Does my Induction Control Relay system require 2 or 3 electrodes?

The answer can be two or three depending on the installation. It depends on the grounding circuit. We recommend using a third common electrode for the ground circuit in all installations, the third electrode must extend below the longest operating electrode.

The following is the notation from page 2 of BW Controls 1500 Series Induction Control Relays the installation and Service manual.

Ground: A system ground return circuit is required from the indicated relay terminal to the liquid in order to complete the secondary circuit of relay. Conduit should not be used. Instead, connection should be made directly to uninsulated metal tank, or to metal pipe connected to tank below normal low liquid level.

In wells, connect ground to pump or metallic water pipe. For concrete, wood, or insulated tanks, use an extra common electrode extending slightly below the longest operating electrode

Page 2 of BW Controls 1500 Series Induction Control Relays the installation and Service manual.