove unwanted items, modernise consumer units - then make a request to change the supply over.   This will cost from one (to perhaps a couple of thousand) all in depending upon what you have and the complexity of the change over.  So the payback on it depends entirely on how much better a standing charge + unit rate combination you end up with.  And once it is gone it is gone.  The transaction to reactivate later gives the distribution company an opportunity in handling the change - to decide that that a very old buried 3ph cable of particular type is now life expired and unsuitable for activation of any new 3ph supply. Very sorry.  So you need to pay the shakedown for a new one or not have the change.

lohr500

gm0 said:

Actual 3ph supply will exist at a site for a variety of reasons.  Which may be current or historic

- Large electric kitchen equipment
- Workshop machine tools, lathes, saws and such.

- Very large houses and domestic loads - swimming pools, multiple kitchens.
- Larger heat pumps and air conditioners
- Car chargers
- Electric heating or greenhouses and similar things. 

Some of this stuff requires 3ph connection to work.  And/or if the total at the site adds up to materially over 100A - then it is often fitted - as 3x80 (or 3xnnn).

Once 3ph exists at a site - it costs money to ask a supplier to come and switch it out to a single phase supply again - so this is often left - even if the reason to have it have sometimes gone away when a prior occupier leaves.  Filled in a swimming pool. Got rid of a workshop etc.

Normal UK 240V sockets, lights and loads can be connected to one (or more than one) of the phases via consumer units (the thing with fused "trip" switches RCD/RCBO etc) is fed from the meter.   It depends on how the place was purpose built or evolved.

Given you have a 3ph meter.  It seems likely you have a cable with 3 phases entering your house.  L1 L2 L3, N, earth.  Then distribution company fuses "rate" this supply at something - quite possibly 80A x 3 but could be more - may have labels visible.  This depends on what your cable and fuses are.  The energy retail supplier provides a 3ph meter (via a company which does that for a living).  The cables coming out the other side of the meter are where the energy suppliers responsbility for what is going on in your house ends.

So there are up to 3 live cables and a neutral coming out of the 3ph meter connected to - whatever is in your house.  Which could be one cable and two unused (now) or all 3 spread across multiple consumer units (boards of switches).  The wiring may *also* have some actual 3ph cabling distribution for all 3 of the lives to parts of your house where industrial stuff was or still is.  Nothing beyond the meter tails is anything to do with the supplier.  It's all yours.  To work on with your electricians as you see fit - to keep it safe and current and matching what you need it do.

So you need to understand what big loads you *actually* still have and may want in the future.
How much in aggregate Amps is it - and how is it all connected to the 3 phases on the incomer at the moment.

If it is a close run thing and there are no native 3 ph loads.  Then an electrician can do the relevant "diversity" calculation for you once you have established what connections are still live and which are unused can be actually permanently disconnected and discounted from the sums).  Diversity is a concept which applies rules and judgement to the maximum rated load of each protected switched circuit in adding them up - basically by assuming they aren't all at 100% 24x7

The advantage of switching to a single phase setup is that you are able to take normal domestic tariffs from pretty much any supplier.  Normal smart meter. etc.  Domestic schemes and rules will tend to apply to you as designed.  But the work to switch will cost money.  Once fiddling with electrics and retesting wiring and certifying it is mostly sensible to modernise your setup to broadly current regulations at the same time if the installation is significantly old >20-40 years plus.  Allowing "space" in what you put in - for new loads you may want to connect - car chargers, heat pumps, and for solar panel input - if you don't yet have them.

The disdvantage of switching to single phase - is that you have a lower maximum based on the house supply fuse.  Max 100A.  And if you have fossil heating and no car charger and would perhaps like to add one or both of these items at some point.  Then "how much spare capacity is available" matters to you.  3ph (all else equal) has a higher total capacity and a higher export limit for solar as well. 

So your 3x80A (or larger) 3ph supply may therefore be something to keep. 

The supplier and distribution company need to continue to provide it - for the standing charge.  And if it life expires - replace infrastructure.  Only when you ask to change it do they get an opportunity to bill you for network and cable upgrades etc. which they will delay until the last moment, or an actual fix on failure if left to their own devices.

Those of us without 3ph who would perhaps like it (for the above green energy load and solar reasons) - can be looking at £10k to £20k+ bills to have it brought to a property).  Which can be prohibitive thus driving different choices about which features to add.

It's your decision keep for current need / future use and find the "best" available 3ph tariff.  A blend of price and a supplier who deals with these types somewhat competently. 

