An electrical shock hazard can occur from contact with exposed utility power utilization, device control, and power supply conductors operating at potentials of 50 volts and above. Individuals involved in such uses must be trained in electrical safety and in proper lockout-tagout procedures.

Class 3b and 4 lasers should have a separate circuit and local cut-off switch (breaker) for the circuit.
Label and post electrical high voltage hazards and switches. Clearly identify the main switches to cut-off power. Before working on a laser, de-energize the machine. Positively disconnect it, if there is more than one source of power, disconnect them all. Lock out and tag the disconnect switches so that power is not reconnected while you are working on the laser.
Have at least two persons in an area while working on high-energy power systems.

Keep cooling water connections away from main power and high voltage outlets and contacts. Use double hose clamps on cooling water hoses. Inspect cooling water hoses and connections and power cables and connectors periodically as part of a regular equipment inspection. Check with Environmental Health & Safety on the proper installation of cooling water lines.

Laser Layout Guide (LLNL)

Reference: Section 3A, Environmental Factors: Electrical Power

Compressed Gases