Code requirement vs actual loading - diversity

[Dan Kissel]

I have a 1200 circuit breaker set at LSIG set at 1200A, 12 sec delay, 6000A. 3sec IsqT .3 with 1200 amps worth of cable feeding a 1200 distribution panel. A Fluke 435 Power quality analyzer measured the current for 7 days, which really captured the panels current load. All said and done the report for the highest amp draw which was over ~ 6. The distribution panels about 10 different control panels with eccentric loads. The meter can trap loads lasting 200 msec. The report indicates that the maximum peak current was ~700 amps but the average peak is only 358 amp with 95% of my load being under 321 amps.

Is the code concerned with the 700 amps which may happen for 200 msec or the avg peak of 358 amps. BTW the average current of the is 193 amps.

Th question other are asking how much available ampacity do I have left. The manufacture says, I am nowhere tripping the breaker ( only about 25 % used).

Does the code say I am using 700 amps of my 1200 capacity?

 

[d0nut]

Refer to 220.87 for the minimum requirements to use meter data to determine existing loading. It requires a minimum of continuous metering over a 30 day period to capture the maximum demand. The maximum demand is the highest average kW over a 15 minute interval. You can certainly use a shorter time period if you desire based on any unique loading scenarios for your facility.

 

[jim dungar]

Protective devices are applied based on nominal steady state currents. So your supplier is right.

You need to follow the NEC in order to determine how much available capacity you have. See post #2 by d0nut for one method.