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SEMI S22-1103a © SEMI 2003, 2005 29 EXCEPTION: Equipment that meet s the wire bendi ng space requireme nts of NFP A 70 will also meet t h ese criteria. 17.10 Con ductors should be designed so that their curren t carrying…
SEMI S22-1103a © SEMI 2003, 2005 28
17.8.3 Cables that exit an electrical enclosure should be provided with adequate strain relief to ensure a mechanical
pull cannot dislodge the cable’s termination points. Compliance is verified by conducting a strain relief test in
accordance with ¶22.7 Strain Relief Test.
17.8.4 Flexible cables installed in or on machines should be protected to avoid insulation breakdown due to normal
operating conditions, single fault conditions, or foreseeable misuse. Some of the factors that should be considered
are:
a) moving machine parts,
b) brackets or cable guides on the machine,
c) abrasion,
d) exposure to liquids and gas,
e) exposure to radiation, and
f) temperature deviations.
NOTE 49: Natural rubber can be degraded by chemicals normally present in semiconductor fabrication facilities.
17.8.5 Where cables are subject to movement or are routed close to moving parts, precautions should be taken to
maintain a space of at least 25 mm (1 inch) between the moving parts and the cables. Where that distance is not
practicable, fixed barriers should be provided between the cables and the moving parts.
17.8.6 Where flexible conduit is adjacent to moving parts, the construction and supporting means should satisfy the
following:
a) It should prevent damage to the flexible conduit under normal operating conditions.
b) It should prevent damage to the insulation on the wire inside the conduit under single fault conditions.
17.8.7 Plug/Receptacle Combinations Where equipment is portable, connections to it should be made through a
polarized plug/receptacle combination.
17.8.8 Field wiring terminals connected at the time of installation should meet the wire bending space criteria in
Appendix 1, Tables A1-1 through A1-5.
EXCEPTION: Equipment that meets the wire bending space requirements of NFPA 70 will also meet these criteria.
17.8.9 Ducts and Connection Boxes
17.8.9.1 General Cables used in ducts should be suitably rated.
17.8.9.2 Fill of Ducts and Raceways The total cross sectional area of conductors permitted in raceways and ducts
should not exceed 50 percent of the interior cross sectional area of the raceway or duct.
NOTE 50: All other limiting factors for wires and cables should be taken into account. For example, temperature limitations may
reduce the number of allowable conductors.
17.8.9.3 Conduit and Fittings Non-flexible and flexible conduit and fittings should be suitable for the anticipated
conditions of use. Conduits should be securely held in place and supported at each end.
17.8.9.4 Fittings should be compatible with the conduit and appropriate for the application.
17.8.9.5 Fittings should be secured by a means that requires a tool to remove.
17.8.9.6 Conduit bends should be made in such a manner that the conduit should not be damaged and the internal
diameter of the conduit should not be effectively reduced.
17.8.9.7 Connection Boxes Connection boxes should provide protection against the intrusion of substances that
may damage insulation or may cause ground-faults.
17.8.9.8 The size of the connection box should be sufficient to allow dissipation of heat generated during normal
operation.
17.9 Subsystem Interconnection — Conductors that are connected between subsystems at the time of installation
should have wire bending space in accordance with ¶9.3.4 and phase identification in accordance with ¶9.1.6.3.
SEMI S22-1103a © SEMI 2003, 2005 29
EXCEPTION: Equipment that meets the wire bending space requirements of NFPA 70 will also meet these criteria.
17.10 Conductors should be designed so that their current carrying capacity is not impaired by mechanical,
chemical, or any other influences.
18 Electric Motors 186 Watts (1/4 Horsepower) and Larger
18.1 General The considerations provided in this section apply to electric motors and their electrical enclosures.
This includes the considerations for overcurrent protection. This section applies to AC and DC motors, 600 V or
less, 186 Watts (1/4 HP) and larger.
18.1.1 Remotely installed (for example, in a chase or sub-floor) motors should have a means of disconnecting all
unearthed conductors within sight of and not more than 3 meters (10 feet) travel distance of the motor.
18.1.2 Motors should be protected from ingress of liquids that may lead to increased risk of electric shock or fire.
The motor terminations to supply conductors should be in the motor housing or a separate enclosure provided for
this purpose.
NOTE 51: Assessment of risk generally involves consideration of single-fault tolerance (see ¶7.4 and ¶10.1).
18.1.3 The motor should be marked with the manufacturer’s name and part number. The motor should be marked
with directional arrows, if lack of this information could result in a safety concern.
