Adjustments on power machines should only be made when the machine is completely powered off, isolated from its energy source, and locked out, with very few exceptions. Federal workplace safety rules require this because machinery is the single largest source of severe workplace injuries, accounting for 25% of all serious injury reports to OSHA in 2022 and 2023. The narrow exceptions that allow adjustments while a machine is still running come with strict conditions.
The Default Rule: Power Off First
OSHA’s lockout/tagout standard (1910.147) is the governing rule. It requires that before any employee performs servicing or maintenance on a machine where unexpected startup or energy release could cause injury, the machine must be isolated from its energy source and rendered inoperative. This applies to electrical, hydraulic, pneumatic, mechanical, thermal, and chemical energy sources.
The required sequence is specific. First, the authorized worker must understand the type and magnitude of energy the machine uses and how to control it. Then the machine is shut down using its normal stopping procedure. Next, all energy-isolating devices are physically located and operated to disconnect the machine from power. Finally, a lockout or tagout device is applied so no one can restart the machine while work is being done. Only after verifying the machine is truly de-energized can adjustments begin.
The Minor Servicing Exception
There is one important exception. OSHA allows certain minor servicing activities to be performed during normal production operations without full lockout/tagout, but only when all three of these conditions are met simultaneously:
- Routine: The task is part of a regular, basic course of procedure, not a one-off repair.
- Repetitive: It’s repeated regularly as part of the production process or cycle.
- Integral: It’s inherent to and performed as part of the production process itself.
Even when all three conditions are met, the employer must provide alternative protective measures that give workers effective protection. Simply meeting the three criteria doesn’t mean you can work on an energized machine with no safeguards. Examples of qualifying tasks might include minor tool adjustments, lubrication, or clearing small jams that happen frequently during a production cycle. A major repair, an unusual fix, or anything that takes you outside the normal production routine does not qualify.
Why This Matters: The Injury Numbers
Getting caught in or compressed by equipment or objects was the most commonly reported type of severe injury in 2022 and 2023, with 4,158 reports making up 23% of all severe injuries logged by OSHA. Real cases illustrate why these rules exist. In one incident, a worker helping to grease the gears on a machine had their index finger degloved by a conveyor belt. In another, a worker trying to unjam a cocoa shell processing machine lost parts of two fingers when their hand was caught. Both scenarios involved tasks that might seem routine but exposed workers to moving machine parts.
When Interlocks Must Be Bypassed
Some machines have safety interlocks, which are devices that automatically shut the machine down or prevent operation when a guard is opened or a worker enters a hazardous zone. Occasionally, calibration or troubleshooting requires temporarily bypassing these interlocks. This is a high-risk activity that should follow a formal written permit process.
A bypass permit should specify the exact date range the bypass is in effect, a description of the interlock being disabled and why it exists, the hazards created by the bypass, and what compensating safety measures will replace the interlock’s protection during that time. The approval level should match the risk involved, and all affected workers need to be informed that the bypass is active, typically through a posted notice at the workstation. Once the work is done, the interlock must be restored immediately.
The core principle is that the interlock was installed for a reason. Before bypassing it, workers and supervisors need to confirm exactly what hazard it protects against and ensure other safeguards are adequate to cover the gap.
Safe Adjustment Procedures Step by Step
Whether you’re performing a full lockout or working under the minor servicing exception, certain preparation steps apply every time. Before touching the machine, put on all required personal protective equipment. Make sure the work area is well-lit, dry, and clean. Remove loose clothing, jewelry, or anything that could get caught in moving parts. Check that all guards are in place and undamaged. If a guard is defective or missing, do not use the machine and report it to your supervisor.
If a lockout or tagout device is already in place on the machine, you may not remove it and you may not operate that machine. Only the person who applied the lock, or a qualified individual following a specific removal procedure, can take it off.
During any adjustment, never remove a guard while the machine is running. If you lose focus or become distracted, stop work immediately. After finishing, perform basic maintenance checks and report any problems so the machine can be repaired before the next person uses it.
Who Is Authorized to Make Adjustments
Only qualified personnel may install, adjust, or repair equipment. OSHA’s energy control standard requires employers to train workers in three categories: authorized employees who actually perform the lockout and do the work, affected employees who operate the machine or work nearby, and other employees who may be in the area. Each group needs different training, but no one should be adjusting a power machine without proper authorization and a clear understanding of the energy control procedures for that specific piece of equipment.
Employers are also required to conduct periodic inspections of their energy control procedures to make sure they’re being followed correctly. If you’re unsure whether a particular adjustment requires full lockout or falls under the minor servicing exception, the safest answer is to lock it out. The few minutes it takes to de-energize a machine are insignificant compared to the severity of injuries that occur when things go wrong.