On circuits above _____, all exposed metal parts of portable control devices should be grounded by a grounding conductor in the control cable.

On circuits above _____, all exposed metal parts of portable control devices should be grounded by a grounding conductor in the control cable.

• A. 50 amps
• B. 12 volts
• C. 50 volts
• D. 120 volts

Answer: (C)

Exposed metal parts on portable control devices become a shock risk when a fault can energize them. When circuits can reach 50 volts or more to ground, these metal parts must be bonded to a grounding conductor that runs with the control cable. This creates a low-impedance path for fault current back to the source, causing the protective device to trip quickly and reducing the danger to a person who might touch the part. If the voltage is only 12 volts, the rule doesn’t require this grounding because the shock hazard is much lower. While a 120-volt circuit would also require grounding, the standard uses 50 volts as the threshold.

Exposed metal parts on portable control devices become a shock risk when a fault can energize them. When circuits can reach 50 volts or more to ground, these metal parts must be bonded to a grounding conductor that runs with the control cable. This creates a low-impedance path for fault current back to the source, causing the protective device to trip quickly and reducing the danger to a person who might touch the part. If the voltage is only 12 volts, the rule doesn’t require this grounding because the shock hazard is much lower. While a 120-volt circuit would also require grounding, the standard uses 50 volts as the threshold.