A circuit operating at 50 V or less shall be treated as a hazardous circuit if the power in it can create electrical shocks, burns, or an explosion due to electric arcs. Inductive circuits may create highvoltage hazards when interrupted. Observe all of the following rules for such circuits:

1. Provide protective covers and/or barriers over terminals and other live parts to protect personnel.

2. By suitable marking, identify the hazard at the power source and at appropriate places.

3. Consider magnetic forces in both normal-operation and short-circuit conditions. Use conductors that have appropriate physical strength and are adequately braced and supported to prevent hazardous movement.

10.8.2.3 OPERATION AND MAINTENANCE

Follow these guidelines for working on circuits operating at 50 V or less that are treated as hazardous:

1. Work on such circuits when they are de-energized.

2. If it is essential to work on or near energized low-voltage, high-current circuits, observe the safety rules as if the circuits were operating at more than 50 V. Refer to Section 2.1.2, "Considerations for Working on Energized Systems and Equipment" and 2.13.4, "Safe Energized Work (Hot Work)."

10.8.3 CONDITIONS OF HIGH VOLTAGE AND LOW CURRENT

10.8.3.1 HAZARDS

When the output current of high-voltage supplies is below 5 mA, the shock hazard to personnel is low. Where combustible atmospheres or mixtures exists, the hazard of ignition from a spark may exist. High-voltage supplies (ac or dc) can present the following hazards:

1. Faults, lightning, or switching transients can cause voltage surges in excess of the normal ratings.

2. Internal component failure can cause excessive voltages on external metering circuits and lowvoltage auxiliary control circuits.

3. Overcurrent protective devices such as fuses and circuit breakers for conventional applications may not adequately limit or interrupt the total inductive energy and fault currents in highly inductive do systems.

4. Stored energy in long cable runs can be an unexpected hazard. Safety instructions should be in place to ensure proper discharge of this energy.

5. Secondary hazards such as startle or involuntary reactions from contact with high-voltage low-current systems may result in a fall or entanglement with equipment.