System Capacity Evaluation

[Alecto]

I got this small job for a navy building where they are putting in new equipment (100 computers, monitors, network switches etc.) in one of the training rooms.

The job entails surveying the existing electrical system and making sure there is enough capacity to add this new equipment.

I can go see what size panel, breakers, cables are currently installed but can this really be done without taking load measurements? Maybe use one of those clamp on current meters to see how much it is using? I also thought about asking them for utility bills but I'm not sure that would do me much good since this is a huge building and only one room is being affected.

Thank You

 

[kingpb]

If you are only dealing with 1 panel, or maybe 2, then it should be easy enough to do a fied lsurvey of the existing equipment/loads, and build a connected vs running load table. The only other option would be to measure the load over a 30 day period.

 

[Julius Right]

In my opinion, you may use the voltage measured at utility source -preferable at transformer terminals, the your load current , power factor and the voltage at panel bus bar.
You may calculate the income cable impedance and to try to identify the cable cross section and the conductor material [copper or aluminum] then the ampacity.
Another problem it is the voltage drop which could limit the maximum load current and the short-circuit current. The last you could calculate if you would know the utility transformer power and the short-circuit impedance, only.

 

[petersonra]

I got this small job for a navy building where they are putting in new equipment (100 computers, monitors, network switches etc.) in one of the training rooms.

The job entails surveying the existing electrical system and making sure there is enough capacity to add this new equipment.

I can go see what size panel, breakers, cables are currently installed but can this really be done without taking load measurements? Maybe use one of those clamp on current meters to see how much it is using? I also thought about asking them for utility bills but I'm not sure that would do me much good since this is a huge building and only one room is being affected.

Thank You

They may have load calculations from when it was built. start from there and add in the new loads and see what you come up with.

otherwise you need to do a 30 day load study.

I don't see any other code legal ways to do this.