Wiring instructions for GFR-3 All load cables, including the neutral (if used), should pass through the window of the sensor. All wiring to the GFR-3 Ground Relay System should be rated 600V. Use a minimum of number 14 AWG. Ensure that safety requirements are met as per your local electrical code. The conductors from the Sensor to the GFR-3 Relay carry very low current. Extra care should be taken to keep this wiring at least 10 cm away from the power conductors. The wiring should be set up as a twisted pair and grounded at one point only. If the length of wiring exceeds 1.5 m, the twisted pair should be shielded and grounded as shown below.