any opinions with this one??????

[mswesty]

hi , i normally do domestic so here goes.....

what would you do with the following?
> customer has a large Open plan factory which is approx 25m x 25m, customer intends to section off the building to make 10 smaller buisness units / outlets.

the main 3 phase incomer is new (2008) and is cpn 100Ax3

he wants aroumoured cables run to a dist board in each unit individually meterd of which 6 units will be single phase and 4 need to be 3 phase.

im thinking from service head into 3ph board then from there into each individual meter (privatly owned) then off via armoured to the units. this distribution room would then provide control for the landlord and the meters are in a secure location.

however im unable to determine maximum demand because we dont know who is going to move in!

whats youre thoughts with this one??

 

[johnboy6083]

go from 3ph head to a panelboard. you would have to find out what the likely use of the units would be, but if they are small, then im guessing that 100A per phase should be fine. from panelboard to an isolator and DB in each unit.

 

[tlangdon12]

Non-electrician replying - but I have been a specifier of TP distribution networks for commercial installations.

I'd definitely talk to the customer about delaying the selection of breakers until each tenant can confirm their power requirements.

Until/unless you have some confirmed diversity, I wouldn't overcommit the supply.

I'd also look at a pre-built metering panel like the ones shown here http://www.sinergy-meters.com/assests/22-10-09-Klik%20Installation.pdf and use meters with a resetable peak demand function as well as KWh. If the tenants requests 16A, but his peak demand is never more than 10A, when the next tenant arrives and wants 20A you know you can drop the first tenant's allocation to 10A. (You only have 16A per phase per unit to play with - 3 x 16A in the Three Phase units, so you customer should offer each tenant 16A to start with and see it they can live within that budget.)

I'd also wire all the units for Three Phase power and TP metering to give maximum flexibility - unfortunately this will be at the maximum cost, but will give the most flexiblity and avoid signficant changes in the future.

 

[con-site guide]

Well sounds like 100A is max, so allow for each unit 100A

 

[tlangdon12]

I don't think you need to provde cables capable of carrying 100A to all units; there must be some diversity, you just don't know what it is yet. Cables rated to 50A should be sufficient for 99.99% of the possible combinations of tenants. It doesn't sound like the units are big enough to pull 50A, if there is a only 100A TP supply to 10 units.

You can always double up a cable if there is a tenant who wants 100A TP and the landlord wants to give it to them.

Let us know what you do!

T

 

[Darkwood]

Its a large building with regards to heating, is there a gas supply into building this needs to be taken into account, if not then demand will be alot higher on supply.