Balancing 3 phase panel

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Cletis

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Getting ready to balance out a 3 phase panel. The original plan went to hell in a hand basket and we have all types of additions/deletions but my question is what's the "protocol" on maximum unbalanced current you would want in a 3 phase 120/208 4 wire system on a 225 amp panel which is 50% HVAC/Machines in a building.
 
Cletis said:
Getting ready to balance out a 3 phase panel. The original plan went to hell in a hand basket and we have all types of additions/deletions but my question is what's the "protocol" on maximum unbalanced current you would want in a 3 phase 120/208 4 wire system on a 225 amp panel which is 50% HVAC/Machines in a building.
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AFAIK there is no "protocol" for this. As long as no single line is overloaded, it comes down to minimizing voltage drop and keeping the utility happy. If they are not measuring and penalizing phase imbalance there will be no magic number to meet.
The "all types of additions/deletions" leads me to say to just do a proper panel schedule for the loads that ended up being there and keep the big ones from all piling up on one line or phase.
 
GoldDigger said:
AFAIK there is no "protocol" for this. As long as no single line is overloaded, it comes down to minimizing voltage drop and keeping the utility happy. If they are not measuring and penalizing phase imbalance there will be no magic number to meet.
The "all types of additions/deletions" leads me to say to just do a proper panel schedule for the loads that ended up being there and keep the big ones from all piling up on one line or phase.
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Ok, generally I always get them under 10 amps or so when I'm done shuffling the phases around but never really knew of any rules. I ran a 4/0 Al XHHW-2 for the neutral anyhow just in case
 
The panel won't care if you put all the load on one line as long as it's amp rating isn't exceeded.

The source may not respond as well to such a thing.
 
As designers and installers, we should do our best to show that the load is balanced. But in reality, the owner will not be considering what load is on which phase as they start turning things on and off. So at any given moment, the loads could be severely out of balance, and there is nothing you and I can do about that.
 
charlie b said:
As designers and installers, we should do our best to show that the load is balanced. But in reality, the owner will not be considering what load is on which phase as they start turning things on and off. So at any given moment, the loads could be severely out of balance, and there is nothing you and I can do about that.
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The most critical time for balance is when the loads are highest, so balance with a representative "everything on" scenario and let the lower load profiles fall where they may. (Assuming you have enough information to do that.)
 
GoldDigger said:
The most critical time for balance is when the loads are highest, so balance with a representative "everything on" scenario and let the lower load profiles fall where they may. (Assuming you have enough information to do that.)
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True

i like to mix my Kitchen Circuits around so Heavy use moves around the Service more Balanced

over the course of 200 Units . 3 PH Service …

I have never had a Problem Balancing A Service …

Mainly Common Sense .

Don
 
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