One of the most common uses of the relay is as a pump start relay. The pumps used for irrigation systems operate on 117 VAC or higher. The contacts of the 621970 relay are rated at 10 amps (per pole) at 240 VAC. If your pump or other devices has a higher current or voltage requirement, then contact an electrical supply for the availability of a different relay. Relays are available in a very wide range of shapes, sizes and electrical characteristics.
The example below will explain the use of the relay to activate a 117 VAC booster pump. The booster pump should operate only when the controller is activating one of its stations. With most controllers, when one of the stations is activated, 24 volts is supplied between the common and pump start terminals. There are some controllers that supply 117 VAC to the master valve terminals. DO NOT use the 621970 relay in this situation.
The controller common should be connected to terminal A. The pump start wire from the controller will now be connected to terminal B. (When using the 621970 relay, be sure that only 24 VAC is being supplied between the common and pump start terminals.)
The black “hot” wire will run from the electrical service to terminal 7, the wiper for pole 1. Figure 4 uses pole 1, but any one of the three poles may be used.
The black wire going to the pump will be connected to terminal #4, the normally open contact of pole 1. The white “common” wire and the green ground wire will run directly from the electrical service to the booster pump. No other connections to the relay are necessary. Refer to figure 4.
Common From electrical service Ground from electrical service
____ 3 ____ 6
Black wire to Booster Pump
Black hot wire from electrical service
From controller common From controller 24 VAC Pump Start