Abstract: The number of poles on an electromagnetically operated contactor is increased by mounting one or two power pole modules to its sides. Each power pole module includes a housing which encloses a set of main line contacts that are coupled to the contactor for operation by its slidably mounted actuator. Flexible fastening elements on the power pole module mate with corresponding mounting elements formed on each side of the contactor to facilitate attachment of the module. Symmetrical loading on the contactor actuator is maintained by mounting power pole modules on each side of the contactor, or by using in place of one of them, a load balancer cartridge which simulates the loading of a module.