Telect's Load Sharing or Fail Safe panels use Schottky diodes cross-connected at the input to the power distribution circuits with isolated returns. When both power supplies are energized in a dual-circuit panel, power is balanced between the two supplies by the diodes. If one power supply loses its power or is shut down, the other supply shares its power with both outputs (A and B) through the Schottky diodes. The battery return circuits for A and B need to be made common external to the Telect panel since both circuits must operate from either the A or B power source.
Telect does offer a Load Sharing panel that includes an internally connected common return for both A and B sides, P/N 20HPGMT05FSR. This panel does not require the A and B side circuits to have an external common return.