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SEMI S2-0703a E © SEMI 1991, 2004 16  the main circui t breaker is opened. EXCEPTION: Up on EMO activation, the UPS m ay supply power to the EMO circuit, safety related devices, and da ta/alarm l ogging computer system …

SEMI S2-0703a

NOTE 41: With the exception of implementation of ground

fault protection, shunt trip units that require power to trip

(actuate) are not recommended to be used in a safety control

circuit, because they are not fail-safe.

13.4.4 Electrical wiring for power circuits, control

circuits, grounding (earthing) and grounded (neutral)

conductors should be color coded according to

appropriate standard(s) per Section 13.4, or labeled for

easy identification at both ends of the wire. Where color

is used for identification, it is acceptable to wrap

conductor ends with appropriate colored tape or

sleeving; the tape or sleeving should be reliably secured

to the conductor.

EXCEPTION 1: Internal wiring on individual

components, e.g., motors, transformers, meters,

solenoid valves, power supplies.

EXCEPTION 2: Flexible cords.

EXCEPTION 3: Nonhazardous voltage multi-conductor

cables (e.g., ribbon cables).

EXCEPTION 4: When proper color is not available for

conductors designed for special application (e.g., high-

temperature conductors used for furnaces and ovens).

13.4.5 Grounding (earthing) conductors and connectors

should be sized to be compatible in current rating with

their associated ungrounded conductors according to

appropriate standard(s) per Section 13.4.

13.4.6 Electrical enclosures should be suitable for the

environment in which they are intended to be used.

13.4.7 Enclosure openings should safeguard against

personnel access to uninsulated energized parts. (Refer

to Appendix 1 for examples of openings for protection

against access from operators.)

13.4.8 Top covers of electrical enclosures should be

designed and constructed to prevent objects from

falling into the enclosures. (Refer to Appendix 1 for

examples of acceptable top enclosure openings.)

13.4.9 The current interrupting capacity (also known as

amperes interrupting capacity, or AIC) of the

equipment main disconnect should be identified in the

facility installation and maintenance manuals.

13.4.10 The equipment should be provided with main

overcurrent protection devices and main disconnect

devices rated for at least 10,000 rms symmetrical

amperes interrupting capacity (AIC).

NOTE 42: Some facilities may require higher AIC ratings

due to electrical distribution system design.

EXCEPTION: Cord- and plug-connected single phase

equipment, rated no greater than 240 volts line-to-

line/150 volts line-to-ground and no greater than 2.4

kVA, may have overcurrent protection devices with

interrupting capacity of at least 5,000 rms symmetrical

amperes interrupting capacity (AIC).

13.4.11 Equipment should be designed to receive

incoming electrical power from the facility to a single

feed location that terminates at the main disconnect

specified in Section 13.4.9. This disconnect, when

opened, should remove all incoming electrical power in

the equipment from the load side of the disconnect. The

disconnect should also have the energy isolation

(“lockout”) capabilities specified in Section 17.

EXCEPTION 1: Equipment with more than one 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 disconnect:

“WARNING: Risk of Electric Shock or Burn.

Disconnect all [number of feed locations] sources of

supply prior to servicing.” It is preferred that all of the

disconnects for the equipment be grouped in one

location.

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 disconnect means, if they are clearly

identified; or

 separate EMO circuits, if they are clearly

identified.

13.4.12 A permanent nameplate listing the

manufacturer’s name, machine serial number, supply

voltage, phase, frequency and full-load current should

be attached to the equipment where plainly visible after

installation. Where more than one incoming supply

circuit is to be provided, the nameplate should state the

above information for each circuit.

NOTE 43: Additional nameplate information may be

required depending on the location of use.

13.5 Uninterruptable Power Supplies (UPSs) — This

section applies to UPSs with outputs greater than: 30

volts rms, 42.4 volts peak; 60 volts dc; or 240 volt-

amps.

13.5.1 Whenever a UPS is provided with the

equipment, its location and wiring should be clearly

described within the installation and maintenance

manual.

13.5.2 Power from the UPS should be interrupted when

any of the following events occur:

 the emergency off actuator (button) is pushed; or

 the main equipment disconnect is opened; or

SEMI S2-0703a

 the main circuit breaker is opened.

EXCEPTION: Upon EMO activation, the UPS may

supply power to the EMO circuit, safety related

devices, and data/alarm logging computer systems as

described in the exception clauses of Section 12.2.

13.5.3 The UPS may be physically located within the

footprint of the equipment provided that the UPS is

within its own enclosure and is clearly identified.

13.5.4 The UPS should be certified by an accredited

testing laboratory and be suitable for its intended

environment (e.g., damp location, exposure to

corrosives).

13.5.5 The UPS wiring should be identified as “UPS

Supply Output” or equivalent at each termination point

where the UPS wiring can be disconnected.

13.6 Electrical Safety Tests

13.6.1 Equipment connected to the facility branch

circuit with a cord and plug should not exhibit surface

leakage current greater than 3.5 milliampere (mA) as

determined by testing completed in accordance with

“Leakage Current Test for Plug-and-Cord Equipment”

in SEMI S9.