Or you look to do electrical simplification of your house and strip out some history - cabling for a long filled in swimming pool or workshop.  Go down to a single phase - sort out the historic wiring, remove unwanted items, modernise consumer units - then make a request to change the supply over.   This will cost from one (to perhaps a couple of thousand) all in depending upon what you have and the complexity of the change over.  So the payback on it depends entirely on how much better a standing charge + unit rate combination you end up with.  And once it is gone it is gone.  The transaction to reactivate later gives the distribution company an opportunity in handling the change - to decide that that a very old buried 3ph cable of particular type is now life expired and unsuitable for activation of any new 3ph supply. Very sorry.  So you need to pay the shakedown for a new one or not have the change.

All very interesting and possibly of use to the OP, but I'm not sure it answers any of his/her original questions.

Reed_Richards

lohr500 said:

gm0 said:

Actual 3ph supply will exist at a site for a variety of reasons.  Which may be current or historic

- Large electric kitchen equipment
- Workshop machine tools, lathes, saws and such.

- Very large houses and domestic loads - swimming pools, multiple kitchens.
- Larger heat pumps and air conditioners
- Car chargers
- Electric heating or greenhouses and similar things. 

Some of this stuff requires 3ph connection to work.  And/or if the total at the site adds up to materially over 100A - then it is often fitted - as 3x80 (or 3xnnn).

Once 3ph exists at a site - it costs money to ask a supplier to come and switch it out to a single phase supply again - so this is often left - even if the reason to have it have sometimes gone away when a prior occupier leaves.  Filled in a swimming pool. Got rid of a workshop etc.

Normal UK 240V sockets, lights and loads can be connected to one (or more than one) of the phases via consumer units (the thing with fused "trip" switches RCD/RCBO etc) is fed from the meter.   It depends on how the place was purpose built or evolved.

Given you have a 3ph meter.  It seems likely you have a cable with 3 phases entering your house.  L1 L2 L3, N, earth.  Then distribution company fuses "rate" this supply at something - quite possibly 80A x 3 but could be more - may have labels visible.  This depends on what your cable and fuses are.  The energy retail supplier provides a 3ph meter (via a company which does that for a living).  The cables coming out the other side of the meter are where the energy suppliers responsbility for what is going on in your house ends.

So there are up to 3 live cables and a neutral coming out of the 3ph meter connected to - whatever is in your house.  Which could be one cable and two unused (now) or all 3 spread across multiple consumer units (boards of switches).  The wiring may *also* have some actual 3ph cabling distribution for all 3 of the lives to parts of your house where industrial stuff was or still is.  Nothing beyond the meter tails is anything to do with the supplier.  It's all yours.  To work on with your electricians as you see fit - to keep it safe and current and matching what you need it do.

So you need to understand what big loads you *actually* still have and may want in the future.
How much in aggregate Amps is it - and how is it all connected to the 3 phases on the incomer at the moment.

If it is a close run thing and there are no native 3 ph loads.  Then an electrician can do the relevant "diversity" calculation for you once you have established what connections are still live and which are unused can be actually permanently disconnected and discounted from the sums).  Diversity is a concept which applies rules and judgement to the maximum rated load of each protected switched circuit in adding them up - basically by assuming they aren't all at 100% 24x7

The advantage of switching to a single phase setup is that you are able to take normal domestic tariffs from pretty much any supplier.  Normal smart meter. etc.  Domestic schemes and rules will tend to apply to you as designed.  But the work to switch will cost money.  Once fiddling with electrics and retesting wiring and certifying it is mostly sensible to modernise your setup to broadly current regulations at the same time if the installation is significantly old >20-40 years plus.  Allowing "space" in what you put in - for new loads you may want to connect - car chargers, heat pumps, and for solar panel input - if you don't yet have them.

The disdvantage of switching to single phase - is that you have a lower maximum based on the house supply fuse.  Max 100A.  And if you have fossil heating and no car charger and would perhaps like to add one or both of these items at some point.  Then "how much spare capacity is available" matters to you.  3ph (all else equal) has a higher total capacity and a higher export limit for solar as well. 

So your 3x80A (or larger) 3ph supply may therefore be something to keep. 

The supplier and distribution company need to continue to provide it - for the standing charge.  And if it life expires - replace infrastructure.  Only when you ask to change it do they get an opportunity to bill you for network and cable upgrades etc. which they will delay until the last moment, or an actual fix on failure if left to their own devices.

