What resistor value is specified for the personnel ground device?

What resistor value is specified for the personnel ground device?

• A. 200K ohm
• B. 1K ohm
• C. 50K ohm
• D. 2K ohm

Answer: (A)

A personnel grounding device uses a resistor in series to keep any fault current through a technician at a very safe level while still providing an effective ground path. The resistor value is chosen so that, even if a fault voltage appears on the path, the current stays well below levels that could cause a shock. Using a worst‑case fault voltage near common aircraft system levels (on the order of 100–120 volts), the current through a safety limit of about 1 mA would require a resistance of around 100–120 kΩ or more. A 200 kΩ resistor keeps the current to roughly 0.6 mA at 120 V (and much less at lower voltages like 28 V), which is safely below the annoyance/shock threshold but still provides a low-impedance path to ground. If the resistor were much smaller, say a few kilo-ohms, the potential fault current could climb into tens of milliamps, which could be hazardous. If it were much larger, grounding effectiveness would diminish and static control could be insufficient. Therefore, 200 kilo-ohms is chosen to balance safety with effective grounding.

A personnel grounding device uses a resistor in series to keep any fault current through a technician at a very safe level while still providing an effective ground path. The resistor value is chosen so that, even if a fault voltage appears on the path, the current stays well below levels that could cause a shock.

Using a worst‑case fault voltage near common aircraft system levels (on the order of 100–120 volts), the current through a safety limit of about 1 mA would require a resistance of around 100–120 kΩ or more. A 200 kΩ resistor keeps the current to roughly 0.6 mA at 120 V (and much less at lower voltages like 28 V), which is safely below the annoyance/shock threshold but still provides a low-impedance path to ground.

If the resistor were much smaller, say a few kilo-ohms, the potential fault current could climb into tens of milliamps, which could be hazardous. If it were much larger, grounding effectiveness would diminish and static control could be insufficient. Therefore, 200 kilo-ohms is chosen to balance safety with effective grounding.