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Hi guys, if a 3 phase board is to be installed, with 250A mains. With 8 32A 3 phase sockets, 8 single phase 16A sockets, 2 light circuits and 3 phase 63A socket on it, that exceeds the 250A. I understand you would have to consider diversity factor etc into it but is that still too much or would you intall 2 boards and seperate some of the circuits. What is the formula for working out 3 phase diversity factor etc.
 
Hi guys, if a 3 phase board is to be installed, with 250A mains. With 8 32A 3 phase sockets, 8 single phase 16A sockets, 2 light circuits and 3 phase 63A socket on it, that exceeds the 250A. I understand you would have to consider diversity factor etc into it but is that still too much or would you intall 2 boards and seperate some of the circuits. What is the formula for working out 3 phase diversity factor etc.
What's size are the service head fuses
 
What's size are the service head fuses
Its fed from a 300 amp isolator. Also sorry if this is a stupid question, but Blue 16 amp sockets can I put them on a radial or ring together? Or would it be best on seperate circuits as if one goes down incase of a fault they still have others. Also not wanting to overload anything so I think best seperate but would there be an issue if on same circuit?
 
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What is the formula for working out 3 phase diversity factor etc.
There is not, to my knowledge, any set rule for this (unlike domestic cooker, etc).

Really you need to go through all of the likely equipment that could be attached and work out the typical peak and running currents, and the likely percentage of time being used. Also if any are mutually exclusive e.g. one 63A load but 5 sockets it might be plugged in to is still only 63A on the DB (unless they buy another).

If there is a real risk of the incomers being blown you ought to consider means of stopping that. So either some priority switching for loads to stop too much, or even just having a MCCB incomer set to be selective with the fuses so they can reset without skill (and not having to ask the DNO to replace fuses!).
 
What is the formula for working out 3 phase diversity

You need to know the application and design intention, because the purposes to which 16A ad 32A sockets are put can vary widely. E.g. in an entertainment venue, every 32A socket might be fully loaded at once with 32A of lighting, totalling 250A, whereas in a small engineering workshop there might be eight 32A sockets for convenience of positioning but only one machine using 18A moved from one socket to another.

Simulpost with @pc1966

Blue 16 amp sockets can I put them on a radial or ring together

A ring would not be a normal configuration because there's no reason to assume the load will be spread out as on a 32A ring with 13A sockets. The max permitted OCPD is 20A. How many sockets you can put on a 20A radial again depends on the usage. We have some circuits with multiple sockets that are permanently used for machines that use around 3-5A each, so even running three machines on one circuit is fine. For three ovens taking 16A each the circuit would be completely useless.
 
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Also sorry if this is a stupid question, but Blue 16 amp sockets can I put them on a radial or ring together?
It depends on how they might be used.

16A sockets have no fuses themselves, so they have to be protected by 16A OCPD. Thus putting several sockets on to a single circut means 16A total load. If that fits with the possible use-case then fine (say multiple places for one appliance, or they are needed for mechanical means but loads are actually well below 16A), but in most cases they are separate radials.
 
Oh ok, so the 3 phase and single phase sockets would be used for weld sets, i did think they would have to be run on separate radials the 16s but just wanted to double check. I know not all sockets will be used at the same time but just unsure on the 250A incomer. As I dont want to exceed that.
 

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