3 Phase Power

[bar123]

I need your opinion. A manufacturing plant is under renovation. It has a power source of 230v 3-phase. The management is planning to construct additional 2 storey building for canteen and 2 storey building for guard house. The canteen will use 3 air con (single phase) and for guard house will use one air con. The feeder for these two buildings will be connceted to the spare breaker of the distribution panel of the plant. Our engineer suggested that the feeder must be 3 phase. But in the electrical plan, it is designed as single phase only. which is more appropriate for this?

Thank you for your help.

 

[FreddyNurk]

It depends. Bigger air con or other things can make 3 phase more handy to have.

On the other hand, if a single phase can handle all the loads for a building, its probably easier to keep it single phase.

A 3 phase feed off the main board may give you more options later, but from here its really just a guess.

 

[waross]

It depends. There are a lot of things that you haven't told us.
230 Volt three phase was "phased" out in North America back in the '50s or '60s.
SO
Is this a legacy 230 Volt system or a 240 Volt or a 120:208 Volt or a four wire 120:240 Volt system?
How is the system grounded.
If this is a four wire system (120:240 three phase or 115:230 three phase) then it may be better to feed the new buildings single phase.
If the service is 120:208 it will be better to use three phase.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[PHovnanian]

What Bill said about some 230V 3 phase being eliminated.

Talk to your local utility about what voltages they will offer or prefer to offer. If they drag their feet about upgrading one of these legacy voltage systems for the increased load, you might be better off leaving the existing plant service alone and having a new service run for the canteen and guard house.

If the existing plant service is sufficient, then its permissable to run a single phase feeder off the three phase panel as long as the neutral voltage has the correct relationship to the line voltages. However, your engineer might have issues with panel/service capacity and/or load balance due to the addition of these new structures. If so, that could rule out a single phase tap.