Load of an existing generator

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Urko

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Florida
Good evening,

I am working on a 3 stories existing building with electrical service 480/277 V 3ph. The building was built 10-15 years ago. The part of the building is on emergency gas generator with only one ATS (the installation does not comply with current code). The generator load includes emergency lighting, receptacles, and equipment. There is no as built drawings. How can I verify accurately the electrical load of the existing generator? Any input will be helpful.

Thank you in advance!
 
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topgone

Senior Member
Urko said:
Good evening,

I am working on a 3 stories existing building with electrical service 480/277 V 3ph. The building was built 10-15 years ago. The part of the building is on emergency gas generator with only one ATS (the installation does not comply with current code). The generator load includes emergency lighting, receptacles, and equipment. There is no as built drawings. How can I verify accurately the electrical load of the existing generator? Any input will be helpful.

Thank you in advance!
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  • There must be some meters in the genny! Ammeters and voltmeters perhaps. You can calculate from those.
  • Better still, install a kW meter on the generator output.
  • Or locate the kW-Hr meter (assuming an induction-type meter) and
    • look for the the kH of the meter (on the name plate of the meter).
    • This kH represents the number of revolutions the disc makes per kW-Hr.
    • Using a stopwatch, take the time it takes for the meter disc to complete say, 10 complete revolutions.
    • Your generator actual load will be =10 rev./(kH x time, in Hrs for ten revs) = kW
    ​
Hope that helps.
 
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