Demand load

[JMWElectric]

Hello Everyone,

I have recently came across a project here in Northern California where the city is requesting we show a load calculation for the entirety of a 1200A switchgear/service for the building before signing off on our plans to insure we wont overload the ampacity. They asked specifically for a "Peak Demand Load" over a 10 day period.

I am curious what methods anyone has used to calculate this I am currently considering installing a usage meter by Eyedro and seeing what information it would produce. I have never done this and I am looking for an example on how to move forward.

Thank you!

 

[Dennis Alwon]

Hello Everyone,

I have recently came across a project here in Northern California where the city is requesting we show a load calculation for the entirety of a 1200A switchgear/service for the building before signing off on our plans to insure we wont overload the ampacity. They asked specifically for a "Peak Demand Load" over a 10 day period.

I am curious what methods anyone has used to calculate this I am currently considering installing a usage meter by Eyedro and seeing what information it would produce. I have never done this and I am looking for an example on how to move forward.

Thank you!

Imo, that is the job of an engineer not an electrician.

 

[Dennis Alwon]

Here are your options

220.87 Determining Existing Loads. The calculation of a
feeder or service load for existing installations shall be permitted
to use actual maximum demand to determine the existing
load under all of the following conditions:
(1) The maximum demand data is available for a 1-year
period.
Exception: If the maximum demand data for a 1-year period is not
available, the calculated load shall be permitted to be based on the
maximum demand (the highest average kilowatts reached and maintained
for a 15-minute interval) continuously recorded over a minimum
30-day period using a recording ammeter or power meter
connected to the highest loaded phase of the feeder or service, based on
the initial loading at the start of the recording. The recording shall
reflect the maximum demand of the feeder or service by being taken
when the building or space is occupied and shall include by measurement
or calculation the larger of the heating or cooling equipment load,
and other loads that may be periodic in nature due to seasonal or similar
conditions.
(2) The maximum demand at 125 percent plus the new load
does not exceed the ampacity of the feeder or rating of
the service.
(3) The feeder has overcurrent protection in accordance
with 240.4, and the service has overload protection in
accordance with 230.90.