The 16/3 CSA Approved wire is usable for the installation of your sprinkler system controller. This 6' cord and plug is used to allow an indoor/outdoor model controller with an internal transformer; to be plugged into an electrical outlet instead of hard wiring the controller to the power supply.
An electrical Conduit Body & Cover should also be used when using this pig tail cord to install a sprinkler controller. The Conduit Body & Cover screws right into the bottom of the controller.
All electrical codes should be followed when working with any electrical installations.