Electrical Lockout/Tagout and Other Energy Sources to Control

Most people picture a padlock on an electrical disconnect when they think about lockout/tagout. Electrical energy is the most common hazard, and it’s where most procedures start. But it’s rarely the only energy source on a machine, and the ones that get missed are the ones that hurt people.

Cal/OSHA Title 8, Section 3314 (the California standard for controlling hazardous energy) requires you to identify and control every energy source on a piece of equipment before someone services it. Not just the one that powers the motor. If a machine stores compressed air, holds hydraulic pressure, or has a die that can drop under gravity, all of that has to be isolated and verified before the work starts.

This piece breaks down the energy types your facility has to account for, the devices used to control each one, and where multi-energy equipment trips people up. For the full picture of how a compliant program comes together, see our lockout/tagout program development guide.

The Six Types of Hazardous Energy

Every machine in your facility runs on one or more of these six energy types. A complete procedure addresses each one present on the equipment.

Electrical. The most common and most recognized. CNC machines, conveyor motors, plating tank rectifiers, pumps, and control panels all carry electrical energy. Electrical lockout/tagout usually means opening a main disconnect or circuit breaker and applying a lock so it can’t be re-energized. Stored electrical energy in capacitors also has to be discharged before the equipment is considered safe.

Mechanical. Energy stored in moving or tensioned parts: flywheels that keep spinning after power is cut, belt drives, gears, and springs. Cutting power doesn’t stop a flywheel. It has to come to rest or be physically blocked.

Pneumatic. Compressed air systems, spray booths, clean-in-place (CIP) lines, and air-actuated clamps. Closing a disconnect doesn’t release the air already in the lines. Pneumatic energy has to be bled down through a vent or relief valve and verified at zero.

Hydraulic. Presses, lifts, and injection molding machines hold pressure in their hydraulic systems even after shutdown. That pressure can move a ram or platen. It has to be relieved and confirmed before anyone reaches in.

Thermal. Ovens, furnaces, heat-treatment equipment, boilers, and autoclaves hold heat and steam. A procedure that only locks out the electrical supply leaves a worker exposed to burns. Thermal energy requires isolating the heat or steam source and allowing a cooldown.

Gravitational. Suspended loads, elevated dies, raised forklift forks, and lift tables. A part held up only by hydraulic or pneumatic pressure can fall when that pressure is released. Gravitational energy is controlled by lowering the load or blocking it in place.

Where Multi-Energy Equipment Trips Facilities Up

The single-source machine is the easy one. A bench grinder with one electrical disconnect is straightforward. The equipment that causes problems is the machine with two, three, or four energy sources, where it’s easy to lock out the obvious one and stop there.

When we walk a facility, the most common gap we find is a procedure that opens the electrical disconnect and calls it done, while the machine still holds compressed air or hydraulic pressure. One food-production client described their equipment exactly this way: a CIP system, a boiler, a filler, and a packer line, “all of which require air and electrical.” Each of those machines needs both energy sources isolated, in the right order, or the procedure doesn’t actually make the equipment safe.

Sequence matters with multi-energy equipment. If you cut electrical power before you bleed the air, you can’t run the controls to confirm the air has actually released. The order of isolation is part of what makes a procedure work, and it’s one of the things our team checks on every machine with more than one energy source.

This is why generic, one-size-fits-all templates fall short. Each machine has its own combination of energy sources, isolation points, and shutdown order. That’s the entire purpose of equipment-specific lockout/tagout procedures: documenting every energy source on every machine, with photos showing exactly where each one is isolated.

Lockout Devices and Methods by Energy Type

Different energy sources call for different isolating devices. Cal/OSHA §3314 requires that equipment with lockable controls be physically locked out, not just tagged. (Tagout alone is not enough for equipment that can be locked.) When a tag is used, §3314(e) requires it to be non-reusable, attachable by hand, self-locking, and able to withstand at least 50 pounds of pull without releasing.

Common devices and where they apply:

• Padlocks and hasps. The base of any lockout. A hasp lets multiple workers each apply their own lock to the same isolation point, so the equipment stays locked until the last person is clear.
• Circuit breaker and disconnect lockouts. Clamp over a breaker or switch to hold it in the off position for electrical isolation.
• Plug lockouts. Enclose a cord-and-plug connection so the plug can’t be reinserted on smaller equipment.
• Valve lockouts. Cover or pin gate, ball, and butterfly valves in the closed position for pneumatic, hydraulic, steam, gas, and chemical lines.
• Blind flanges and line blanks. Physically block a pipe for high-hazard chemical or steam lines where a closed valve isn’t enough.
• Blocks, pins, and chains. Physically restrain gravitational and mechanical energy: blocking an elevated die, pinning a ram, or chocking a load that could move.

Common California Equipment and Its Energy Profile

The equipment list below reflects the machines we most often document in California manufacturing, food production, and processing facilities. Use it as a starting point for thinking about what each of your machines actually holds.

Most facilities have a mix of single-energy and multi-energy machines. The job of a LOTO program is to document each one accurately, so any worker, including a new hire, can follow the procedure and isolate every source. For a plain-language starting point on the whole topic, see our guide to what lockout/tagout is.

Note that the energy sources on a given machine vary by make, model, and how it’s installed at your site. The table is a guide, not a substitute for surveying your own equipment. That survey is also part of meeting the broader Cal/OSHA framework, since LOTO training documentation should align with your facility’s IIPP recordkeeping under Title 8, Section 3203.

How Do You Lockout/Tagout a Forklift?

A forklift is a multi-energy machine, which surprises people who think of it as “just turn off the key.” Routine fueling or swapping a propane tank isn’t lockout/tagout. Maintenance and repair are.

For an electric forklift, you control the electrical energy by disconnecting the battery, not just removing the key. The battery is a live energy source as long as it’s connected. You also account for the hydraulic and gravitational energy in the mast and forks: lower the forks fully or block them so they can’t drop while someone works underneath.

For an internal-combustion forklift, the steps shift to isolating the fuel source and accounting for the same hydraulic and gravitational energy in the lift mechanism. Either way, only a trained authorized employee should perform the lockout, and the specific steps belong in a written, equipment-specific procedure kept with the machine.