Calculate available circuit capacity

[manolete30]

I am measuring current on the main feeders of a distribtion panelboard. Most of the load is continous load. If I use an ammeter to measure existing load on main feefer. This reading take into consideration the 125% of continuos load? If I want to measure available capacity on feeder, can I assume I can go 100% of capacity or 80% of capacity on the feeder?

 

[charlie b]

This reading take into consideration the 125% of continuos load?

It does not. It measures what is flowing at the moment.

If I want to measure available capacity on feeder, can I assume I can go 100% of capacity or 80% of capacity on the feeder?

If you are planning to add load to an existing feeder, and if you intend to use load measurements as the means of verifying that there is spare capacity, then you will need 30 days worth of measurements. You take the highest demand observed during that period, and multiply that value by 125%, in order to determine the existing load.

See 220.87.

 

[manolete30]

Feeder load cosidering 125%

Feeder load cosidering 125%

Thank you very much for your response.

Question:

When you have more than three current carrying feeders in a conduit you also has to apply an adjustment factor according to code. This is applied in addition to the 125% of the top measured load in a 30 days period?

Can you recommend me a book to read about calculating available capacity in an exisitng facility and factors to consider. I am evalauting communication facilities with not more 100KVA substation.

 

[manolete30]

Thank You

Thank You

CAn you recommend me a book?