ECN Forum Forums Code Related Discussion Canadian Electrical Code Topics Estimating available capacity based on peak demand

Hello,

I wanted to inquire if it is possible to estimate available electrical capacity in an electrical distribution system based on only peak demand information available. For e.g. if an 800A, 347/600V, 3-phase electrical service has a peak demand of 175kW, would it be safe to assume the following calculation to estimate available electrical capacity at unity power factor:

800A x 0.8 = 640A (max. loading)
175kW = 600V x A x 1.732 i.e. A = 168A
Available capacity would be 640A - 168A = 472A.

Would the estimation of available capacity change if there are 600V - 208V step-down transformers downstream of the electrical distribution system?

Thank you.

You will have to calc the existing loads on each of the transformers.

The code now allows this. You have to provide at least 12 months of peak demand data from the utility bills.