3-Phase 415V supply. How many circuits?!?

[factualchimp]

Hi! I have recently changed my job and my employer has asked me to survey the existing electrical system. The main incomer is 100A 415V 3-phase and neutral and each phase and neutral is attached to a separate CU. This is how is breaks down:-

L1+N= (100A CU) Handdriers in toilets, lighting circuit, emergency lighting in toilets, 1 ring main 5 sockets.
L2+N= (100A CU) 7 fluorescent light circuits (4 on each circuit), and a couple of ring mains (5 sockets on each)
L3+N= (100A CU) 5 ring mains (5 sockets on each circuit)

The sockets will be rarely used and definitely not all at the same time.

However, I need to install ANOTHER CU about 30 meters from the Main incomer which will power a 16kW PA system(not sure on the loading though),an electric shower, ring main and lighting and im not sure how to go about connecting it all in as obviously all of the phases are being used. Could I parrallel the SWA off the phase and neutral with the least circuits or would you suggest a complete revamp with all of the gear above shared between two phases and a separate CU installed for the PA system, shower, ring main etc?

The only problem I would have with replacing the existing CU's is that the tails on the circuits would all have to be crimped and im not sure whether im completely happy with that.

Sorry its so much to take in but any help would be awesome!!!

Thanks very much!

Steve

 

[UNG]

Not sure what you trying to do but normally the load should be balanced equally across all three phases if possible. If all the existing single phase boards are grouped together I would consider installing a three phase DB and connect the existing circuits to this and also the new sub main this would allow you to balance the load better across the phases

 

[mogga]

Exactly Ung also mind balancing specialy with showers taking a heafty load Id also find out what will be getting plugged in and try n spread circuits for rings

 

[factualchimp]

Thanks for the quick replys guys. Ive been dumped in at the deep end a bit so im just trying to figure out what is going on. I was going to see if I could consolidate the 3 existing CU's into 2 new ones across two of the phases (this would free up a single phase) and then add an extra CU for the new circuit onto the free phase. does that sound like a viable option? obviously balancing where possible.
Thanks
Steve

 

[UNG]

It could be an option but I think you would still be better with a TP&N board as you can fit an MCB to the board for the sub main it would also provide a single point of isolation for the premises

 

[bugsy]

Either install new tpn D.B. as suggested or MCCB panel board. this would alow you to split up the phases without touching the existing C.U.'s

 

[factualchimp]

Nice one! Yeah thats a good idea. Thanks very much for your help, much appreciated. There may be more questions from where that came in time!Cheers, Steve