3 phase

How do you install 3 phase into a domestic household?

At great expense!

If you want a proper TPN installation, you will need to speak to your local electrical supply authority.

The alternative is to use either a rotary convertor or a 230-415 invertor.

What are you looking at powering?

Cost me £15,000 to have it all laid on, buried cable down to workshop et al. Say 20 yards road to house then 30 yards house to workshop. Maybe 60 all told counting run through house. Then finding an electrician actually able and willing to connect it all up defeated me so 7 years on its still dead.

4 guys quoted, "yeah we can do it and never came back"!

At least it cured my RCD and MCB issues. Original feed was damaged and not safe! As I'd know for 40 years and utility ignored.

Clive.

Harry

Great offer, thanks. I'm in East Sussex.

Clive.

Typically in the UK, you don't. It's not impossible but - unless you can show you're going to buy a lot of electricity over several years - the cost is usually prohibitive. It's because the cost of wiring up is usually recovered over several years of big bills, and, because domestic users rarely consume enough power to make that economic, they get walloped with the full up front cost. As a single-phase house might be some distance from a 3-phase source, you might find yourself paying for trenches and poles as well as a the cabling. The second problem is one of safety. You don't want single phase domestic equipment running on different phases in close proximity. Also, most electricians wouldn't touch it.

These days there are many inexpensive electronic boxes t hat convert ordinary 240V single-phase into 3-phase specifically to drive 3-phase machines like lathes. VFDs start at about £60 for 2.5HP on ebay. Would one or several of those solve your requirement? Even largish workshops use them rather than plumb in real 3-phase.

Dave

Clive PM sent
H

Errr, that wasn't my experience.

I simply rang the local electricity board and they said they'd send a man out to do a survey. I asked where the nearest 3-phase was, as if it's half a mile away you pay for the whole length so no point getting a quote. But no, they said they'd send a man anyway. Turns out the nearest 3-phase is buried the other side of the road. They quoted £2500 to supply the 3-phase. I understand from a friend in the house building industry that about £1000 of that is for digging up the road. If a utility digs up the road they have to repair the work FOC if needed, for up to a year after the work is done. So given the sub-sub-contractors they employ they whack the price up. No questions were asked about usage or anything else. I just confirmed that the 3-phase meter wouldn't have a wobbly if only one phase was being used. I also checked that I would pay the domestic standing charge and pence per unit.

Having 3-phase makes life easy. All the control gear works and I can run two speed motors without any issues, including on the fly switching. The horizontal mill has a 4/5hp Dahlander motor and that's no problem either on proper 3-phase.

Andrew

Did you have to run the pipe/duct from your house to the edge of the property or did they do that bit as well?

Edited By Mark Rand on 19/10/2018 18:24:46

I've put three phase into two properties. The last one was in the late 80's. The three phase supply runs up the road and is 6ft - 7ft below ground level. It runs just inside my property line. I was able to dig a trench across my lawn and under the drive and then tunnel under the garage/house foundations. I dug a 6ft x 6ft x 7ft down to the three phase cable to expose it. I was doing this in mid October, digging by floodlight every night after I got home from work. Had lots of funny comments from people when they realised there was someone down the hole digging. All they saw was heap of soil flying out of a hole.Laid a heavy plastic duct (supplied by the Electricity Board) and then fed the three phase cable through it. Ran it up wall to Meter Location and put up my own Distribution Board. Ran a Single Phase to my house Distribution Board. The Electricity Board turned up, terminated cable at Meter, I put the tails into my Distribution Board and they then cut open the three phase cable and soldered the new cable to the main feeder. All done with it live. IIRC it cost me around £500. The previous one was at my Dad's house for our lathes and milling machines, I did all the same work and it cost even less.

A friend of mine has just had the same thing done but he had to have a JCB a the nearest 3-phase was in a field about 100 yards away. Cost him a little more.

Colin

Hi Michael, my experience was similar to Andrew's. Called the power distribution company who sent over someone to do a survey and prepare a quotation. The nearest 3 phase supply was in the centre of the road outside my house. Power company quoted to dig up the road, connect into the live 3 phase line, and run a 3 phase cable across the road and over to my garage, about 30 to 40 yards. I had to dig the trench (3ft deep) on my property and drill a hole through garage wall. They did it for less than GBP2000. A separate power supplier company then connected a meter (at no cost) and arranged the power contract with me. I then got an industrial 3 phase experienced electrician to wire up a distribution board and some supply lines to two machines. Job done.

Gareth

Shame I don't need three phase as its six feet from the house and runs along the gardens of all the houses in our Crescent, My builder found it when his digger brought up a busted gas main to my house whilst doing some work for me, don't break a gas pipe it costs £800 to join to ends back together

Martin P

Hi John, I have two motors on the lathe and four on the mill (one of the lathe motors is two speed). At the end of the day I've just connected each machine up and have not had to change any of the installed electrical control systems. Electrical or instrumentation is not my engineering discipline.

My post was intended to provide further information to the original poster to say that having 3 phase installed could be a feasible option.

Regards,

Gareth

Edited to include 2 speed information

Edited By Gareth Jones 9 on 19/10/2018 20:55:29

The quote stated I would need to dig the trench on my property and install ducting. I couldn't get any sense out of the electricity board about exactly what I needed to do, so I ignored it. The digging team dug down to the cable on the road verge, dug a 4ft long trench my side of the road, another 4ft trench on my drive and a hole by the garage to get to the J pipe. They then moled between the holes and trenches to fit the cable. No ducting was used.

Andrew

In the context of computer room equipment, I'm sure I read that the requirement to keep single phase equipment on different phases well apart had been dropped. The chances of a phase-to-phase fault, or touching both phases at the same time, are minimal.

As noted elsewhere, a commercial/industrial electrician should be happy to work on 3-phase. I accept that, by number, most electricians may well be domestic.

For real fun, consider what happens when you lose the neutral on a 3-phase supply powering an unbalanced load of single phase equipment. It is usually expensive.

Just a comment.

Utilities usually keep the phase loads reasonably balanced by connecting three houses with each one wired in sequence to each of the three phases.

Probably, they would not not be too happy to put in a 3 phase supply and then have one phase more heavily loaded that the others.

Howard

Contrary to some of the negative posts, you can get a quote for 3 phase by contacting your electricity distribution network operator (DNO). The cost will depend on the location of the nearest suitable 3 phase main cable and the supply capacity you want . If you don't know who your DNO is, you can find out at this website:

**LINK**

Regarding your own internal wiring, a commercial/industrial electrician will be able to quote for the necessary work.

Stuart

Hi Howard, I live in a residential street and when western power connected my three phase supply no mention was made of any concern to balance loads between ajoining residences.

Regards,

Gareth