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726 Introduction to Machine Guarding
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Sources of Hazardous Energy During Maintenance and Repair

In situations where the maintenance or repair worker would necessarily be exposed to electrical elements or hazardous moving machine parts in the performance of the job, all power sources must be shut off and locked out before work begins.

Image of employee inspecting lockout tagout device
All power sources must be shut off and locked out before maintenance work begins if workers are exposed to electrical elements or hazardous moving machine parts.

Warning signs or tags are inadequate insurance against the untimely energizing of mechanical equipment

Thus, one of the first procedures for the maintenance person is to disconnect and lock out the machine from all of its power sources, whether the source is electrical, mechanical, pneumatic, hydraulic, or a combination of these. Energy accumulation devices must be "bled down."

Electrical Energy Hazards

Unexpected energizing of electrical equipment that can be started by automatic or manual remote control may cause electric shock or other serious injuries to the machine operator, the maintenance worker, or others operating adjacent machines controlled by the same circuit.

For this reason, when maintenance personnel must repair electrically powered equipment, they should open the circuit at the switch box/circuit breaker panel and padlock the switch (lock it out) in the "off" position.

This switch should also be tagged with a description of the work being done, the name of the maintenance person, and the department involved. When more than one worker is to be engaged in the servicing/maintenance function a lockout hasp may be used to which each worker affixes a personal lock.

Knowledge Check Choose the best answer for the question.

6-3. What must occur if a maintenance worker could be exposed to electricity or hazardous moving machine parts?