What does the P3 (Earth Ground Fault) trouble code mean on the SK-5207, and how do I isolate the fault?

A P3 trouble indicates the panel has detected a short between earth ground (terminal 52) and circuit ground, which includes terminals 1, 10, 20, and 25 (Page 84) [1].

Isolation Steps:

1. Place a DC voltmeter with the negative lead on terminal 1 and the positive lead on terminal 52 (Page 84) [1].

2. Verify if the voltage is fluctuating between 0 and 2.5 volts; this is the normal range (Page 84) [1].

3. Disconnect field wiring from the panel one by one until the meter returns to the normal range to identify the shorted wire (Page 84) [1].

4. Alternatively, enter Accu-Zone Troubleshooting (Mode 25) by pressing 25 ENTER + Code (Page 88) [1].

5. In Mode 25, check Channel 31; a normal reading fluctuates between 1 and 9 (Page 86) [1].