DIY 3 phase power distro

[grimslater]

Hi, I run a small pa system hire company,
we've started to do gigs with generators and theatres which supply primarily 63A 3 phase power on red Ceeforms.
What is the cheapest way of legally converting that into several 13amp sockets?

 

[ban-all-sheds]

Probably by using a qualified electrician.

 

[slup]

Link
Another link

 

[davelx]

and of course, Rubber Box

http://www.rubberbox.co.uk/on-the-shelf/index.php

 

[ericmark]

If 5 pin you can have a distribution unit made quite cheap. Think Clipsal make them. It houses trips and splits phases. Some also include device to test the neutral is present.

If 4 pin you need a transformer and will cost more.

 

[stuartsjg]

You need to bear in mind that you need to keep the phases balanced. If its, say a 30kVA Generator then this is 10kVA per phase.

Ive seen transformers and generators go pop due to heavily unbalanced phased.

What is the total load of your PA and lighting?

Its probable that the generator is over spec... ive seen 125kVA generators hired out for not much more than a few floods and a few 100w's of PA system. Total load would be well under 5kW!

Stuart

 

[plugwash]

Afaict distribution units of this scale are generally custom built, if you don't know exactly what you are doing I would get an electrician to do it for you. Most likely a 63A 3-phase supply will not be RCD protected so you will need to provide RCD protection in your unit somehow.

here is how I would do it assuming it's going to be used indoors (outdoors similar principle but you would need an IP rated CU enclosure and masterseal sockets)

Get an CU enclosure with 12 modules of total space.
Mount the enclosure, the 63A inlet and 24 13A single sockets (doubles are risky in an environment like this) on some kind of board
Remove the bussbar if the CU enclosure comes with one. At one end of the CU enclosure fit a four pole isolator. then fit 8 three phase 32A RCBOs.

I would then wire
The inlet socket to the feed side of the isolator using 16mm
Each live on the load side of the isolator to the feed side of the RCBOS (two RCBOs per phase) with 16mm
The neutral on the isolator to the neutral bar with the cabling supplied in the CU (probablly 16mm)
The rcbos neutrals to the neutral bar with thier supplied tails.
The sockets in groups of four to the RCBO outputs with 6mm in a radial configuration.
Earths all to the CUs earth bar.

 

[ColJack]

not too good at maths are we?

8x3 = 24 +4 pole isolator = 27 modules of width..

and you suggested a 12 module board?

last I looked, 27>12 no?

I take it you meant single phase RCBO's? which would make 12, but would be unevenly ballanced.. ( you'd have 3 on 2 of the phases, and 2 on another.. )

 

[conny]

cheapest way

As a business shouldn't you be saying, 'Safest way'?
You do have a duty of care above everything else after all.

 

[grimslater]

Could I......

Wire up a 63A 3 phase plug to 32A 3 phase Ceeform socket ( I will not be pulling more than 32A per phase).

Then use a 32A 3 phase Ceeform inlet wired to a CU with 3 32A RCBOs (one on each phase) which then would go to 3 single phase 32A Ceeforms.

I'd then use 4 way 13A power extensions with 32A Ceeforms on to get my power.

This would ensure when I got to a venue, I would be able to power my equipment if they had either 32A single phase, 32A 3 phase or 63A 3phase?

 

[plugwash]

yes I would use single phase RCBOs, afaict three phase RCBOs are rare expensive and for this application would be pointless (you want to keep the number of things on one RCD down)

sorry my figures were off, I must have been half asleep when I wrote it, here is a corrected version (changes in bold)

Get an CU enclosure with 10 modules of total space.
Mount the enclosure, the 63A inlet and 24 13A single sockets (doubles are risky in an environment like this) on some kind of board
Remove the bussbar if the CU enclosure comes with one. At one end of the CU enclosure fit a four pole isolator. then fit 6 single phase 32A RCBOs.

I would then wire
The inlet socket to the feed side of the isolator using 16mm
Each live on the load side of the isolator to the feed side of the RCBOS (two RCBOs per phase) with 16mm
The neutral on the isolator to the neutral bar with the cabling supplied in the CU (probablly 16mm)
The rcbos neutrals to the neutral bar with thier supplied tails.
The sockets in groups of four to the RCBO outputs with 6mm in a radial configuration.
Earths all to the CUs earth bar.

edit: finally got it right

 

[tim west]

Could I......

Wire up a 63A 3 phase plug to 32A 3 phase Ceeform socket ( I will not be pulling more than 32A per phase).

Its not so much what load you are putting on it but during a fault the cabling out of the 32A ceeform will be backed up by the 63A breaker. You may find you are banned from using such kit at venues, especially if "house electricians" ask to inspect it.

 

[Spark123]

If you are trying to plan for all eventuallities then you can do the opposite - make a 32A plug to a 63A socket jumper. You just have to remember you don't then have 63A to play about with from the 63A outlet - label it up as such.
Stick with the 63A plug on the distro.

 

[ColJack]

Get an CU enclosure with 10 modules of total space.
Mount the enclosure, the 63A inlet and 24 13A single sockets (doubles are risky in an environment like this) on some kind of board
Remove the bussbar if the CU enclosure comes with one. At one end of the CU enclosure fit a four pole isolator. then fit 6 three phase 32A RCBOs.

3X6 is still 18

Single phase RCBO's is what you want...


ready made, and raring to go..

one of these and 3-6 of these..

or they do bespoke, so if you ask for a 63A 3 phase inlet, with 12 x 13A outlets ( 6 x 32A DP RCBO's ) then I,m sure they can accomodate..
better than making your own.. and probably quite a bit slammer too since you won't have a seperate CU enclosure, and no back boxes for the sockets...

in fact I've taken the liberty to request a quote for the above.. I'll let you know..

I've found another site that sells the rubberbox stuff.. it's expensive.. but probably cheaper direct..

 

[ColJack]

pricing it up individually is just as expensive by the looks though..



[code:1]WYNSBS32/1 32 Amp 30mA RCBO Single Module SP - Wylex £22.65 ea. 135.90
WYWS123 125A TP Switch Disconnector £15.75 ea. 15.75
WYNHTN4 4 Way 125 Amp TP&N Distribution Board £75.00 ea. 75.00
MKK080 13 Amp 1 Gang Single Unswitched Socket - White £2.65 ea. 31.80
MKK2200 1 Gang Metal Frame For Panel Mounting £1.90 ea. 22.80
June Extra Discount Discount £ 3.90
SubTotal £ 277.35
VAT £ 41.60
You save £ 268.60 (49%) on Normal Trade Prices! Total £ 318.95
[/code:1]

and that's not including the 63A inlet and enclosure to hold the sockets..