What is the correct procedure for isolating and clearing a ground fault on the iO1000 SLC loop versus a NAC ground fault?

To isolate an iO1000 SLC loop ground fault, use the Fast Ground Check tool in the panel menu to increase the testing frequency (Page 216) [3].

If the LCD displays a specific device address, the fault is on the positive leg of that device's input; if no address is shown, the fault is on the loop controller or smoke power circuit (Page 212) [4].

SLC Isolation Procedure: 1. Open both conductors of the loop at a point that disconnects approximately 50% of the devices (Page 165) [2].

1. If the Ground Fault LED clears, the fault is in the disconnected portion. 3. If the LED remains on, the fault is in the first 50% of the loop. 4. Reconnect and repeat the process at a new point until the segment is isolated (Page 214) [4].

For NAC ground faults, the iO1000 detects impedance between 0 and 5 kΩ (Page 22) [3], though some EST manuals specify 10 kΩ (Page 212) [4].

To verify detection, short one leg of the circuit to chassis ground; the Ground Fault and Trouble LEDs must illuminate (Page 70) [8].

On BPS series supplies, a ground fault will open the Sense 1 and Sense 2 contacts (Page 36) [1].