220.87 Determining Existing Loads

[JohnHess]

Just be sure you're not off by a factor of four.
Kilowatts are a rate. A kWh is a kilowatt that ran for an hour.
One kW for 15 minutes is .25 of a kWh.

Saying "1 year worth of 15 minute increments. I sorted it with the highest first, which was 1.7 kWh" makes no sense.

What would make sense the highest 15 minute bucket averaged 1.7kW ( 7 amps ).

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That’s the only information they offer, the kWh usage in 15 minute increments.

 

[jim dungar]

That’s the only information they offer, the kWh usage in 15 minute increments.

Are you sure it is not kW. Average demand usage is usually kW.
Although I have never seen it, maybe you really are getting 15 minute usage and not the highest demand.

Look at any billing period and add up your recorded 15 minute values for that full month, they should be equal if the intervals are usages.

 

[JohnHess]

It shows thousands of lines of this. On the options page there’s no option for kW. I guess because they don’t offer demand readings for residential customers. It just says download usage data.

 

[brycenesbitt]

You can work it out with a bit of spreadsheet math. Do a pivot table turn the 15 minute data into hourly or daily data.
And compare with the same bill, as @jim dungar indicated above.

 

[wwhitney]

Yes, so I just downloaded the data from a house, 1 year worth of 15 minute increments. I sorted it with the highest first, which was 1.7 kWh. That is 6.8 kW which comes to 28 Amps.

That procedure is correct for data of the form "kWh used during a given 15 minute interval". Which is what I would expect a watt hour meter to record. Not sure why people seem to be giving you a hard time. 28A average current over the worst case 15 minute interval for the given year of data.

Cheers, Wayne

 

[jim dungar]

Not sure why people seem to be giving you a hard time.

Not giving a hard time, just getting on the same page.
My experience with 15 minute interval data has always been for KW Demand not KWH.

 

[JohnHess]

That procedure is correct for data of the form "kWh used during a given 15 minute interval". Which is what I would expect a watt hour meter to record. Not sure why people seem to be giving you a hard time. 28A average current over the worst case 15 minute interval for the given year of data.

Cheers, Wayne

Yeah, I understand what people mean when they say that kWh can’t be used to determine the demand. Usually the reading is over a longer period of time and you don’t know whether a small amount of current is being drawn the entire time or a very high amount of current is being drawn for a very short period of time.

But if we could look at an entire year and see that the highest kWh used during any 15 minute period was 1.7 kWh, then it seems like we could extrapolate that to 28 Amp being the actual maximum demand.