During lockout/tagout, what must be verified before maintenance begins?

• A. The system has zero energy confirmed and all energy sources isolated and locked out.
• B. The system is ready for restart after a quick test.
• C. Only tags are applied.
• D. Only one energy source is locked out.

Answer: (C)

The essential safety step is to confirm zero energy and ensure every energy source is isolated and locked out before maintenance begins. This means shutting down the equipment, isolating all energy sources (power, hydraulics, pneumatics, springs, valves, etc.), and applying lockout devices so the system cannot be energized again. Only after this physical protection is in place should you verify that there is no residual or stored energy, typically through proper testing. Relying on tags alone does not provide adequate protection because tags are warnings and do not physically prevent re-energizing. So, the correct approach is to verify zero energy and complete locking out of all energy sources before maintenance starts.