most people think of uncontrolled hazardous energy, they immediately
think of electricity, but there are other sources of energy
that can be just as hazardous. These energy sources include
thermal, chemical, pneumatic, hydraulic, mechanical, and gravitational.
It is important to remember that all sources of energy have
the potential to unexpectedly startup, energize, or release.
Because of this, they must be identified and locked, blocked,
or released before servicing or maintenance is performed on
machinery or equipment.
initial survey should be made to determine which switches,
valves, or other energy isolating devices apply to the equipment
being locked out. More than one energy source (electrical,
mechanical, hydraulic, pneumatic, chemical, thermal, or
others) may be involved.
questionable identification of sources must be cleared by
the employees with their supervisors.
lockout devices must be used only by trained individuals
All energy lockout devices must be adequately labeled or
marked to indicate their function. The identification includes
type and magnitude
system complexity requires it, a written sequence in checklist
form should be prepared for equipment access, lockout/tagout,
clearance, release, and startup.
or equipment shut down
all affected employees that a lockout is required and the
or equipment isolation
the equipment is operating, shut it down by the normal stopping
procedure (depress stop button, open toggle switch, etc.).
switches should never be pulled while under load, because
of the possibility of arcing or even explosion.
with a knowledge of equipment operation should be involved
with the shut down or restart procedures.
the switch, valve, or other energy-isolating device so that
the energy source(s), electrical, mechanical, hydraulic,
etc., is/are disconnected or isolated from the equipment.
energy, such as that in capacitors, springs, elevated machine
members, rotating flywheels, hydraulic systems, and air,
gas, steam, or water pressure, etc., must also be dissipated,
disconnected, or restrained by methods such as grounding,
repositioning, blocking, bleeding-down, etc.
fuses is not a substitute for locking out. A yanked fuse
is no guarantee the circuit is dead, and even if it was
dead, there's nothing to stop someone from unthinkingly
replacing the fuse.
Intermittently operating equipment such as pumps, blowers,
fans, and compressors may seem harmless when dormant. Don't
assume that because equipment isn't functioning, it will
stay that way.
and tag the energy isolating device with an assigned individual
lock, even though someone may have locked the control before
you. You will not be protected unless you put your own padlock
locks and tags must clearly indicate the identity of the
employee who applied the device. This provides positive
identification as to who is servicing the machinery and
equipment. The identification will also indicate who may
not have finished working in a multiple lockout/tagout situation.
locks and tags must be durable enough to withstand the environment
in which they will be used. Information on the locks and
tags must remain legible.
must be substantial enough to prevent removal without the
use of excessive force. Tags must be substantial enough
to prevent accidental or inadvertent removal.
locks and tags are to be standardized by either color, shape,
or size. Tags must have a standard print and format.
some equipment it may be necessary to construct attachments
to which locks can be applied. An example is a common hasp
to cover an operating button. Tags must be attached to the
energy isolating device(s) and to the normal operating control
and must be attached in such a manner as to preclude operation.
ensuring that no personnel can be exposed and as a check
on having disconnected the energy sources, operate the push
button or other normal operating controls to make certain
the equipment will not operate.
there is a possibility of re-accumulation of stored energy
to a hazardous level, verification of isolation must be
continued until the maintenance or repair is completed,
or until the possibility of such accumulation no longer
Return operating controls to neutral position after the
test. A check of system activation (e.g. use of voltmeter
for electrical circuits) should be performed to assure isolation.
The equipment is now locked out.
situations where the energy isolating device is locked/tagged
and there is a need for testing or positioning of the equipment/process,
the following sequence applies:
equipment/process of tools and materials.
the control of locks/tags according to established procedure.
with test, etc.
all systems and re-lock/re-tag the controls to continue
lockout or tagout devices are removed and energy is restored
to the machine or equipment, inspect the work area to ensure
that nonessential items have been removed and to ensure
that machine or equipment components are operationally intact.
work areas to ensure that all employees are in the clear.
affected employees that lockout/tagout devices have been
device must be removed from each energy-isolating device by
the employee who applied the device. The energy isolating devices
may be breakers, to restore energy to equipment.
Procedure involving more than one person
In the preceding steps, if more than one individual is required
to lock out equipment, each individual must place a personal
lock and tag on the group lockout device when he/she begins
work, and must remove those devices when he/she stops working
on the machine or equipment.
the power and stop the machine before servicing.
not clean, unplug, lubricate, adjust or repair any machine
while it is running, unless it is specifically recommended
in the service or owner's manual.
out the ignition and put a warning sign over the ignition
that tells everyone that you are working on the machine.
safety locks if the hydraulic cylinders are so equipped.
follow instructions in operator's manual for servicing hydraulic
off the engine, which powers the hydraulic pump.
implement to the ground or onto a solid support
the hydraulic lever back and forth several times to relieve
sure pneumatic accumulators are properly charged with the
proper inert gas
making adjustments or changing bits, disconnect the power
cord or you could accidentally touch the switch and be injured
when the tool starts.
all parts before working under a header. You may need to
raise the header to work on the cylinder and other parts.
Do not rely on the hydraulic system.
sure that the header lock or cylinder ram stop is fixed
in place or that proper blocking is in place.
The information and recommendations contained in this publication
are believed to be reliable and representative of contemporary
expert opinion on the subject material. The Farm Safety Association
Inc. does not guarantee absolute accuracy or sufficiency of
subject material, nor can it accept responsibility for health
and safety recommendations that may have been omitted due to
particular and exceptional conditions and circumstances.
Copyright © 2002 Farm Safety Association Inc.
22-340 Woodlawn Road West, Guelph, Ontario (519) 823-5600.
Disclaimer and Reproduction Information: Information in
NASD does not represent NIOSH policy. Information included in
NASD appears by permission of the author and/or copyright holder.