DIY 3 phase power distro

got the quote back from rubberbox..

63A 3P+N+E inlet, phase neons, 6 x 32A 30mA DP RCBO's, 12 socket outlets ( 2 per breaker ) all in a nice 185H box, £440.00 +VAT + P&P
can do you a PDF of the quote, but can't host it..
 
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2 13A sockets on each 32A breaker? Surely you would be better with 3 sockets or a lower rated breaker?

Colin C
 
It doesn't really matter as you are limited to 13A from a standard plugtop.
If there's enough sockets then it should hopefully make people steer away from using unfused adaptors.
 
yes but assuming that he might want to use 13A from both sockets, that's 26A, the next size breaker is the 32A..
 
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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.

Plugwash, could you elaborate why doubles are risky, please
 
Plugwash, could you elaborate why doubles are risky, please
I suspect that the answer might be in the immediately preceding post ...
yes but assuming that he might want to use 13A from both sockets, that's 26A ....
... which could precipitate yet another re-run of the debate about the rating/capabilities/whatever of double sockets!

Kind Regards, John
 
24 13A single sockets (doubles are risky in an environment like this) on some kind of board

Sorry john, should have quoted more, it was more concerning the mention of environment, do you think he means the likely hood of high loads then.
 
IIRC BS1363 sockets are only required to be tested at 20A total and the general consensus here seems to be that running them at 26A is not a good idea. Worse a 13A fuse doesn't blow the instant someone goes over 13A.

That's not so much of a problem in most domestic or commercial settings (which is presumablly why the test in BS1363 is the way it is), it's rare to see long duration high power loads in close proximity to each other and if the electrical installation is fit for purpose then use of long extension leads should be minimal.

OTOH when you are dealing with a situation where everything is powered through extension leads from a few (or even just one) distribution points and where there are likely to be quite a few heavy loads around the risk of two 13A sockets next to each other both being loaded to 13A or more at the same time becomes much greater. For this reason I do not think double sockets are appropriate for that environment.
 
Sorry john, should have quoted more, it was more concerning the mention of environment, do you think he means the likely hood of high loads then.
Indeed. As he has now confirmed, (and perhaps I also should have been clearer) I assumed he was thinking that 2 x 13A loads on a double socket (which, give or take 'the debate', many/most feel is 'too much') would be more likely in the sort of environment being talked about than in a domestic/commercial one.

Kind Regards, John
 
IIRC BS1363 sockets are only required to be tested at 20A total and the general consensus here seems to be that running them at 26A is not a good idea. Worse a 13A fuse doesn't blow the instant someone goes over 13A.
Indeed, and as per recent discussion about the characteristics of BS1362 fuses, not only will "a 13A fuse not blow the instant someone goes over 13A" but it will probably not ever blow unless the current is over about 21A - so a double socket could theoretically end up carrying around 42A indefinitely (and greater currents than that for appreciable periods) without any fuses blowing (if someone inappropriately/incorrectly used 13A plugs/fuses for loads >13A).

Kind Regards, John
 
Since this was started in 2009 I would hope it has been all done and dusted by now.

I have said before in theroy a 5 pin socket should have a neutral but in practice I have found many without a neutral so splitting the phases also needs a
product_71560_200.jpg
detection device of some type.

I remember back in 1980 working in Algeria we had container type cabins which had three rooms each room had one phase from the three phase supply from a line of 32 amp sockets laid out ready for the cabins to arrive.

Theory was great and 99% of the time it worked but every so often the neutral would get a bad connection the AC would survive but lights would blow and also any thing the worker had plugged in.
 
Since this was started in 2009 I would hope it has been all done and dusted by now.
I'm sure it will have been, but it's rocky's current interest in these distribution boxes (see his new thread) which caused him to raise a question about something which was written in this very old one.
I remember back in 1980 working in Algeria we had container type cabins which had three rooms each room had one phase from the three phase supply from a line of 32 amp sockets laid out ready for the cabins to arrive. ... Theory was great and 99% of the time it worked but every so often the neutral would get a bad connection the AC would survive but lights would blow and also any thing the worker had plugged in.
Can you explain that to me? Each of the cabins would presumably be supplied with one phase and N. If the N failed, or even just became high resistance, they would presumably just lose (or suffer a deterioration in) their supply - not experience any high voltages (which only exist between phases)? Perhaps I'm missing something, but I'm not aware of any situation which can result in an abnormally high pd between a phase and neutral (or even between phase and earth).

Kind Regards, John
 
I too had a lost N at a DB, there was single phase sockets on each phase.
When someone plugged in to say RED phase, the RED phase current went via the appliance down the neutral, as it had nowhere to go it went via the neutral bar, and back up to any other socket neutrals,
If something was plugged in say YELLOW phase, again the YELLOW phase current went via the appliance, and having NO neutral, technically shorted the two appliances in series across RED and YELLOW phases.
It was a conference room and blew up a few laptop chargers and a projecter apparently, a tester between L an N at the socket, showed about 400v i recall
 
I too had a lost N at a DB, there was single phase sockets on each phase. ... When someone plugged in to say RED phase, the RED phase current went via the appliance down the neutral, as it had nowhere to go it went via the neutral bar, and back up to any other socket neutrals, ... If something was plugged in say YELLOW phase, again the YELLOW phase current went via the appliance, and having NO neutral, technically shorted the two appliances in series across RED and YELLOW phases. ... It was a conference room and blew up a few laptop chargers and a projecter ...
I suppose that could do harm (result in excessive voltages across some loads) if the loads on the RED and YELLOW phases were substantially different. As you say, in that situation the two loads would be in series between the RED and YELLOW phases - in which case, if the loads were equal, they would presumably both see about 200V between their Phase and 'neutral'.

Kind Regards, John
 

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