How to convert electric bill kWH to kVA?

[kwired]

Of course, there is no direct connection of the energy conservation concept with the thread. It is only an 'in case the OP implies it' point.

Well, what it means when NEC does not make voltage drop limits along the conductors mandatory (which ensures limiting energy loss) but just an option, for example?

NEC is about electrical safety not energy conservation.

I will say it has gone too far beyond safety with some of the requirements, but has not really encroached on energy conservation (so far).

Conservation is a design issue that goes beyond the safety requirements that are covered by NEC.

If you want to run a large conductor to prevent losses, NEC does not stop you from doing so.

It does prohibit running too small of a conductor where heating of that conductor could introduce other hazards.

We can debate what level of design/protection may provide a particular level of safety or should have been used in the NEC but the concept of NEC on that topic is still intended to be prevention of overheating of conductors and potential hazards that may develop at certain load levels and not a focus on how much energy may be "wasted" in a particular install.

We do have energy codes that focus on those types of things - though they are not always something enforced in all areas of the country.

 

[ggunn]

NEC 220.87 clearly shows how to calculate maximum demand for existing installations.

That calculation gives an estimate of what a building can demand. What the OP wants to determine is how much his building does demand. It's a completely different ball of wax.

 

[BackInBlack]

Completely agree with kwired. In fact, the NEC while by title is the electrical code, it is a chapter of the National Fire Protection Association, Chapter 70. So it is a safety code.

ggunn is correct, that is what I was trying to get.


Should this be continued? Only if someone here knows a way to find high demand in kVA from the utility bill.

 

[don_resqcapt19]

Completely agree with kwired. In fact, the NEC while by title is the electrical code, it is a chapter of the National Fire Protection Association, Chapter 70. So it is a safety code.
....

The NEC, NFPA 70, is not a chapter or a part of any other NFPA code or standard. It is a totally independent document.

 

[ggunn]

Completely agree with kwired. In fact, the NEC while by title is the electrical code, it is a chapter of the National Fire Protection Association, Chapter 70. So it is a safety code.

ggunn is correct, that is what I was trying to get.


Should this be continued? Only if someone here knows a way to find high demand in kVA from the utility bill.

I said this a while back but it may have gotten lost in the noise: If your utility assesses you a demand charge, the peak kW demand upon which that charge is based will almost assuredly be shown somewhere on your bill.

 

[Iron_Ben]

I said this a while back but it may have gotten lost in the noise: If your utility assesses you a demand charge, the peak kW demand upon which that charge is based will almost assuredly be shown somewhere on your bill.

At the POCO I worked for, a customer (commercial or industrial) went on a demand rate after three consecutive months of 5,000+ kWh. Once on, it was extremely hard to get off. This did not apply to residential customers however; they were *never* put on a demand rate. This was all mandated by the Louisiana PSC. Other states may do it differently.

Incidentally, there is a misconception that demand rates are always worse; more expensive. Not so. At our company they were worse if your load favor was low, and better if your load favor was high. They break even point was somewhere around a 45% load factor. Used to know it but have forgotten in old age.

 

[Iron_Ben]

At the POCO I worked for, a customer (commercial or industrial) went on a demand rate after three consecutive months of 5,000+ kWh. Once on, it was extremely hard to get off. This did not apply to residential customers however; they were *never* put on a demand rate. This was all mandated by the Louisiana PSC. Other states may do it differently.

Incidentally, there is a misconception that demand rates are always worse; more expensive. Not so. At our company they were worse if your load factor was low, and better if your load factor was high. They break even point was somewhere around a 45% load factor. Used to know it but have forgotten in old age.

ETA: changed "favor" to "factor" 2x

 

[BackInBlack]

The NEC, NFPA 70, is not a chapter or a part of any other NFPA code or standard. It is a totally independent document.

Disagree, it is chapter 70 of the NFPA, published by NFPA. Every printed copy of this chapter has the NFPA logo and title NFPA 70 on the front cover and first few pages. The Copyright of the book is by NFPA. NEC is a registered trademark of NFPA.

 

[david luchini]

it is chapter 70 of the NFPA,

The NFPA is not a book, it is an association. The NEC is one of the many codes and standards published by the NFPA, it is not a "chapter" of a larger standard.

 

[kwired]

70 is just their publication number for that particular document (more of a book to some then a document though)

 

[don_resqcapt19]

Disagree, it is chapter 70 of the NFPA, published by NFPA. Every printed copy of this chapter has the NFPA logo and title NFPA 70 on the front cover and first few pages. The Copyright of the book is by NFPA. NEC is a registered trademark of NFPA.

