Substations & High-Voltage Equipment

A substation steps voltage up or down and routes power to homes and businesses. It holds equipment at voltages that can arc across air and kill without touching. Only qualified people may work inside the fence.

• Utility Workers
• Electricians
• Contractors

Who may enter

• Only qualified persons, or people escorted by one, may enter. See Qualified vs. Unqualified Persons.
• Contractors need a site orientation from the owner covering hazards, boundaries, work permits and emergency contacts.
• The public must never enter. Fences, locked gates and warning signs are there to stop them.

Main hazards

• Electric shock and arcing: at high voltage, arcs can jump through the air. Keep minimum approach distances that depend on voltage.
• Step and touch potential: during a fault, voltage in the ground can shock you across your feet. See Step & Touch Potential.
• Stored energy: capacitors, long cables and charged equipment can hold energy after de-energizing.
• Induced voltage: parallel lines can induce a dangerous voltage on a line that is turned off.
• Oil and gas: transformers hold insulating oil that can burn or explode; SF6 gas can displace air in low areas.
• Cranes and tall equipment: a boom, ladder or pole near energized parts can cause contact or flashover.

How work is made safe

1. The owner issues a work permit or clearance that defines exactly what is de-energized.
2. The equipment is isolated, locked out and tagged. See Lockout/Tagout.
3. The worker tests for absence of voltage with a proper tester and applies protective grounds where required. See Absence of Voltage Testing.
4. Everyone gets a job briefing about boundaries, hazards and emergency steps.
5. Equipment, tools and ladders are kept at or beyond minimum approach distances from energized parts.

Safety checklist

• Do I have permission and an escort or authorization?
• Have I been briefed on boundaries and approach distances?
• Is the work covered by a clearance, and is the equipment locked out and tested?
• Is a rescue and emergency plan in place?

Last updated: October 8, 2026