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SEMI S22-1103a © SEMI 2003, 2005 10 8.4.3 Components should be securely mounted a ccording to the conditions of their certification, if applicable, and their manufact urer’s instructions. 8.5 Electrical Supply 8.5.1 The …
SEMI S22-1103a © SEMI 2003, 2005 9
a) taking all reasonable steps to avoid high temperatures which might cause ignition;
b) controlling the position of combustible materials in relation to possible ignition sources;
c) limiting the quantity of combustible materials used;
d) using barriers, if necessary, to limit the spread of fire within the equipment beyond the immediate vicinity of the
ignition source; and/or
e) using suitable materials for the outer fire enclosures of the equipment.
NOTE 14: SEMI S14 may also be used for guidance on fire risk mitigation.
NOTE 15: Some fire retardant components or materials may be restricted or banned in certain jurisdictions.
7.9 Equipment should be designed to prevent injury due to excessive (high or low) temperatures of parts; to ensure
that the equipment is mechanically stable and structurally sound; to avoid the presence of operator accessible sharp
edges and points; and to provide adequate guarding or safety interlocking of hazardous moving parts.
7.10 Materials used in the construction of equipment should be selected and arranged so that they may be expected
to perform in a reliable manner, without a risk of energy hazard or electric shock developing, and such that they
would not contribute significantly to the development of a significant fire hazard.
NOTE 16: Some electrical components such as relays, electrolytic capacitors, batteries, solder, cathode ray tubes, finished
chassis, fluorescent lights and connectors may contain materials that are restricted or banned in certain jurisdictions.
8 General Considerations
8.1 The risks associated with the electrical design, construction, and operation of the equipment should be
considered as part of the overall safety assessment of the equipment. This assessment should include a fault analysis
with consideration given to, but not limited to, electric shock or fire and failures of components, subsystems, and
systems.
8.2 The following are some of the types of faults that should be considered:
a) faults and failures in the equipment’s circuits, and
b) possible human error associated with operator, maintenance, and service activities.
NOTE 17: This is not intended to be a comprehensive list of all possible types of faults.
8.3 The order of precedence for resolving identified hazards and satisfying equipment safety considerations should
be as follows:
a) design to eliminate hazards,
b) incorporate safety devices,
c) provide hazard alerts or warning signals, and finally
d) develop administrative procedures and training (administrative procedures may include the use of personal
protective equipment).
A combination of these approaches can also be used.
NOTE 18: See SEMI S2 for additional information.
8.4 Electrical Components
8.4.1 Where failure of components and assemblies could result in an unacceptable increase in risk of electric shock,
fire, or personnel injury, those components and assemblies should be certified by an accredited testing laboratory
and used in accordance with the manufacturer’s specifications and conditions of the certification, or otherwise
evaluated to the relevant component standard(s). This applies to components that handle hazardous voltage or
hazardous electrical power or are used in a safety circuit.
NOTE 19: Reference SEMI S2 for discussions of acceptable risk.
8.4.2 Components should be provided with overcurrent protection in accordance with §11.
SEMI S22-1103a © SEMI 2003, 2005 10
8.4.3 Components should be securely mounted according to the conditions of their certification, if applicable, and
their manufacturer’s instructions.
8.5 Electrical Supply
8.5.1 The equipment should be designed to operate safely when connected to its specified electrical supply.
8.5.2 Interruptions in the facilities electrical supply should not lead to an increased risk of fire, electric shock, or
other hazardous conditions.
8.6 Un-interruptible Power Supplies (UPS) This subsection applies to UPSs with outputs greater than 30 Volts
rms, 42.4 Volts peak, 60 Volts DC or 240 Volt-Amperes (VA). Whenever a UPS is provided with the equipment, its
location and wiring should be clearly described within the relevant manufacturer supplied documentation that covers
installation and maintenance.
8.6.1 Power from the UPS should be interrupted when any of the following events occur:
a) the emergency off actuator (EMO button) is pushed; or
b) the equipment main disconnecting means is opened.
EXCEPTION: Upon emergency off (EMO) activation, the UPS may continue to supply power to the EMO circuit,
safety related devices, and data/alarm logging computer systems as described in the exception clauses of ¶13.3.3.
8.6.2 The UPS may be physically located within the footprint of the equipment provided that the UPS is within its
own electrical enclosure, which may be the enclosure provided with the UPS and considered in the certification of
the UPS. The UPS circuits may also be supplied from a facility source outside of the equipment served. If this is
the case, then all the considerations discussed for facilities main disconnecting means in §9 should be taken into
account for power supplied to the UPS circuits.
8.6.3 The UPS should be certified by an accredited testing laboratory.
8.6.4 The UPS wiring and terminals should be identified as “UPS Supply Output”, or equivalent, at each connection
point where the UPS wiring may be disconnected.
8.7 Operating Environment — The electrical equipment should be suitable for the environment in which it is
intended to be used.
