3phase to 240v

[ziggy1979]

Hi Everyone

It's been a while since I visited the forum and hope you are all well (and also that I'm posting in the right place).

I am trying to open a new gym and have found premises. Before we get an electrician to quote for what we need I'd like to have a basic understanding of what may be needed as budgets are tight (as always!).

There is 3 phase power coming into the premises. All existing internal electrics up to the distribution board will be taken out by the builder and all new wiring will be installed.

We need electrics mainly for

1. up to 20 treadmills which need a dedicated 240v 16amp line per treadmill
2. Up to 10 steppers as above.
3. Sockets around the gym floor for hoovers, etc
4. Power for AC, fire alarm, etc.
5. Power to an office for computers, CCTV power, etc etc and
6. Lighting

The main thing I don't get about 3 phase power is if we can run all of those things directly off the distribution board or whether we run wires from the distribution board to 240v CUs like we have at home and then power everything from these units. Also, if that's the case, how many CUs can u have off the distribution board and how many treadmills, etc could each CU handle?

Sorry for the long waffle just trying to get my head around what I should expect to be quoted for. Thanks for all your help,

Z...

 

[BigJon]

I would imagine a 3 phase board would be installed and all your circuits will be spread across the 3 phases.

 

[RF Lighting]

You can run single phase items from a 3 phase board.

Depending on how big the building is, and where the circuits are required, it may be best to install an additional board, but this really isn't something we can really give too much info on without physically seeing the job.

It sounds like you're going to have a fairly well loaded installation. It would be well worth getting your electrician on board now to ensure the incomming supply is big enough for your requirements.

 

[333rocky333]

3 phase boards generally are 36 ways with a mainswitch rated at about 100 amp per phase built in
so you get 36 single phase circuits, or 12 three phase circuits or a combination of both

You can get larger boards but if you lose the board supply you will lose most of the gym.

its quite normal to have two or more of these boards fed off a common busbar chamber

We do fitness first and see more than three 36 way boards in one room sometimes.
there showers and changing rooms alone use about ten 3 phase ways to heat the water tanks

 

[RF Lighting]

I'm not sure that's quite correct. I see TP boards of all sizes. I don't think 36 way is the standard size.

As for busbar chambers, which decade are you installing in?

 

[333rocky333]

I don't think 36 way is the standard size.

Id say its the most common, to cope with the proposed ways he needs.

google it
24 way, 36 way 48 way 72way see for yourself

 

[ziggy1979]

Hi and thanks for your replies.

Using the 36 way board as an example, does that mean that 20 treadmills would use up 20 single phases leaving 16 for other things like lights, etc.

Also, can't I have 1 single phase going to a 240v CU which then has 4 treadmills on dedicated supplies each with 16A mcbs and so only use 5 phases for the 20 treadmills (ie 5 CUs each powering 4 treadmills)

Also, to have more than one 3 phase board, do I need to have more than one 3 phase supply coming in?

Thanks again!

 

[333rocky333]

Hi and thanks for your replies.

Using the 36 way board as an example, does that mean that 20 treadmills would use up 20 single phases leaving 16 for other things like lights, etc.

yes but as a rough quide your limited to about 100amp per phase
7 treadmills per phase might use a bulk of that
As rf says you may need a bigger supply to the premises

Also, can't I have 1 single phase going to a 240v CU which then has 4 treadmills on dedicated supplies each with 16A mcbs and so only use 5 phases for the 20 treadmills (ie 5 CUs each powering 4 treadmills)

you can but if one went wrong you would most likely take out the CU supply also and lose 4 machines, you will also still need to balance these CUs across the 3 phases, you could always fit a 48 way or bigger board to give you more ways.

If the treadmills are a long way from the Main board then your Cu option located nearer the machines may be a good idea

Also, to have more than one 3 phase board, do I need to have more than one 3 phase supply coming in?

No, but it has too be big enough for your assessed load,
as Rf said a bigger boards available if you want all wired back to that location, but sometimes a sub main is run to a second board located elsewhere, so as too minimise wiring to the machines etc, similar to what you said about the CUs
How the electrician connects them all to your one supply is down to his preference,

seems Rf thinks busbars are old hat so lets see how he would connect Two 3 phase boards to a single supply

 

[conny]

You mention 3 phase supply but don't state if there is a neutral facility.
To obtain 230V you will need a neutral supply as well. Your electrician will need to design an installation that balances the load across all three phases.
As suggested, get him on board as soon as possible.

 

[333rocky333]

You mention 3 phase supply but don't state if there is a neutral facility.
.

electrics up to the distribution board will be taken out by the builder and all new wiring will be installed.

Unlesss they had candles its safe to say its Three phase and Neutral

 

[conny]

Fair comment.

 

[Lectrician]

I see 4, 6, 8, 12 way TPN boards all the time. 12 way is certainly not "the norm".

Larger are available. too.

MEM do a nice range with 2 outgoing ways rated at 125amp, the remainder being the standard 63amp max, designed for running two TPN submains. This is the only thing the new MEM TPN boards have going for them!

You have one main board, with (say) a 200 amp incomer, with 12 TPN 63amp ways available, and then use this board to feed of to 2 more 125amp incomer TPN boards. 3 boards on site, and no need for a MCCB panel board or busbar chamber/switch fuses.

 

[ziggy1979]

Hi and thanks again for all your advice.

If I need more power, would that need a separate 3 phase supply or can more power be "sent" through the existing 3 way power supply ie increase A to more than 100A? (I'm guessing no, but thought I'd ask!).

Def need to get onto electrician too...and idea of ballpark £s (more to the point above what level may they be having a laugh)?

Thanks!

 

[ban-all-sheds]

Get 3-4 quotes - you'll soon know if anybody is HAL.

 

[RF Lighting]

seems Rf thinks busbars are old hat so lets see how he would connect Two 3 phase boards to a single supply

Depends on the situation. Normally for a small second board ≤63A then just submain it off the first board. >63A then use a panel board.