3 Phase.

[ady1966]

Good morning, I have purchased a 3 phase steamer oven for my small carp bait business and I am in the middle of refitting the workshop. I have been contemplating whether to convert to single phase, by some kind of inverter but it turns out I have a 3 phase connection to  my property after all ! Fantastic ! The oven is 9kw with 3 elements. What I would like some advice on is once the electric company have installed a new meter which they are doing free of charge , could I have a separate fused connection to the oven socket or would I need to replace my existing fuse box ? Any help would be appreciated.

 

[Andy™]

single phase loads need to be reasonably balanced between all 3 phases, so you would need a new 3 phase board to do this

 

[apprentice87]

What existing other stuff are you running there??

john..

 

[ady1966]

A 3 bedroomed bungalow with workshop. In the workshop there are a number of single phase motors and equipment. At the moment, a single phase goes to the fuse board (RCB) and then on to the various supplies. British gas are going to fit a 3 phase meter. I only have 1 3 phase oven at the moment, so only need one spur.

 

[ady1966]

 

[Lurch]

single phase loads need to be reasonably balanced between all 3 phases, so you would need a new 3 phase board to do this

Steady on, that's a bit of a blanket statement that doesn't apply in a lot of cases. There's no need to split up a few small circuits just because.

A 3 bedroomed bungalow with workshop. In the workshop there are a number of single phase motors and equipment. At the moment, a single phase goes to the fuse board (RCB) and then on to the various supplies. British gas are going to fit a 3 phase meter. I only have 1 3 phase oven at the moment, so only need one spur.

There is no such thing as an RCB, you probably mean MCB.

Is the workshop detached from the house? You wouldn't necessarily need a new distribution board in the workshop but there are 2 ways of doing this. Either just run a supply out for the machine and leave everything else as it is or run a slightly larger supply out and fit a new distribution board in the workshop. Obviously the latter will be more expensive, but I would get yourself a quote for each option and weigh up the pros and cons, like if you fit a new board then in the future you could use other 3 phase machines without too much hassle.

 

[Andy™]

you really are lucky to have a TP supply there. if you didnt, it would cost ££££ to put one in

 

[apprentice87]

I do not understand.... The OP will have to have a TP board [of sorts] somewhere, he cannot just stick the feed to the oven thing into the new meter terminals..

Unless he can arrange for the new board to be within 3 meters of the new meter [and hence feed it direct from the new tails] he is going to have to install a submain complete with OCPD and stick the DB on the end of that.

john..

 

[Tony S]

It would be cheaper if the steamer could be converted to SPh.

I wonder why British Gas will do the work for free, could it possibly be something to do with a higher standing charge?

 

[Andy™]

It would be cheaper if the steamer could be converted to SPh.

I wonder why British Gas will do the work for free, could it possibly be something to do with a higher standing charge?

had similar thing a few years ago (commercial unit though). SP meter installed but TP service head. they changed meter FOC. standing charge was slightly higher iirc but not by much, unit rate was the same

 

[ady1966]

Hi, thanks for your replys ! I would like to connect new meter to existing MCB and run a large spur from it to feed the steamer which is only  4meter cable run from the board. I know I will need to connect that spur to a fused socket.

 

[Andy™]

you cannot connect or take a TP supply from the board you have to a 'spur' (it will be a new radial circuit, your terminology is wrong) to supply your new equipment. you will need the new TP supply either feeding a new TP board which will cover everything including the new circuit for the steamer, or (not as good) split the tails, leave existing and fit a switch fuse to supply new circuit. either way, neither options are really a DIY job

 

[apprentice87]

Hi, thanks for your replys ! I would like to connect new meter to existing MCB and run a large spur from it to feed the steamer which is only  4meter cable run from the board. I know I will need to connect that spur to a fused socket.

This is simply NOT POSSIBLE.

Firstly, you need to understand that a single phase "fuse box" as you put it, is COMPLETELY different to a three phase one, so what you want to do is simply not possible..

Secondly, you need to understand that you, or any electrician, WILL NOT [you absolutely need to understand this] be connecting the new meter to ANYTHING, that is not how it works.

Now, do you know what meter tails are?? They are the thick grey cables in your photo that connect the fuse box to the meter. There are two of them yes??? Now, when they fit the new meter, there will be four of them instead. The longest you are allowed to have these meter tails is three meters, so, it follows, that realistically, [unless you want to install a "submain", and trust me, you do not, [more £££] the new "fuse box" CANNOT be any further than about  2 or 2.5 meters from the new meter.

How it works is this;

Firstly you need to get an electrician to come along and install you a separate three phase "fuse box" Then they could connect a short run of cable to a three phase socket for you if that is what you want.

The electrician will install the meter tails to your new "fuse box" and leave them dangling loose at the ends that connect to the meter.

Then, the electric company will then come along and fit the new meter to your new meter tails, PROVIDED that is, that ONE, they like the look of what they see, TWO the tails are not longer than three meters, THREE they are shown a completed EIC [it is a certificate the electrician will give you]

If they are not happy with all three, they will simply refuse to fit the meter and send you a hefty bill for their time...

john..

 

[Adam W]

Maybe you're getting your terminology confused but that isn't going to work:

The existing consumer unit you have (the cream coloured bank of switches) is single phase, so it only has the capacity to connect one live to.  To run this 3 phase steamer oven you will need to connect all 3 phases from the new meter to a new 3 phase distribution board with a 3 phase circuit breaker for the steamer oven.   You could then either transfer the circuits from that MK consumer unit to the new distribution board (neater but may prove more expensive if you need to buy new RCBOs) or keep it as it is and run a submain from the new distribution board.

I'm not sure what you mean by connecting a spur to a fused socket.

 

[ProDave]

I would fit s small 3 phase board, say a 4 way one. With a bit of shifting around I would bet it would fit where that number plate is.  Have the tails from that ready to connect into the meter.

Fit a 3 phase mcb for the socket for the steamer. Feed the bungalow from one phase via the new 3 phase board, and the workshop from another phase.

This can all be fitted, tested and certified before the meter man gets there, and phase 1 and 2 tails (feeding the bungalow and workshop) temporarily connected with a henley block to the single phase meter to keep it running until meter swap day.

 

[Andy™]

and when you do go looking for a sparky, get one who knows 3 phase / commercial, many domestic 'electricians' do not know anything about 3 phase

 

[apprentice87]

As Andy said!!!

john..

 

[ady1966]

Thanks everyone for your help  - simply trying to project manage the situation. Will get a qualified electrician with 3 phase knowledge to deal.

 

[Lurch]

I do not understand.... The OP will have to have a TP board [of sorts] somewhere, he cannot just stick the feed to the oven thing into the new meter terminals..

Unless he can arrange for the new board to be within 3 meters of the new meter [and hence feed it direct from the new tails] he is going to have to install a submain complete with OCPD and stick the DB on the end of that.

I was thinking 2 options;

1. Leave everything as it is but simply add a 3 phase switch fuse at the meter position and run the supply to the steamer from there. Easiest and cheapest.

2. Fit a larger switch fuse and run a new supply to the workshop and replace the workshop consumer unit with a 3 phase distribution board. More work and more expensive.

 

[apprentice87]

Yes, i think either would be fine. I would definitely go for option 2 though, it would be far better..

To be honest, i think the OP was hoping to do it himself... I suspect he thinks you have to connect the 3 phases together and then cram them into where he plans to remove the single tail from the CU .. Good luck with that one!!

john..