8.8 Electromagnetic Compatibility (EMC) A system malfunction, as a result of the presence of anticipated
electromagnetic disturbances that will be present in the end use environment, should not result in an unacceptable
risk. Products that are compliant with either SEMI E33 or the EMC Directive (89/336/EEC) are considered to be
compliant with this criterion.
8.9 Contaminants
8.9.1 Electrical equipment should be adequately protected against the entrance of solid bodies and liquids likely to
be present that may increase the risk of electric shock or fire as a result of a single-point failure or reasonably
foreseeable operational error.
8.9.2 Electrical insulation should be protected against chemical environments that may lead to deterioration, or be
capable of withstanding the environments to which it will be exposed.
8.10 Ionizing and Non-ionizing Radiation Personnel should be adequately protected against the hazards
associated with ionizing and non-ionizing radiation. Compliance to the ionizing and non-ionizing radiation sections
of SEMI S2 serves as verification of compliance.
8.11 Vibration, Shock, and Bump Protection should be provided against likely unsafe consequences from the
effects of vibrations, shocks and bumps caused by operation of the equipment, or disturbances of this type that will
be present in the semiconductor manufacturing, testing, and assembly environment.
NOTE 20: See the SEMI S2 seismic section for considerations.
8.12 Transportation and Storage Packing for shipment should prevent damage from humidity, vibration, and
shock that may affect the safety of the equipment.
SEMI S22-1103a © SEMI 2003, 2005 11
EXCEPTION: Installation considerations for checking safety related aspects of the system that may be impacted
during transportation and storage may be used instead of the packing stipulations of ¶8.12.
8.13 Provisions for Handling Provisions for lifting and handling sub-systems that may cause injury when moved
or lifted during maintenance or service should be provided and documented in the system manuals. See SEMI S8 for
further information.
8.14 Lockout (electrical energy isolation) — Lockable energy isolation devices should be designed into equipment
to provide for safety during service and maintenance tasks. Where it is expected that it will be necessary or
beneficial to work on separately operable parts of the equipment, a separate lockable energy isolation device may be
provided for each such part.
8.15 Suspension of Safeguards General energy isolation, local energy isolation, or safe work procedures should
be used when there is a suspension of safeguards. These procedures should be defined in the maintenance manual.
9 Facilities Electrical Connection
9.1 Incoming Supply Conductors
9.1.1 Equipment should be designed to receive incoming electrical power from the facility to a single feed location
which terminates on the specified main disconnecting means. This main disconnecting means, when opened, should
remove all electrical power in the equipment from the load-side of the main disconnecting means.
EXCEPTION 1: Equipment with more than one electrical feed should be provided with provisions for energy
isolation (“lockout”) for each feed and be marked with the following text, or the equivalent, at each main
disconnecting means: “WARNING: Risk of Electric Shock or Burn. Disconnect all [number of feed locations]
sources of supply prior to servicing.”
EXCEPTION 2: Multiple units mounted separately with no shared hazards and without interconnecting circuits
with hazardous voltages, energy levels, or other potentially hazardous conditions may have: separate sources of
power and separate supply circuit main disconnecting means; or separate EMO circuits, where all the above are
clearly identified.
NOTE 21: If general lockout cannot be performed for a specific maintenance or service task the guidance in Section 8.15 should
be followed.
9.1.2 Field installed supply conductors should be connected directly to the main disconnecting means with no
connection to terminal blocks or other devices.
EXCEPTION: This does not apply where the plug of a cord is the main disconnecting means. However, if the plug
of the cord is not the main disconnecting means then field installed supply conductors should be connected directly
to the main disconnecting means with no connection to terminal blocks or other devices.
9.1.3 Terminals with hazardous potentials present after the main disconnecting means is placed in the “Off”
isolation position should be identified with an appropriate hazard warning label. The label should be placed inside
the electrical enclosure adjacent to the terminals.
9.1.4 The supply overcurrent protection should be rated adequately to protect components connected to the supply
circuit that do not otherwise have adequate overcurrent protection.
9.1.5 The equipment should be provided with main overcurrent protection devices rated with an interrupting
capacity of at least 10,000 rms symmetrical amperes interrupting capacity (AIC) for circuits rated 240VAC or less,
and at least 14,000 rms symmetrical amperes interrupting capacity (AIC) for circuits rated more than 240VAC.
EXCEPTION 1: Cord connected single phase equipment, rated no greater than 2.4 kVA, may have overcurrent
protection devices with an interrupting capacity of at least 5,000 rms symmetrical amperes interrupting capacity.
When this exception is used, the installation manual should inform the user of the lower AIC protection provided by
the equipment.
EXCEPTION 2: An equipment subsystem (e.g. mini-environment ventilation) rated no greater than 2.4 kVA, may
have overcurrent protection devices with interrupting rating of at least 5,000 rms symmetrical amperes interrupting
capacity (AIC).