Chnaging house back from three phase

[brianj42]

Hi All

We have just bought a house that is currently three phase electrics and connected via a pole sat slap bang in the middle of the back garden.

The house was originally fed from the pole at the front of the house but I "presume" upgraded to 3 phase as it became a restaurant.

Changing it back to a house we want to now relocate the feed back from the rear to the front.

Luckily, the house was completely rebuilt in 2003 following a huge fire so the electrics are all brand new and a cracking fuse box all well laid out.

As far as I can see, the only three phase socket in the whole house was for the commercial dishwasher.

There are three cables in from the pole, one meter, to the junction box.

Basically, is it an easy task to convert back ?

 

[Taylortwocities]

It is a job for your local friendly DNO. They are the only ones who can undertake this work.

You don't say where in the UK you are. This link will help you contact the right people http://www.nationalgrid.com/uk/Electricity/AboutElectricity/DistributionCompanies/

If you are going to do the job, you might like to consider providing a trench and have the lekky arrive underground. Perhaps the pole can be then disposed of. But you'll need a site survey from the DNO.

PS I hope you have deep pockets!

 

[leeco]

I would just keep the 3 phase as I can't see what you are going to gain by going on 1 phase.

 

[ericmark]

In properties I have seen where it was a three phase supply like old churches all they have done is remove two fuses and seal the supply has remained as it was.

The problem is 2008 new rules came in so although rules in 2003 are modern likely there will be a lack of RCD protection or the protection will be 100ma rather than 30ma.

So rather than just linking the three phases together likely you will need some alterations to the consumer unit. Likely simply replacing the MCB with RCBO but there will be some cost involved.

To change the entry point into the property we have seen reported on here some really large figures. Only person who can tell you is the DNO but be sitting down when you ask.

 

[JohnW2]

As you’ve been told, only your DNO can move the supply, and it’s likely to be pretty expensive. As TTC said, it’s certainly worth discussing with them the possibility (and relative cost) of moving it underground. If the new supply point/meter is an appreciable distance from your distribution board/consumer unit/’fuse box’, you would need an electrician to arrange the extended connection, with a fuse near to the meter to protect the cables.

As has been mentioned, it’s worth considering/discussing (with DNO and your electrician) whether you actually want to revert to single-phase (as well as having the supply point moved) – since you never know what future requirements you may have, and we don’t even know what your present requirements are (I presume from what you say that it’s a fairly large house). Particularly if they took an underground route, I doubt that it would cost appreciably less than keeping 3-phase (if that's what you have). Your electrician could advise you regarding your likely total electricity requirements. The actual ‘running costs’ need not be any more for 3-phase – my house has a 3-phase supply, and I’m on exactly the same tariff as I would be for a single-phase one.

As for your electrical installation itself, if, as you say, there is only one 3-phase circuit connected to it, then there would not necessarily be much work required on your installation as a result of the 3-phase to 1-phase change - the 3-phase socket circuit would obviously have to be removed, and all three ‘phases’ could be fed from the new single-supply, but that may well be all. However, as eric has pointed out, if the building was rewired in 2003, there may well be issues (particularly in relation to RCD protection) to be addressed if one wanted to bring the installation up to current standards – the easiest way of achieving that may, or may not, be to get a new Consumer Unit (‘fuse box’) fitted. These would all be issues to discuss with your electrician.

There are three cables in from the pole, one meter, to the junction box.

I would expect there to be four cables (three phases plus neutral). Is that not the case? If you only have three supply cables, it can't really be 3-phase supply (it could be something often called 'split-phase', which is essentially '2-phase') - but that doesn't really alter anything that anyone has said.

Kind Regards, John

 

[brianj42]

Thanks guys, this is appreciated.

There are 5 cables coming across in fact, but two are thinner and I thought they may have been supporting wires.

I have read up on Western Powers (My supplier) "moving your power" leaflet and will arrange for them to have a survey.

But, and only hypothetically, can I do this ?

As only the ground floor is the business and the upper floors are classed as domestic residence by the council.

1: Cable from the fusebox to the front of the house via an electrican

2: Put a new meterbox on the front of the house

3: Dig a trench to the "old" supply pole which is still there in the front corner of the garden on my land

4: Apply for a "new" domestic supply from the old pole

5: Connect the whole fusebox to the meter

Two additional questions

1: Who physically connects the tails from the fusebox to the meter, the DNO, the electric suppler, or the electrician ?

2: Can I position the meter box away from the house nearer to the pole and run my own feed to the house, as there is a large stone boundary wall next to the pole ? Does it have to be on the house ?

 

[JohnW2]

I have read up on Western Powers (My supplier) "moving your power" leaflet and will arrange for them to have a survey. ... But, and only hypothetically, can I do this ?

Almost 'anything' is theoretically possible (at a price), but you'd really need to discuss this with the DNO, since it depends on so many factors (e.g. what is connected to, or could be connected to, the 'old supply pole'. I would have thought that (depending on the various factors) what you describe might be possible.

As only the ground floor is the business and the upper floors are classed as domestic residence by the council.

I don't fully understand the significance/point of that statement. Is the residential/commercial split going to remain? Are you talking about a single new supply for the whole of the property?

1: Who physically connects the tails from the fusebox to the meter, the DNO, the electric suppler, or the electrician ?

Three people are likely to be involved - the DNO, the 'meter operator' and your electrician - the three would need to liaise.

2: Can I position the meter box away from the house nearer to the pole and run my own feed to the house, as there is a large stone boundary wall next to the pole ? Does it have to be on the house ?

To have the supply/meter remote from the house is not impossible. That's something else to discuss with the DNO.

