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SEMI S21-1103 © SEMI 2003 7 9 EEW at Hazardous Voltage or Energy Lev els 9.1 Hazardous electrical en ergy should be isolated whenever it is possible to perform the work with the equipment non-energize d. 9.2 When electri…
SEMI S21-1103 © SEMI 2003 6
8 Control of Hazardous Energy
NOTE 15: Control of hazardous energy is commonly known
as lock and tag or Lockout/Tagout. US OSHA regulation: 29
CFR 1910.147 is one location where detailed information can
be found.
8.1 Hazardous Energy Control (lockout/tagout) is a
method for isolating sources of hazardous energy from
equipment and protecting workers from accidental
release of the energy.
8.2 Suppliers should identify all tasks that could be
affected by hazardous energy, (e.g., electrical,
chemical, mechanical, hydraulic, pneumatic, stored,
gravity or thermal) and should provide procedures for
effectively isolating such energy and safely restoring
the energy after performing each work task.
8.3 Safe De-Energized Work Procedures
8.3.1 Preparation
NOTE 16: This list is not intended to be in any specific order
and the order may be changed to reflect individual conditions.
a. Identify the task to be performed.
b. Identify all energy sources and the location of the
means of isolation for each source.
c. Notify potentially affected persons that the work
will be performed.
d. Locate hazardous energy control procedures for the
specific system and task.
e. Shut down equipment using normal shut down
procedures.
f. Isolate all appropriate energy sources in the order
and manner specified in the procedures.
NOTE 17: Certain procedures may require modification to
account for factory-located energy isolation devices and to
meet local regulatory requirements.
g. For electrical energy, turn off the power at the
appropriate disconnection point.
NOTE 18: If regulations have allowed multiple electrical
energy sources, (e.g., main power, emergency power, UPS
power) all sources of power must be identified. Each source
that may expose the worker should be isolated to ensure safe
working conditions.
h. Verify absence of hazardous voltage at the
equipment side of the disconnecting mechanism with an
appropriate test device.
• The test device should be checked for correct
operation before and after testing for the presence
of hazardous electrical energy.
i. Ensure that all energy is at zero state and that any
capacitors or other electrical energy storage devices are
fully discharged or isolated.
j. Follow any special steps needed to eliminate stored
energy (e.g., liquid or gas pressure, capacitors,
compressed springs, support of a raised mass).
k. Each person performing work should apply a
locking device (under exclusive control of the worker)
and a tag to each isolated energy source.
NOTE 19: Some jurisdictions allow for group lockout
capability. Entities creating procedures and persons
performing lockout should understand the procedures for the
location.
l. Verify that energy is no longer present (e.g., check
pressure, presence of liquid, weight, temperature)
8.3.2 Performing Work Tasks
8.3.2.1 Work may only be performed by persons who
are trained to work on the specific equipment.
8.3.2.2 De-energized work may only occur after the
person has isolated the energy and applied a lock and
tag to the energy isolation device.
8.3.2.3 Work continuing past shift change should be
provided with special lockout transfer procedures (that
are usually controlled by the user) to ensure locks are
applied by the workers on the new shift and that
workers on then previous shift have removed their
locks.
8.3.3 Restoration of Energy
8.3.3.1 Remove all hand tools, parts and other
miscellaneous items may have been inadvertently left in
the area during the work.
8.3.3.2 Ensure all safety devices have been restored.
8.3.3.3 Notify all personnel who could be affected by
the potential hazard.
8.3.3.4 Remove energy isolation devices (e.g., locks,
tags blinds, barriers) in the order specified in the task
procedures.
8.3.3.5 After verifying that all persons are clear, restart
the system.
8.3.3.5.1 Apply energy in the proper sequence for safe
restart (e.g., power to interlocks and controls before
main energy, power to interlocks before chemical re-
pressurization).
8.3.3.6 Verify equipment is operating properly.
8.3.3.7 Reset all outer enclosure interlocks and secure
outer enclosures.
