calculating ampere load on 3 phade service entrance conductors

[arcticsparky]

There are 3 parallel 500 mcm conductors feeding a 3 phase 4 wire service buss.
Reading the amperes on one conductor of each of the phases the Fluke 434 Power quality analyzer shows approximately 80 to 87 amperes per conductor. Question: To get the total amperes does one multiply the ampere reading times the number of parallel conductors per leg and then add the legs?

 

[kingpb]

The number of amps measured is just that; per conductor, per phase. If you are going to make an assumption that the each parallel conductor is carrying the same amount of current, then you can simply multiply the 1-conductor reading by 3 (e.g. 3 parallel conductors).

Adding the "legs" it is assumed you mean each of the 3 sets of conductors that make up the three phases. If that is the case, NO, you do not add these.

Perhaps you could expand on what you are planning to do with the info, so that someone may offer information on what to do next.

If you want to know the service size, then determine the total KVA by making the assumption that the pf is approx. "1.0" in each phase, and add the phases. Then you can divide to get average current.

Th other method would be to measure all three, and use the highest as the maximum (recommended).

 

[weressl]

There are 3 parallel 500 mcm conductors feeding a 3 phase 4 wire service buss.
Reading the amperes on one conductor of each of the phases the Fluke 434 Power quality analyzer shows approximately 80 to 87 amperes per conductor. Question: To get the total amperes does one multiply the ampere reading times the number of parallel conductors per leg and then add the legs?

Presume you meant to say 3 parallel conductors PER phase.
In that case you simply add up the current in each conductor per phase and that will be the current for that phase. To calculate the power consumption of the three-phase circuit for kVA you calculate the average current I=(Ia+Ib+Ic)/3, then use the following fomula:
P(kVA)=[1.73(Square root of 3)*U(line-to-line Volts)*I(average Amperes)]/1000.

To arrive at kiloWatts you would need to know the power factor, that is tricky to measure and usually require an instrument taht would give you the total kW reading anyway.