3 phase db question

[nabby68]

My mother in law has purchased an old sunbed shop to convert into a craft centre. It had no gas to the property so heating it will be electric. It has a 3phase supply which was needed for the sunbeds. I have disconnected all the wiring for the sunbeds. One phase is feeding a consumer unit consisting of 2 ring mains and 3 radials.
I plan to install 3 x 3kw convector heaters each on 20a radials. Can I use one of the phases to do this directly or should I take a tail off one of the phases to instal a 3way consumer unit for the heating?
Many thanks

 

[JohnW2]

... It has a 3phase supply which was needed for the sunbeds. I have disconnected all the wiring for the sunbeds. One phase is feeding a consumer unit consisting of 2 ring mains and 3 radials. ... I plan to install 3 x 3kw convector heaters each on 20a radials. Can I use one of the phases to do this directly or should I take a tail off one of the phases to instal a 3way consumer unit for the heating?

You will obviously need some sort of CU/DB to accommodate the 20A MCBs (and probably an RCD) (or three 20A RCBOs) for the three new radial circuits. This is not really DIY work, particularly since, as sounds to be the case, this is a commercial property.

Kind Regards, John

 

[plugwash]

Normally with a 3 phase setup you would have a three phase DB from which you can take both single and three phase circuits.

Do you have such a DB? if not how were the sunbeds supplied? can you provide a photo of the setup?

 

[FDJ]

I suppose one obvious question would be:
Could you save money by converting to a single phase supply?
Frank

 

[nabby68]

Thanks for all your replies.

There is a 3 phase db. That is how the sunbeds where originally supplied. So I guess I can provide a picture but would be at a later date.

 

[nabby68]

I suppose one obvious question would be:
Could you save money by converting to a single phase supply?
Frank

I suppose this essentially what I'm asking aswell

 

[ban-all-sheds]

This is not really DIY work, particularly since, as sounds to be the case, this is a commercial property.

Nabby - you must consider this issue.

There will be liability insurances to be taken out, and these may well have clauses requiring that the electrical work be done by a qualified person.

There is H&S legislation which applies, such as the Electricity At Work Regulations.

 

[nabby68]

This is not really DIY work, particularly since, as sounds to be the case, this is a commercial property.

Nabby - you must consider this issue.

There will be liability insurances to be taken out, and these may well have clauses requiring that the electrical work be done by a qualified person.

There is H&S legislation which applies, such as the Electricity At Work Regulations.

Point taken. Thank you

 

[nabby68]

Normally with a 3 phase setup you would have a three phase DB from which you can take both single and three phase circuits.

This seems the way to go?

 

[JohnW2]

I suppose one obvious question would be: Could you save money by converting to a single phase supply?

I suspect that the answer is probably 'no', since it doesn't appear to be the case with domestic supplies. I have a 3-phase supply to my house, but am paying exactly the same (both 'standing charge' and electricity cost) as our neighbours with the same supplier who have single-phase supplies. Indeed, when I look at my tariff options on my supplier's website (E.ON), it makes no distinction between 1-phase and 3-phase (domestic) supplies.

Kind Regards, John

 

[nabby68]

Normally with a 3 phase setup you would have a three phase DB from which you can take both single and three phase circuits.

So, I'm ok to take 3 single circuits from one phase on the db?

 

[phatboy]

Normally with a 3 phase setup you would have a three phase DB from which you can take both single and three phase circuits.

So, I'm ok to take 3 single circuits from one phase on the db?

No, but the electrician is.

 

[flameport]

So, I'm ok to take 3 single circuits from one phase on the db?

Why this fixation with connecting everything to a single phase?

If there is a 3 phase DB already there, then connect the new circuits to it. That's what it's for.
It's generally advisable to distribute the circuits and loads equally between the phases.

If there is a 3p board, then the 'consumer unit' isn't required and probably shouldn't have been fitted in the first place.

It's doubtful that '3 x 3kw convector heaters' is appropriate heating for a shop, and they certainly don't require a 20A radial circuit for each one.

 

[JohnW2]

So, I'm ok to take 3 single circuits from one phase on the db?

Why this fixation with connecting everything to a single phase? If there is a 3 phase DB already there, then connect the new circuits to it. That's what it's for. It's generally advisable to distribute the circuits and loads equally between the phases.

Indeed - but, to be fair, I think the OP's proposal was to use one of the other phases (other than that apparently currently feeding a single-phase CU) for the three heaters - not that that would represent much of a sharing across phases.

Kind Regards, John

 

[scousespark]

You need to get an electrician to do this. As pointed out, there are contractual issues as well as legislation (HSE, insurance and the propery lease) covering the commercial entity. This is not a diy job.