The gate contact is used to pass high voltage to a set of live wires mounted on a gate for a security electric fence. When the gate is open the gate is bypassed (gate wires are not live or monitored). It can also be configured to short the fence live wires to ground when the gate is opened to create an alarm.

This switch can be used for sliding or swing gates, so long as the swing gates alignment can be maintained. 

Here the gate-top, fence circuit forms part of the fence series circuit when the gate is CLOSED. The energy from the fence will loop through the gate circuit and back to the fence circuit. Cutting the wires on the closed gate will trigger an alarm.

Here the gate-top, fence circuit does not form part of the fence series circuit when the gate is OPEN. The energy from the fence will loop through the gate contact only and back to the fence circuit. Cutting the wires on the open gate will not trigger an alarm.