Sorry not to be more useful, but we're trying to determine the length of a piece of string, about which only the DNO will know very much! In the final analysis, cost might be a major factor in choosing between various options. If you are prepared to dig trenches etc., that might help to reduce costs a bit.

Kind Regards, John

 

[Taylortwocities]

My two pennyworth re having the meter remote from the house....

The supply company (DNO) is responsible up to and including the meter. Anything after that is down to you to supply and maintain.

The supply that the DNO provides will meet ESQCR (THE ELECTRICITY SAFETY, QUALITY AND CONTINUITY REGULATIONS)

This includes the quality of the supply and essential things like the Earth Fault Loop Impedance. This is an important figure as it will determine that your fuses will blow if there is a fault!

If you add a long length of cable on your side of the meter then the EFLI becomes increasingly difficult to achieve so you'll need heavier and heavier cable the further the distance is.

Personally I would want the DNO to take the risk for as much as possible and keep the connection from the meter to the consumer unit short.

 

[brianj42]

Cheers for that John, time to get Western Power out and discuss options.

Its an ex restaurant that is not going to be a business, subject to current planning app. The two upper floors are residential apartments but in a strange twist they are all fed from one meter/supply/box on the ground floor.

So, we plan to turn the one business/2 apartments back into a single residence, hence getting shot of the 3 phase and its back garden eyesore pole, and restoring it to the original supply which is at the front.

Interesting conversation with Opus this morning asking them to change the meter from commercial to domestic, but got there eventually.....

 

[JohnW2]

Cheers for that John, time to get Western Power out and discuss options. Its an ex restaurant that is not going to be a business, subject to current planning app. The two upper floors are residential apartments but in a strange twist they are all fed from one meter/supply/box on the ground floor. So, we plan to turn the one business/2 apartments back into a single residence ...

Fair enough.

... hence getting shot of the 3 phase and its back garden eyesore pole, and restoring it to the original supply which is at the front.

As I said before, I think it might be worthwhile for you to at least discuss with your electrician and the DNO, the possible value (and relative cost) of retaining a 3-phase supply. As for 'getting rid of the eyesore and restoring it to the original supply at the front', I can't help but think there must have been some reason (cost?) why the supply was previously moved from front to back - so I'll be interested to hear what the DNO have to say about that.

Kind Regards, John

 

[JohnW2]

My two pennyworth re having the meter remote from the house....This includes the quality of the supply and essential things like the Earth Fault Loop Impedance. This is an important figure as it will determine that your fuses will blow if there is a fault! ... If you add a long length of cable on your side of the meter then the EFLI becomes increasingly difficult to achieve so you'll need heavier and heavier cable the further the distance is. ... Personally I would want the DNO to take the risk for as much as possible and keep the connection from the meter to the consumer unit short.

Obviously a valid conceptual point. However, given the fairly modest size of service cables which DNOs often use (and are allowed to use, per their regulations and practices) there is obviously the potential to get a better (i.e. lower) EFLI by maximising the distance from meter to CU - by using sufficiently 'heavy' cable. For example, with a single-phase TN-C-S supply, I would imagine that (probably 3-core) 25mm² SWA from meter to CU would probably 'beat' the situation which would exist if the DNO's head and meter were moved (quite probably using 16mm² cable) closer to the CU, wouldn't it?

Kind Regards, John

 

[brianj42]

I think, so it would appear, the original front supply is single phase when it was a small country pub that served a few locals. Upgraded later to a larger pub and restaurant they changed it to 3 phase and the easiest routing to place was over the back.

I would love to keep it 3 phase but the cables and pole are smack bang in the middle of the back garden and moving the 3 phase to the front would cost a fortune which is why I suppose it wasn't done that way in the first place.

What advantage do I have as a residence of 3 phase over single ?

PS: Contacted Western Power and they are dispatching Warack and Ajax to advise.....

They also said I could have the outside meter box next to the pole at the front of the garden and trench/cable to the fusebox myself...... Taking your advice TTC into account

 

[JohnW2]

I think, so it would appear, the original front supply is single phase when it was a small country pub that served a few locals. Upgraded later to a larger pub and restaurant they changed it to 3 phase and the easiest routing to place was over the back. I would love to keep it 3 phase but the cables and pole are smack bang in the middle of the back garden and moving the 3 phase to the front would cost a fortune which is why I suppose it wasn't done that way in the first place.

Fair enough. Do I take it that the pole at the back only supplies your property? Were you prepared to keep the pole there, there should be the opportunity to take the 3-phase supply from there, underground, to anywhere you wanted.

What advantage do I have as a residence of 3 phase over single ?

Possibly none! The most obvious difference it that it potentially offers three times as much electricity - so it depends a lot on your (present and possibly future) electricity needs for what sounds like quite a substantial house. A 3-phase supply obviously offers the opportunity to supply 3-phase loads should you ever need them. I suppose another consideration is what a subsequent occupier might want to do with the building. There are other small advantages. I have a 3-phase supply to my large residential property, roughly arranged as one phase per floor, so I can lose one phase (whether due to a selective 'power cut', loss of one DNO fuse or whatever) without losing all my electriity.

Kind Regards, John

 

[brianj42]

John, unfortunately the pole and its cable are smack bang central and look rather butt ugly. If I could go underground from the transformer all the way then no problem but its transformer to pole to me. I should think the neighbours would be glad to see the back of theses ugly cables too.

 

[JohnW2]

John, unfortunately the pole and its cable are smack bang central and look rather butt ugly. If I could go underground from the transformer all the way then no problem but its transformer to pole to me. I should think the neighbours would be glad to see the back of theses ugly cables too.

Fair enough. Where is the transformer (I presume not on your land?)? ... and, as I asked before, do I take it that this pole serves only your property?

Kind Regards, John