220V SP vs 208V 3P

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janb

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I have a customer that has a couple of commercial bakery convection ovens.
They are rated both SP and 3P. Since the space needs a new service, he has the option of either. What can I tell him about the advantage, energy efficiency of these choices? His friend (who is in the bakery business) tells him 3Phase is the only way to go.
 
Watts are watts regardless of the phase. You may be able to run smaller conductors to the ovens with three phase but of course you have to run one more of them.

In the long term 3 phase may make more sense as it gives him more flexibility in the future if he wants to buy a three phase mixer or dishwasher etc.
 
Bob may correct me but I have always been taught that 3 phase motors are more efficient (HP to HP) so if his equipment is available either way that may have a bearing. In addition, 3 phase motors have less working parts than single phase and are usually less maintenance/failure prone.
If 3P or SP is available at the same upfront cost, I would go 3 phase.
 
augie47 said:
Bob may correct me but I have always been taught that 3 phase motors are more efficient (HP to HP) so if his equipment is available either way that may have a bearing. In addition, 3 phase motors have less working parts than single phase and are usually less maintenance/failure prone.
If 3P or SP is available at the same upfront cost, I would go 3 phase.
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No on the efficiency issue. It may have been true some time ago, but watt-for-watt they are pretty much the same, and in fact on smaller motors 1P may even beat out 3P by an RCH. But yes on the moving parts / reliability issues for sure; go 3 phase if you can.

One other thing though. A lot of PoCos will let you get away without a kVAR meter (and the subsequent possibility of Power Factor penalties) on small 1 phase services for light commercial customers, but will tag you with it for any 3 phase service. So in the long run, 3 phase may end up costing more even if the energy use is the same. You would need to ask up front.
 
Jraef said:
One other thing though. A lot of PoCos will let you get away without a kVAR meter (and the subsequent possibility of Power Factor penalties) on small 1 phase services for light commercial customers, but will tag you with it for any 3 phase service. So in the long run, 3 phase may end up costing more even if the energy use is the same. You would need to ask up front.
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But a bakery will be mostly resistive load, I'd think. In any case, it's a close call, with the decider likely tariffs/co$ts.
 
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