Table 220.88

[de2]

(I search the previous entry and this topic was closed. I have a question and opening a new one).

I took 4 different kVA value and implemented the Optional method for Table 220.88.
Attached is the results.

Why Not All Electric Restaurant always have more kVA rating (therefore bigger service conductor size and OCPD) than All Electric Restaurant?
What I am missing here?

 

[de2]

no one has any idea?
Was I the only one who is thinking south?

 

[de2]

helloooo.

 

[Dennis Alwon]

It's Saturday not a lot of members on here and probably many don't want to do a calculation. I am getting ready to go out but I will look at it latter

 

[Dennis Alwon]

I took a quick look and I have no idea why all electric gets the demand factor especially in a restaurant.

 

[de2]

I took a quick look and I have no idea why all electric gets the demand factor especially in a restaurant.

That is what I am saying!!! All electric restaurant will have a smaller service cable than not all electric restaurant. What I am missing???

 

[david luchini]

That is what I am saying!!! All electric restaurant will have a smaller service cable than not all electric restaurant. What I am missing???

An all electric restaurant would mean more electrical equipment that has intermittent use or thermostatic control. More electrical equipment with intermittent use or thermostatic control means a larger demand factor.

 

[de2]

An all electric restaurant would mean more electrical equipment that has intermittent use or thermostatic control. More electrical equipment with intermittent use or thermostatic control means a larger demand factor.

I see your point but I am not buying this section of the NEC. Cant digest it well.
I think this should be deleted from the book.

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[Dennis Alwon]

I see your point but I am not buying this section of the NEC. Cant digest it well.
I think this should be deleted from the book.

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Write a proposal... or just wire it without the demand factor. A lot of thought goes into these demand factors and they have been there for many years so my guess is that it works.

 

[de2]

Write a proposal... or just wire it without the demand factor. A lot of thought goes into these demand factors and they have been there for many years so my guess is that it works.

This is also true. I agree.

NEC also say code book is just to basis design,minimun requirements, you can alway go further than what is the NEC mininum requirements are.

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[Dennis Alwon]

This is also true. I agree.

NEC also say code book is just to basis design,minimun requirements, you can alway go further than what is the NEC mininum requirements are.

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Of course, no one said you have to use the calculated load. That is just a minimum. I believe many of us on this forum tend to overdo our installations but we discuss what is code. As years go by it will usually reveal what doesn't work out hence the rewording of the NEC every 3 years. Calculations, however, have been pretty stable for some time.

 

[electrofelon]

That is what I am saying!!! All electric restaurant will have a smaller service cable than not all electric restaurant. What I am missing???

No. An all electric restaurant will require a larger service. Yes it may get more of a demand factor. You aren't really thinking about it correctly by just picking a kva value and treating them like the same thing.

 

[de2]

No. An all electric restaurant will require a larger service. Yes it may get more of a demand factor. You aren't really thinking about it correctly by just picking a kva value and treating them like the same thing.

Wait a minute, on my posted calculation all electric restaurant kva is smaller than not all electric restaurant kva. Therefore smaller kva / voltage gives smaller Amp, this gives smaller feeder , service cable.

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[david luchini]

Wait a minute, on my posted calculation all electric restaurant kva is smaller than not all electric restaurant kva. Therefore smaller kva / voltage gives smaller Amp, this gives smaller feeder , service cable.

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Take your 320kVA not-all-electric restaurant, and convert it to an all-electric restaurant. You will have to add all of the kva for the ranges, ovens, fryers, steam kettles, etc before you apply the all-electric demand factor.

You are not comparing equal restaurants.

 

[de2]

Take your 320kVA not-all-electric restaurant, and convert it to an all-electric restaurant. You will have to add all of the kva for the ranges, ovens, fryers, steam kettles, etc before you apply the all-electric demand factor.

You are not comparing equal restaurants.

I dont think you are right.

320kVA is calculated load, this means it includes what ever in the restaurant of the subject.(all electric restaurant, or not all electric restaurant)

So my understanding is;

320kva calculated load for All Electric Restaurant Service or Feeder will be calculated based on 172kVA.
320kva calculated load for Not-All Electric Restaurant Service or Feeder will be calculated based on 260kVA.

320kVA is already calculated load, means it includes what ever electrical equipments in the facility.

 

[david luchini]

I dont think you are right.

320kVA is calculated load, this means it includes what ever in the restaurant of the subject.(all electric restaurant, or not all electric restaurant)

So my understanding is;

320kva calculated load for All Electric Restaurant Service or Feeder will be calculated based on 172kVA.
320kva calculated load for Not-All Electric Restaurant Service or Feeder will be calculated based on 260kVA.

320kVA is already calculated load, means it includes what ever electrical equipments in the facility.

320kVA is the Connected Load. If you have a restaurant with a connected load of 320kVA where the major equipment is gas supplied equipment, and you decide to change it to an all-electric restaurant, the connected load is going to be larger than 320kVA. You will have to add the kVA for all of the gas equipment that you just changed to electric equipment.

 

[de2]

320kVA is the Connected Load. If you have a restaurant with a connected load of 320kVA where the major equipment is gas supplied equipment, and you decide to change it to an all-electric restaurant, the connected load is going to be larger than 320kVA. You will have to add the kVA for all of the gas equipment that you just changed to electric equipment.

But this table is for Brand new restaurant calculation, not for renovation.

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[david luchini]

But this table is for Brand new restaurant calculation, not for renovation.

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OK, you as an engineer are designing a restaurant that is planning to use gas for all of the major equipment. You come up with a connected load of 320kVA for the electrical.

The owner comes to you before the design is complete and says that it is too expensive to bring gas to the building, so the equipment will all be electric, and asks you to redesign the building.
When you complete your redesign, the connected load is going to be much greater than 320kVA because you had to add the kVA for the ranges, ovens, water heaters, dishwasher booster heater, etc, that were all originally gas equipment.

 

[LarryFine]

320kva calculated load for All Electric Restaurant Service or Feeder will be calculated based on 172kVA.
320kva calculated load for Not-All Electric Restaurant Service or Feeder will be calculated based on 260kVA.

320kVA is already calculated load, means it includes what ever electrical equipments in the facility.

The all-electric restaurant will have a much smaller cooking capacity. Everyone is suggesting that you should be comparing two restaurants with similar cooking capacities, not similar electrical capacities.