The Neutral-Earth voltage detector included in the HP12-TR Rack Mount, Wall Mount, and HP6C Rack Mount dimmers has been found to be too sensitive, causing the dimmer to indicate a fault condition when no fault is present. This can cause repeated nuisance tripping of the Neutral-Earth detector, and affects HP dimmers manufactured with serial numbers up to and including I98604.

The cure involves adding a 10K resistor in parallel with the existing R13 (220K) on the power circuit board. This resistor is located adjacent to the front panel flat cable connector at the front right-hand side of the Power PCB.

If nuisance tripping of the Neutral Earth detector occurs it is recommended the Neutral-Earth detector be disabled. Note that when the detector is disabled loose or broken Neutral connections will not be detected and damage may result to output loads.

To disable the Neutral-Earth detector:
1. Press the "Mode" button
2. Use the encoder to select "P.FLT"
3. Press the "Enter" button
4. Use the encoder to select "OFF"
5. Press the "Enter" button

Once disabled the Neutral-Earth detector will remain disabled until the detector is reenabled or the dimmer is Deep Cleared.

To re-enable the Neutral-Earth detector:
1. Press the "Mode" button
2. Use the encoder to select "P.FLT"
3. Press the "Enter" button
4. Use the encoder to select "ON"
5. Press the "Enter" button