Multiple Controller Relay Design

Purpose

The drawing below is used when accessory devices are attached to the controllers. It should be used when master valves, pump starts and rain sensors are installed with multiple controllers. This allows these devices to be used without looping the common wire between the controllers. Interconnecting controller transformers is a violation of National Electric Code.

How It Works

Each controller is connected to its own dedicated relay. The controller's master valve circuit is used to energize the relay. When the relay’s contacts are closed, it allows the voltage from the additional transformer to activate the pump start and/or master valve. Since this voltage comes from a separate transformer located in the relay enclosure, it eliminates any possibility of interconnecting the controller commons. Any number of controllers can be operated simultaneously with this design.

What Can It Do

One side of the transformer voltage is supplied directly to the pump start and/or master valve through a fuse and is used as the common. The fuse prevents the transformer from opening in the event of a short in the pump start relay or master valve solenoid.

The other side of the transformer voltage is connected to terminals 7 & 9 on the relay. When the relay is activated by the controller, the transformer voltage is fed to contacts 4 & 6 respectively.

Using both sets of contacts allows the controllers to turn on the pump start, master valve or both. For example, if Controller A is connected to bubblers or spray heads that do not need the additional pressure from the booster pump, the wire leading from terminal 6 would not be used.

Do not use terminals 2, 5 and 8 in the specified relays, they are not installed in a double pole relay.

Rain Sensor

If a rain sensor such as a Rain-CheckTM is installed as shown, it is advised that an override switch be installed. This allows the sensor operation to be overridden if watering is desired, even though the sensor is active. Be aware that the controllers will still be sending 24 volts to the solenoids. This may shorten the solenoid life. Installing individual rain sensors at each controller would prevent this. If a rain sensor will not be used, do not install this feature.

What Components To Use

The drawing is designed around components that should be readily available at your local electronics store or from Newark Electronics. The installation will be easier if a relay socket is used, this allows for easier mounting and replacement.

Installation

There are two possible locations for the relays: at the controllers, or at the pump start. In either case, remember there must be a 117 VAC power source available.

The controller installation will be the most logical if there are multiple controllers clustered together at a single location. This installation requires a pair of wires from each controller to the relay. This is also the best installation method if the only device being operated is a master valve because of the need for a 117 VAC voltage source.

Locating the relays at the pump makes more sense when there are several controllers scattered throughout the job site. This method requires a pair of wires from each controller to the relay location.

The relays and transformer should be installed in a NEMA approved enclosure. This will protect the components from weather damage and vandalism.

Wiring

For ease of installation, it is recommended that relay sockets are used. The sockets have tabs for mounting purposes, and allow easy replacement of a defective relay. The drawing below details the terminal screw positions for the specified sockets. This is the top view of the socket.

What Other Designs Are Available

Many additional designs are available by calling the Rain Bird Specification Hotline 1-800-458-3005