Those of us without 3ph who would perhaps like it (for the above green energy load and solar reasons) - can be looking at £10k to £20k+ bills to have it brought to a property).  Which can be prohibitive thus driving different choices about which features to add.

It's your decision keep for current need / future use and find the "best" available 3ph tariff.  A blend of price and a supplier who deals with these types somewhat competently. 

Or you look to do electrical simplification of your house and strip out some history - cabling for a long filled in swimming pool or workshop.  Go down to a single phase - sort out the historic wiring, remove unwanted items, modernise consumer units - then make a request to change the supply over.   This will cost from one (to perhaps a couple of thousand) all in depending upon what you have and the complexity of the change over.  So the payback on it depends entirely on how much better a standing charge + unit rate combination you end up with.  And once it is gone it is gone.  The transaction to reactivate later gives the distribution company an opportunity in handling the change - to decide that that a very old buried 3ph cable of particular type is now life expired and unsuitable for activation of any new 3ph supply. Very sorry.  So you need to pay the shakedown for a new one or not have the change.

All very interesting and possibly of use to the OP, but I'm not sure it answers any of his/her original questions.

I disagree.  Surely the observation that each phase will have its own consumer unit should help the OP to sort out how many phases are actually in use.  

QrizB

Reed_Richards said:

I disagree.  Surely the observation that each phase will have its own consumer unit should help the OP to sort out how many phases are actually in use.  

Maybe when we get the photo of the meter and any associated switchgear that Netexporter asked for in the very first reply on this thread, everything will become clear?

lohr500

QrizB said:

Reed_Richards said:

I disagree.  Surely the observation that each phase will have its own consumer unit should help the OP to sort out how many phases are actually in use.  

Maybe when we get the photo of the meter and any associated switchgear that Netexporter asked for in the very first reply on this thread, everything will become clear?

Agree. I'm not at our sailing club today, but I could take a photo of the two consumer units we have which contain a combination of single and three phase circuit breakers in each consumer unit. The single phase circuits are labelled with L1, L2 or L3 to indicate which phase they are wired to. The three phase breakers are also labelled with L1, L2 and L3 to show which phase is connected to which segment of the three bank breaker.

Granted this is in more of a commercial setting, but we don't have a separate consumer unit for each phase. Our single meter allows us to scroll through the consumption on each phase.

A photo of the OPs meter and wiring should help in trying to answer the original question. With a bit of luck we might be able to find some instructions on how to interrogate the meter's display.

Ectophile

FreeBear said:

UncleK said: It certainly sounds tosh that they "cannot fit a smart meter to a three phase supply".

Only a handful of installers will be trained on fitting three phase meters. So it is far more likely that they don't have a trained installer on their domestic team. Could also be a lack of three phase meters as well..

How much extra training does it take to shove an extra two live wires into a meter, and connect the extra two meter tails coming out?

QrizB

Ectophile said:

FreeBear said:

UncleK said: It certainly sounds tosh that they "cannot fit a smart meter to a three phase supply".

Only a handful of installers will be trained on fitting three phase meters. So it is far more likely that they don't have a trained installer on their domestic team. Could also be a lack of three phase meters as well..

How much extra training does it take to shove an extra two live wires into a meter, and connect the extra two meter tails coming out?

Don't forget you have to pull two more fuses first, then put them back afterwards.

Now it's beginning to sound more complicated!

JSHarris

This sounds like a bit of a distorted story, with input from people within suppliers that know nothing about three phase supplies (not at all surprising, IMHO, as suppliers often have near-zero technical knowledge - they are just sales people).  

Every three phase supply I've seen/worked on has had metering that measures true kVA on all three phases, and accumulates real energy in the total energy register(s).  The idea that any three phase supply could only measure one phase and then assume that the other two will be the same is pure myth.

Some older three phase supplies had three meters, one for each phase, but for at least 40 to 50 years we've had integrating three phase meters that sum the real energy usage (normally in kVA rather than kWh).

As mentioned earlier, a photo would quickly sort this out.

DrH2

Sorry for delay, new to forum and how to post a pic. Appreciate all the comments.

QrizB

Thank you for the photo.

The operating manual for the Elster A1100 meter is here:

https://www.rayleigh.com/media/uploads/A1100-Operating-Manual.pdf

As far as I can tell, the meter displays the total electricity use for all three phases. The electrician who told you o triple the redings may have been incorrect.

Exactly what readings have you been submitting to your electricity supplier? How have they been using them wehen billing you?