Lockout / Tagout
Forms of Hazardous
Energy on Construction Sites
Energy on Construction Sites
OSHA 29 CFR 1910.147 · 1926.417 · All Energy Sources Must Be Identified Before LOTO
Lockout/Tagout is specifically designed to protect workers from the unexpected release of energy — but if you only think of electrical energy, you're missing the other five types that can kill or seriously injure workers on a construction site. Before any LOTO procedure begins, every energy source must be identified, isolated, and verified.
The Six Types of Hazardous Energy
- 1. Electrical: The most common. Includes stored charge in capacitors and UPS systems even after the main disconnect is opened — verify with a meter, not just by opening the switch
- 2. Hydraulic: Pressurized fluid in cylinders and lines — can release forcefully when fittings are opened. Bleed hydraulic pressure before working on any hydraulic system
- 3. Pneumatic: Compressed air in lines and receivers — bleed to atmosphere before disconnecting. Air at 100 PSI has enormous stored energy
- 4. Gravitational/mechanical: Suspended loads, raised equipment, elevated work platforms, compressed springs — support loads with mechanical blocking before working beneath them
- 5. Thermal: Steam pipes, hot process fluids, heated surfaces — allow to cool to below 115°F before contact. Verify temperature with a contact thermometer
- 6. Chemical: Pressurized chemical systems, reactive materials stored in sealed containers
Verification Is Not Optional
- Assuming a system is de-energized because you turned it off is how workers get killed
- After isolation: attempt to actuate the equipment (press the start button) — if it doesn't start, energy is isolated. If it starts, go back to step one
- Stored electrical energy in capacitor banks: discharge time can exceed 60 seconds — follow the manufacturer's specific procedure
Discussion Questions
- Name the six types of hazardous energy and give an example of each found on a typical NYC construction site.
- You open the electrical disconnect on a piece of equipment. Is the equipment safe to work on now? What additional step is required?
- A compressed air line is going to be disconnected. What must happen before you loosen the fitting?
- Name two examples of gravitational energy on this site that would require mechanical blocking before any maintenance work.
Sign-Off
Project Address
Date
Time
Foreman / Supervisor
SSM / SSC Name & License No.
Worker Attendance
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