Balancing power panel loads

When three-phase power is used, and depending on the system configuration, the phase currents can be fully balanced or unbalanced. System configurations with three BPRs per BPA have balanced power panel loads, while configurations with only one or two have unbalanced loads. With two BPRs per BPA, two of the three-phases draw an equal amount of current, and are, nominally, 57.8% of the current on the third phase. With one BPR per BPA, two of three-phases carry an equal amount of current, with no current drawn on the third phase. The following figure is an example of feeding several loads of this type from two power panels in a way that balances the load among the three-phases.

Figure 1. Power panel load balancing

The method illustrated in the preceding figure requires that the connection from the three poles of each breaker to the three-phase pins of a connector be varied. Some electricians might prefer to maintain a consistent wiring sequence from the breakers to the connectors. The following figure shows a way to balance the load without changing the wiring on the output of any breakers. The three-pole breakers are alternated with single-pole breakers, so that the three-pole breakers do not all begin on Phase A.

Figure 2. Power panel load balancing

The following figure shows another way of distributing the unbalanced load evenly. In this case, the three-pole breakers are alternated with two-pole breakers.

Figure 3. Power panel load balancing