NOTE 52: Phase identification is one method of identifying correct connection for motor direction.
18.1.4 Motors should be marked with their voltage, current and frequency rating.
EXCEPTION: This information can be provided in support documentation if it can be traced to the manufacturer’s
name and part number on the motor.
18.1.5 Under-voltage protection should be provided for all motors that could initiate hazardous equipment motion
when power is returned after an under-voltage condition.
18.2 Motor Mounting And Compartments
18.2.1 Each motor and its associated couplings, belts and pulleys, or chains, should be so mounted that they are
adequately guarded and may be serviced without putting personnel at risk of injury.
18.2.2 Construction should ensure proper cooling and that any rise in temperature remains within the limits of the
motors’ insulation class.
18.2.3 Applicable points on the motor should be accessible for lubrication, maintenance, and replacement.
18.2.4 Sufficient air circulation to maintain temperature within the motor rating should be provided.
18.3 Mechanical Brakes Where the operation of a mechanical brake increases the potential for entrapment or
other hazards, a method of brake release should be provided.
18.4 Protection of Motors
18.4.1 Overcurrent protection should be provided for motors. This protection should be sufficient to protect against
overcurrent conditions due to faults in the insulation, locked rotor, or overload conditions. The overcurrent
protection should open all unearthed conductors.
18.4.2 Where an overcurrent protection device may permit motor starting and still provide overload protection it
may be used for both purposes. However, a single device may not be suitable for both overcurrent and overload. In
such cases two separate devices should be used; one suitable device for short circuit and ground-fault protection and
the other for overload protection.
18.4.3 Overload protection should be in the form of one of the following:
a) overload relay,
b) thermal protection internal or external to the motor, or
c) impedance protection.
SEMI S22-1103a © SEMI 2003, 2005 30
18.4.4 The incoming circuit or feeder to power conversion equipment, included as part of an adjustable speed drive
system, should be based on the rated input to the power conversion equipment. Unless the power conversion
equipment is certified by an accredited testing laboratory to indicate that overload protection is included and suitable
for the motor, additional overload protection should be provided.
18.4.5 Over-speed protection should be provided in cases where over-speed may cause a hazardous condition.
19 Accessories and Lighting
19.1 Lighting Circuits
19.1.1 One conductor of all equipment lighting and maintenance lighting circuits should be bonded to the
equipment protective earthing system in accordance with ¶19.1.2 or 1¶9.1.3. See ¶17.6.3 for conductor
identification.
19.1.2 Where the lighting circuit is supplied by a separate transformer, the earthing should occur at the transformer.
19.1.3 When the protective conductor is connected to a screw-shell lamp holder, it should be connected to the screw
shell.
19.1.4 The conductors connected to stationary lights used as an integral part of the equipment should be suitable for
their application.
19.1.5 Equipment work lights should not contain switches or receptacles such that exposure to liquids or other
substances may increase the risk of electric shock or fire.
NOTE 53: Switches or receptacles should be located where liquids or other substances will not increase the risk of electric
shock.
19.2 Attachment Plugs and Receptacles
19.2.1 Attachment plugs and receptacles should be rated and labeled for the applied voltage and current.
19.2.2 Where used in circuits of 300 Volts or more, attachment plugs and receptacles should be rated for the
application (load break or no-load break), and constructed to contain any arc generated when a connection is made
or broken.
19.2.3 Attachment plugs and receptacles should be designed or installed to prevent the ingress of substances that
may increase the risk of electric shock or fire.
19.2.4 Receptacles internal to the electrical enclosure should be permitted only for maintenance equipment or AC
power distribution within the enclosure to assemblies designed and approved for cord-and-plug connection. See
¶17.3 for more details regarding receptacles.
20 Markings
20.1 General Hazard alert signs, nameplates, markings, and identification plates should have sufficient
durability to withstand the anticipated physical environment where the equipment will be installed.
20.2 Hazard Alert Signs Enclosures should be labeled to inform the end user of the hazards that they enclose.
These labels should comply with SEMI S1.
EXCEPTION: This labeling is not necessary where the enclosures are interlocked with non-defeatable interlocks to
disconnect the hazards in question.
20.3 Functional Identification Control devices, visual indicators, and displays should be clearly and durably
marked with their functions either on, or adjacent to, the items. Refer to ¶14.2.2, Markings.
20.4 Equipment Nameplate A permanent nameplate should be attached to the main electrical enclosure or
equipment where it is plainly visible after installation. This nameplate should include the following information:
a) the manufacturer’s name and address,
b) the equipment name, model, and serial number,
c) supply voltage,