Yes, the NFPA owns and publishes the NEC, but it is a stand alone document. It is not a part of any other NFPA document.

 

[Haji]

What the table shows is a mean value for each listed usage. Without a corresponding standard deviation figure you have no way of knowing the extent to which you can depend on that estimate. For example for residential there can be as much as a factor of two difference in the load factor just based on whether there is someone home during the day or not.

NEC recognizes demand factor and not load factor. That does not mean load factor value is not as definite as demand factor value becaue there is a relation between two: Load factor=Average demand/[Demand factor*Connected load]

 

[Besoeker]

Well, my good golly gosh!
The discussion is still going!
About 45 posts after the question was answered.

 

[Haji]

NEC is about electrical safety not energy conservation.I will say it has gone too far beyond safety with some of the requirements, but has not really encroached on energy conservation (so far).Conservation is a design issue that goes beyond the safety requirements that are covered by NEC.If you want to run a large conductor to prevent losses, NEC does not stop you from doing so.It does prohibit running too small of a conductor where heating of that conductor could introduce other hazards.We can debate what level of design/protection may provide a particular level of safety or should have been used in the NEC but the concept of NEC on that topic is still intended to be prevention of overheating of conductors and potential hazards that may develop at certain load levels and not a focus on how much energy may be "wasted" in a particular install. We do have energy codes that focus on those types of things - though they are not always something enforced in all areas of the country.

Energy codes are not enforceable whereas NEC is. So people who do not want to comply with energy code are encouraged to do so by simply complying with NEC which requires only minimum sizes(of wires).

 

[kwired]

Energy codes are not enforceable

Tell that to most of those that do wiring in California and maybe a few other locations and see how that goes.

It may not be enforced by the same AHJ as the NEC is though.

 

[ggunn]

NEC recognizes demand factor and not load factor. That does not mean load factor value is not as definite as demand factor value becaue there is a relation between two: Load factor=Average demand/[Demand factor*Connected load]

This still does NOT mean that when you only know the kWh consumed in a month that you can calculate how many of those kWh were consumed in the 15 minute period of maximum demand during that month. You can establish an upper bound on it by knowing the service OCPD and conductor sizes and load breakers, etc., but that's not the information you need if you are trying to figure what your demand charges will be. Which was the original question from the OP, if anyone remembers.

 

[kwired]

This still does NOT mean that when you only know the kWh consumed in a month that you can calculate how many of those kWh were consumed in the 15 minute period of maximum demand during that month. You can establish an upper bound on it by knowing the service OCPD and conductor sizes and load breakers, etc., but that's not the information you need if you are trying to figure what your demand charges will be. Which was the original question from the OP, if anyone remembers.

I thought OP was trying to figure conductor size and/or overcurrent protection setting on the servcie. If there is demand charges being billed, POCO would have to have demand metering equipment as well as recorded usage data or else they have nothing to accurately determine the charges.

 

[ggunn]

I thought OP was trying to figure conductor size and/or overcurrent protection setting on the servcie. If there is demand charges being billed, POCO would have to have demand metering equipment as well as recorded usage data or else they have nothing to accurately determine the charges.

His question (from post #1): The question is how to convert kWH from a utility bill to kVA to find demand on a building for that billing period.

 

[Haji]

This still does NOT mean that when you only know the kWh consumed in a month that you can calculate how many of those kWh were consumed in the 15 minute period of maximum demand during that month. You can establish an upper bound on it by knowing the service OCPD and conductor sizes and load breakers, etc., but that's not the information you need if you are trying to figure what your demand charges will be. Which was the original question from the OP, if anyone remembers.

See the following post for calculation of maximum demand in KW

Suppose the OP's building is residential. The typical load factor for such a building is 0.42 per EPRI report. Suppose the average demand as worked out from the utility bill is 20 KW. Then from the equation for load factor, Maximum demand=20/0.42= 47.62 KW. This is an estimate for the maximum demand for the OP.

As NEC recognizes demand factor and there is a relation between load factor and demand factor

There is a relation between Load factor and demand factor:

Load factor=Average demand/[Demand factor*Connected load]

so the load factor may be used in calculations with same certainty as for the demand factor.

 

[Besoeker]

See the following post for calculation of maximum demand in KW

As NEC recognizes demand factor and there is a relation between load factor and demand factor

so the load factor may be used in calculations with same certainty as for the demand factor.

So how exactly does that answer the question posed?

The question is how to convert kWH from a utility bill to kVA to find demand on a building for that billing period.