Kevonius

Hello
I wondered if you could help?
I’m only domestic installer and have been asked about the following
There is a 3 phase 200A metered supply into a factory unit. From the meter it goes straight into a pull handle isolator with fuses for each phase (old Colours). All wiring from that point has been removed.
Some offices are being built inside the unit and need to be supplied with single phase power like within a domestic property with the following
1 x Ring Main Office
1 x Ring Main Kitchen/Hallway/meeting room (no Oven)
1 x Light circuit (Fluorescence)
1 x Light circuit (Security)
1 x Alarm Circuit
1 x Radial Circuit (Hand Driers)
1 x Radial CCTV

Then they need 3 Phase power to the workshop(not all M/C running at the same time)
3 x 64A Points for M/C
6 x 32A Points for M/C
5 x 16A Points for M/C
8 x Double sockets (220V)

My question is should I use a 17th Edition Consumer unit for the office area taken from 1 of the phases or should I use a 3 phase consumer unit to balance the phases?

I have minimal 3 phase experience, so not sure what to do on the 3 phase side, can I use a high current carrying capacity cable for each phase + N & E (like a radial circuit) & drop this to each of the 14 x 3 phase points around the workshop and fit breakers at these points (this means they would be in series like spurs) or put the breakers on a ring main type circuit with a 100A breaker at the CCU

Thanks for your help

WarrenG

If you have little experience of three phase, try and find out more about what is required as this will have an effect on your over all installation.

For example do you require any contactors for switching high loads?
Any timers required?
How long will the equipment be running for?
What are the start up currents likely to be?
When will the equipment be run?
Whats the location of each M/C?

Etc,etc

At least then you can assess the bigger picture. Balancing loads and pin pointing any future potential future problems is all catered for at the design stage.

Personally I would be looking to supply a number of 3P distribution boards, dependant on the maximum demands of the system and divided into sub-mains around the workshop. By doing this you could cater for expansion (i.e. any extra machines) and minimize any disruption when faults occur.

Again a small 3P board could be used seperately for the office block which would cater for any further added circuits and aid with better balancing of the overall system load.

In my experience, offices and factories are always adding / removing circuits over the years. A better design will cater for the potential extra's.

Hope this helps!

The better you map it out the cleaner the system will be.