SEMI S21-1103 © SEMI 2003 7
9 EEW at Hazardous Voltage or Energy Levels
9.1 Hazardous electrical energy should be isolated
whenever it is possible to perform the work with the
equipment non-energized.
9.2 When electrical energy cannot be isolated due to
the type of work to be performed (e.g., trouble-
shooting, power supply adjustment), suppliers should
identify all tasks that include electrical-energized work
and should provide procedures for safely accomplishing
such work.
9.2.1 Facility operators should verify, modify if
necessary, and approve procedures before EEW is
performed at the facility.
NOTE 20: Appropriate levels of PPE for EEW can only be
calculated with knowledge of the energy available from the
source (e.g., sub-station, transformer) that provides power
from the facility to the equipment circuit.
9.3 EEW or Working on Energized Electrical Circuitry
9.3.1 Supplier should notify the user of any EEW that
may be required.
NOTE 21: Routine testing of circuits may be included in the
definition of EEW in some circumstances and in some
jurisdictions.
9.3.1.1 Two or more qualified persons should perform
EEW, except for the routine testing of circuits.
9.3.1.2 One worker should always have access to and
be ready to de-energize the system by operating the
appropriate disconnecting device.
NOTE 22: Some jurisdictions or users may require persons to
be trained in emergency rescue procedures such as cardio
pulmonary resuscitation (CPR) electrical shock first-aid, and
extracting a person from an energized circuit.
9.3.1.3 EEW should only be performed by workers
wearing appropriate electrical PPE and natural fiber
clothing for protection against shock, arc, flash, or burn.
NOTE 23: Electrical PPE manufacturers have been testing
certain models of natural fiber or electrical protective
synthetic fiber (e.g., Monofilament Nomex) for clean room
purposes, however, supplier personnel and users should
coordinate the use of clothing that is acceptable in the specific
factory.
9.3.1.3.1 Clothing made from synthetic materials such
as acetate, nylon, polyester, or rayon, either alone or in
blends with cotton, should not be worn for EEW at
hazardous energy levels where the exposure for arc,
flash or burn exists; because it can melt and therefore
fail to provide adequate protection.
NOTE 24: Normal clean room clothing is made from
synthetic fabrics and caution should be taken to provide
adequate protection.
NOTE 25: A Hazard/risk analysis may be used to determine
available fault current and incident energy level in J/cm
2
.
These calculated levels establish the level of natural fiber,
calorie-rated flame resistant clothing and electrical PPE
necessary for protection. Calculation formulas and
hazard/risk analysis methods are available in documents such
as ANSI/NFPA 70E.
9.3.1.4 Metal jewelry (e.g., such as watches, rings,
metal framed eyeglasses, and body-piercing jewelry)
should be removed during EEW.
9.3.1.5 During EEW, access to the immediate work
area should be restricted from unqualified workers by
the use of barricades, safety signs, safety cones, safety
tape or a human guardian.
9.4 Safe EEW procedures should be provided by
supplier and should include the following:
a. Verification of valid reasons for performing the
work energized.
b. Identify electrical energy sources and the location
of the means of isolation for each source.
NOTE 26: Identification is required to ensure that workers
know how to remove energy if an emergency develops during
the work task.
c. When the hazard is remote from the equipment
controls, the warning should also be provided at the
point of the hazard.
d. When the EEW is complete, workers should
restore the equipment to its original state and ensure
that all safeguards are restored and interlocks are
functioning properly.
10 Radiation-Producing Equipment
10.1.1 Ionizing Radiation
10.1.1.1 Initial radiation surveys should be performed
as required by regulations to verify that radiation
shielding is installed.
10.1.1.1.1 Additional radiation surveys should be
conducted following maintenance or service tasks to
ensure shielding remains in place, and is effective.
10.1.1.2 Access of unauthorized persons, to working
areas where there is a risk of exposure to hazardous
levels of radiation, should be restricted.
10.1.1.3 If work associated with radiation is required,
the workers should be trained on the hazard
characteristics and appropriate protection measures,
including safe handling, use, and shielding.
