# maximum amps consumption from electricity bill



## dhruvin (Dec 20, 2019)

I have an electricity bill of the whole year, from that how can I know how many maximum amps are consumed in a single day, I am looking for an answer the client wants to make sure that the new changes and addition of equipment will not affect the current panel board to be changed, the store is fed from 3P 208/120 PB


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## Cow (Jan 16, 2008)

You're going about this the wrong way. You have three options.

Do a load calc.

Call the power co. If they are using smart meters, you can get the peak demand for the last 12 mos.

Put a logger on the panel for 30 days minimum during a time period known to have the highest peak load using a 15 minute averaging sample rate.

There is no way to read kilowatt hours from a bill and determine the loading at any given time. The only way would be if the load was 100% steady, which a store is not and pretty much everything else, is not.


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## dhruvin (Dec 20, 2019)

I see, but I just have to give them an answer based on the electricity bill lol.

how about adding the following:

Electric Demand Charge (First 50 KW Used) :50 kW 
Electric Demand Charge (Above 50 KW Used) :67.2 kW


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## dhruvin (Dec 20, 2019)

also how to do a load calculation from an electricity bill? sorry if it's a dumb question


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## Cow (Jan 16, 2008)

Did you read my post at all? Or just skip over it?


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## gpop (May 14, 2018)

dhruvin said:


> also how to do a load calculation from an electricity bill? sorry if it's a dumb question


You can not.

you can calculate average use per day/hour but its not a load calculation.

Lets say i used 943kwh last month so that's divided by 30 days 

thats 31.4kwh per day divided by 24 hrs equals 1.3kwh per hour 1300w avg usage

If i was to do a load calculation this way i could run my home on a 12 ga drop cord

In real life my ac unit uses 3500w, my hot water heater uses 4500w and the oven uses 1000 to 5000w add a extra 1w per sq foot and im getting closer to peek demand which is used to calculate the size of the panel i require.


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## Southeast Power (Jan 18, 2009)

dhruvin said:


> I see, but I just have to give them an answer based on the electricity bill lol.
> 
> how about adding the following:
> 
> ...


Use the demand KW.
That’s your max.


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## NoBot (Oct 12, 2019)

Have the owner give you the power bills for the past 12 months. Look at the demand peak in KW. Choose the month that’s the highest and do the math


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## emtnut (Mar 1, 2015)

Sounds all pretty complicated if you ask me.

Do you have a friend that's an electrician that you could ask ?


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## VELOCI3 (Aug 15, 2019)

From the bill you know how many watts were used and the measurement period. If you know the service voltage and Ohm’s Law you can calculate the daily average.


Sent from my iPad using Tapatalk


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## splatz (May 23, 2015)

dhruvin said:


> I see, but I just have to give them an answer based on the electricity bill lol.


Super. Just pull some number out of your ass and go on with your life.


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## HackWork (Oct 2, 2009)

dhruvin said:


> I am looking for an answer *the client wants to make sure* that the new changes and addition of equipment will not affect the current panel board


So you are essentially certifying this. The client wants to be sure of something, so they brought in a "professional" to do so.

But you are doing it in a way that can't be done, and planning on just throwing out garbage numbers:


dhruvin said:


> I see, but I just have to give them an answer based on the electricity bill lol.


 You don't "have to" do anything. And you certainly should not be doing the wrong thing.

I hope you have Error and Omission insurance. Are you actually an electrical contractor?


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## VELOCI3 (Aug 15, 2019)

dhruvin said:


> I have an electricity bill of the whole year, from that how can I know how many maximum amps are consumed in a single day, I am looking for an answer the client wants to make sure that the new changes and addition of equipment will not affect the current panel board to be changed, the store is fed from 3P 208/120 PB




This question is usually asked as “can my existing equipment support an additional load”?

The way it’s answered is:

What is the new load type and size (motor, lighting etc.)

What current loads if any will be discontinued with this change.

What are the existing loads and are they continuous, seasonal, constant etc. (heating and AC equipment might not be in use at the same time)

When the new load is applied what are the possible load conditions occurring at the same time and have I figured for the overcurrent condition.

Or

There is the Calvin and Hobbes dad method:














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## nrp3 (Jan 24, 2009)

I would imagine that if you are somewhere cold and there's A/C in the heating system, that you wouldn't likely capture the peak anyway with a monitor this time of year.


