Clamp Meter to Find Current Drawn

Thanks thats a great answer..

But if i then measured 200A on one phase how much more current could I pull ..

The other phases may have a 150A reading

Could I just say 50A is left in the supply at that instant ? I'm guessing it's not that simple

Well, if you are in the US, you can only load a circuit to 80% of it's rated capacity continuously, so assuming you have a 250A breaker ahead of this panel, 200A is it.

Unfortunately it is not that simple. You are working in three phase (I assume) - unbalanced load.

If the loads are individual then you can load the other phases/ redistribute the loads.

But if you are on three phase loads (or majority is three phase) then you have to pause and find the reason of the unbalance.

For single phase loads, you can approximately take average (assuming the supply is balanced and the power factors are almost same for all the three)

Average is not quite right. Square root of (average of squares) is more appropriate. Unless it is a balanced load, in which case, square root of (average of squares) will be equal to average...

It is assumed that the supply is a balanced 3 phase,if u clamp on any phase and you get thesame reading say L1-100A, L2-100A, L3-100A, then yr current drawn is 100Amps,but if one of the three is higher say 105A, take yr current drawn to be 105Amps.

If you dont have a balanced load, u may not get accurate result or information.

Patrick Whowha

Hi, if a balanced 3 phase load is connected, all 3 phases- R, Y and B, will show the same current drawn,so the current drawn(I) will be I=Ir=Iy=Ib. If an unbalanced load is connected, the 3 phases will show different currents. The answer to the question of how much current is being drawn should then be Ir in phase R, Iy in phase Y, and,Ib in phase B. This is so because one needs to know the current drawn mainly to find out how much more load can be connected. In a 3 phase supply, lets say a 200A supply, one can connect at max 200A load in each phase. To understand it more clearly, think of the fact that 1 three phase transformer can be formed from 3 single phase transformers. Suppose the rating of a single phase transformer is (supply side)100A:200A(load side). Just like you can connect a 200A load in this transformer, similarly, in a three phase transformer of same rating , you can connect a 200A load in each of the 3 phases.