NOTE 27: Certification of the people performing the work
may be required, depending on the work to be performed or
the type of radiation.
SEMI S21-1103 © SEMI 2003 8
10.1.1.4 Prior to performing work, workers should
reconfirm the instructions and other related documents
to avoid any misunderstanding of the work procedure.
10.1.1.5 An appropriate method of monitoring the
amount of worker exposure to radiation during work
with ionizing radiation should be considered.
10.1.2 Non-Ionizing Radiation
10.1.2.1 When performing work with potential
exposure to non-ionizing radiation, the potential
exposure should be evaluated and appropriate
protection provided. See SEMI S2 as a technical guide.
10.1.3 Lasers
10.1.3.1 Work on lasers should be performed with the
laser de-energized whenever possible.
10.1.3.2 Workers performing work on laser equipment
should be trained in the hazards and proper work
procedures.
10.1.3.3 During work on other than Class 1 or Class 2
laser equipment, access to the area where unauthorized
personnel can be exposed to energized laser beams
should be controlled with a safety enclosure or other
appropriate method.
NOTE 28: Laser classes greater than Class 1 and Class 2
require PPE when entering the path of an energized laser.
10.1.3.3.1 Suppliers should consider warning labels for
Class 2 laser equipment to ensure workers do not
inadvertently enter the laser path.
10.1.3.4 When working on an opened laser, protective
measures (which may include PPE) should be taken for
the appropriate hazards and level of risk.
10.2 Extreme Temperatures
10.2.1 When performing work with potential exposure
to hazardous surface temperatures, the potential
exposure should be evaluated, and appropriate
protection provided, or the temperature adjusted to a
safe level. See SEMI S2 for acceptable temperature
ranges.
11 Physical Hazards
11.1 Work at Elevated Heights
NOTE 29: Work at extreme heights may require specific
training or specially certified personnel. For example, Japan
Labor Safety Regulations require workers working at five
meters or higher to be a nationally certified chief worker.
11.1.1 If the work at an elevated position, such as the
end of a platform or through an opening, poses a fall
hazard, the area should be guarded with a fence,
handrail, or cover, or fall protection should be worn.
11.1.2 When installing components or assemblies at
heights, protective measures to prevent falling objects
should be implemented. Heavy components or
assemblies should be lifted into position with
ergonomically acceptable lifting equipment.
11.1.3 Work on a Stepladder
NOTE 30: Ladders must be approved for the jurisdiction in
which they are used, if applicable.
11.1.3.1 Stepladders should be stored away from
chemicals and contaminants.
NOTE 31: Regulations related to ladder materials of
construction acceptability may affect use of certain ladders in
areas where chemicals are used or where the ladder is used for
potentially energized electrical work.
11.1.3.2 Stepladders should be inspected to verify that
they are in good condition. If they are not, the
stepladders should be taken out of service until they are
repaired or replaced. Rungs should be inspected to
ensure that they are kept free from fluids and debris.
11.1.3.3 Only one person should be ascending or
descending a stepladder at any time even if steps are
provided on both sides of the ladder.
11.1.3.4 When ascending or descending, workers
should face the stepladder, use at least one hand to
grasp the stepladder and not carry any object that
interrupts the worker’s view.
11.1.3.5 Stepladders should be used fully extended and
with legs locked. Unstable positions such as work on
top two steps, work which requires the torso to extend
beyond the rails, and work which requires standing on
tiptoes or a single foot should be avoided.
11.1.3.6 Work should not be performed below the
stepladder when in use.
11.2 Protection Against Falling Objects
11.2.1 If the work involves hazards from flying or
falling objects, one or more of the following safety
measures should be implemented as appropriate:
• Control approach to the area
• Install a safety net
• Wear a hardhat
• Use measures to secure tools and parts used for the
work
11.3 Visual Hazard Warnings
11.3.1 Barrier tape or another equivalent method to
designate work areas involving fall hazards should be
used, in addition to appropriate signage such as