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## splatz (May 23, 2015)

HackWork said:


> I hope you have Error and Omission insurance. Are you actually an electrical contractor?


I was sure it was a homeowner bull****ting their way past the signup requirements but the part about the 208 wouldn't fit there. I can certainly imagine a contractor asking for help, not knowing how to ANSWER this, but (all due respect to the OP) I think a contractor would be able to ASK this better.


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## HackWork (Oct 2, 2009)

I’m not a homeowner, I swear!


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## Funksparky (Nov 8, 2017)

HackWork said:


> I’m not a homeowner, I swear!




Time for you to buy a house and stop living in your van!


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## HackWork (Oct 2, 2009)

Funksparky said:


> Time for you to buy a house and stop living in your van!
> 
> 
> Sent from my iPhone using Tapatalk


But it's a sweet van.


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## 99cents (Aug 20, 2012)

HackWork said:


> You don't "have to" do anything.


Exactly!

We are not obligated to do whatever the customer wants. What we should feel obligated to do is look at things through our own eyes as experienced tradesmen.

I usually default to code and, in this case, code says do a load calc.


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## emtnut (Mar 1, 2015)

splatz said:


> I was sure it was a homeowner bull****ting their way past the signup requirements but the part about the 208 wouldn't fit there. I can certainly imagine a contractor asking for help, not knowing how to ANSWER this, but (all due respect to the OP) *I think a contractor would be able to ASK this better*.


Exactly ! It's one thing to need help, but if they don't even know how to ask the question, they probably shouldn't be doing it.
@Cow answered him, and still he didn't get it ...


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## HackWork (Oct 2, 2009)

emtnut said:


> Exactly ! It's one thing to need help, but if they don't even know how to ask the question, they probably shouldn't be doing it.


What if the utility meter has more volts flowing over the negative than the positive, would it still register the juice?


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## emtnut (Mar 1, 2015)

HackWork said:


> What if the utility meter has more volts flowing over the negative than the positive, would it still register the juice?



The good ol' days with the meter spinnin' backwards :biggrin:


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## JRaef (Mar 23, 2009)

Actually, even using the Peak Demand charges is not actually much better than an educated guess. let's say your Peak Demand is 100kW. That means that for a window of time, usually 15 or 20 minutes, the power peaked at 100kW. That *could *have been 200kW for half that time frame, zero for the rest. you just cannot effectively use an ENERGY meter as a POWER meter.


It needs to be actually calculated, as Cow said in his first response. You can't cheat the system...


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## pawanranta (Feb 18, 2020)

VELOCI3 said:


> From the bill you know how many watts were used and the measurement period. If you know the service voltage and Ohm’s Law you can calculate the daily average.
> 
> 
> Sent from my iPad using Tapatalk


My service voltage is 230V and I know the Ohm's lawa  
How do I calculate the peal amp demand for a certain period?


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## VELOCI3 (Aug 15, 2019)

pawanranta said:


> My service voltage is 230V and I know the Ohm's lawa
> How do I calculate the peal amp demand for a certain period?



That would have to be measured rather than calculated. If you have a smart meter from the power company they could tell you the average demand. I’m not sure if they archive daily data. If not rent a power analyzer with data logging. 


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## Southeast Power (Jan 18, 2009)

dhruvin said:


> I see, but I just have to give them an answer based on the electricity bill lol.
> 
> how about adding the following:
> 
> ...


Us the demand KW.
We do this all of the time, that means just about every week.
I would not install anything less than an 80kw at that site.
I have a data logger I use and it will always confirm what we see in the demand charges.


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## NoBot (Oct 12, 2019)

Southeast Power said:


> Use the demand KW.
> That’s your max.


I've done this several times and it's accurate. I called the PoCo to get the highest demand for the year.

I did it for a restaurant. I got the highest demand and added the new equipment and loads for an addition. I came up with an 800 amp service required. The other bid was lower by almost $5,000 so they went with him. The following summer, the owner called because he lost power. I went there on a busy Friday night and found a 400 amp main fuse blown and burnt. I explained my bid and 800 amp service requirement, then told him to call the other guy and walked out.


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## Wardenclyffe (Jan 11, 2019)




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