EXCEPTION: Equipment with leakage current

exceeding 3.5 mA is acceptable if documentation is

provided to substantiate that the equipment is fully

compliant with an applicable product safety standard

that explicitly permits a higher leakage current.

13.6.2 Equipment grounding circuits should have a

measured resistance of one-tenth (0.1) ohm or less as

determined by testing in accordance with SEMI S9.

13.7 Equipment in which flammable liquids or gases

are used should be assessed to determine if additional

precautions (e.g., purging) in the electrical design are

necessary.

NOTE 44: NFPA 497 and EN 1127-1 provide methods for

making this assessment.

14 Fire Protection

14.1 Overview — This section applies to fire hazards

that are internal to the equipment.

14.1.1 This section provides minimum safety

considerations for fire protection designs and controls

on the equipment.

14.1.2 This section also provides minimum

considerations for fire detection and suppression

systems when provided with the equipment.

NOTE 45: Detailed guidance on fire risk assessment and

mitigation for semiconductor manufacturing equipment is

provided in SEMI S14.

14.2 Risk Assessment

14.2.1 A documented risk assessment should be

performed or accepted by a party qualified to determine

and evaluate fire hazards and the potential need for

controls. The risk assessment should consider normal

operations and reasonably foreseeable single-point

failures within the equipment. It should not consider

exposure to fire or external ignition sources not within

the specified use environment.

NOTE 46: This risk assessment can be combined with the

overall hazard analysis performed for this guideline, provided

the risk assessor has the required professional expertise to

perform risk assessments for fire hazards. SEMI S7 describes

qualifications for such an assessor.

14.2.2 If an accurate risk assessment depends on the

user’s adherence to specified procedures or conditions

of use, the supplier should describe such procedures or

conditions and state their importance.

14.2.3 SEMI S14 should be used to assess and report

risks to property and the environment.

14.3 Reporting

14.3.1 A summary report should be provided to the

user. The summary should include the following

characterizations, per SEMI S10, for each residual fire

hazard identified:

 the assigned Severity;

 the assigned Likelihood; and

 the resulting Risk Category.

14.3.2 Optional fire risk reduction features should be

described in the pre-purchase information provided to

the user.

14.3.3 The scope and effectiveness of the means of fire

risk reduction should also be identified and reported,

including the expected risk reduction (as described in

Section 14.3.1).

14.3.4 If, due to fire hazards within the equipment,

thermal or non-thermal (e.g., smoke) damage is

possible outside of the equipment, then this possibility

should be reported to the user. This report should

include a qualitative description of the foreseen

scenario.

14.4 Fire Risk Reduction

14.4.1 Materials of Construction — Equipment should

be constructed of noncombustible materials wherever

reasonable. If process chemicals do not permit the use

of noncombustible construction, then the equipment

should be constructed of materials, suitable for the uses

and compatible with the process chemicals used, that

contribute least to the fire risk.

SEMI S2-0703a

NOTE 47: Some regional codes (e.g., Uniform Fire Code)

may require construction with noncombustible materials.

14.4.1.1 The flowchart in Appendix 6 may be used for

the selection of materials of construction for equipment.

14.4.1.2 Any portion of equipment that falls within the

scope of SEMI F14 (Guide for the Design of Gas

Source Equipment Enclosures) should be designed in

accordance with that guide.

14.4.2 Elimination of Process Chemical Hazards —

The option of substituting non-flammable process

chemicals for flammable process chemicals should be

considered.

14.4.3 Engineering Controls

14.4.3.1 Fire risks resulting from process chemicals

may be reduced using engineering controls (e.g.,

preventing improper chemical mixing, preventing

temperatures from reaching the flash point).

14.4.3.2 Fire risks resulting from materials of

construction may be reduced using engineering controls

(e.g., non-combustible barriers that separate

combustible materials of construction from ignition

sources, installing a fire suppression system that

extinguishes ignited materials).

14.4.3.3 Equipment power and chemical sources that

present unacceptable fire risks should be interlocked

with the fire detection and suppression systems to

prevent start-up of the equipment or delivery of

chemicals when the fire detection or suppression is

inactive.

NOTE 48: Some jurisdictions require interlocking.

NOTE 49: Refer to Section 6.5 for criteria for acceptability.

14.4.3.4 Shutdown or failure of a fire detection or

suppression system need not interrupt the processing of

product within the equipment by immediately shutting

down the equipment, but should prevent additional

processing until the fire detection or suppression is

restored. Software or hardware may be used for this

function.

14.4.3.5 Controlling smoke by exhausting it (using the

supplier-specified equipment exhaust) from the

cleanroom may be used to reduce fire risks from the

generation of products of combustion. When used, this

reduction method should be combined with detection or

suppression when flames can be propagated.

NOTE 50: Controlling smoke may be sufficient when smoke

is the only consequence (e.g., smoldering components that

generate smoke).

NOTE 51: For controlling smoke to be effective, the smoke

must be removed not only from the equipment, but also from

the cleanroom. This is typically accomplished by using ducted

exhaust.

NOTE 52: The use of exhaust to remove smoke may be

subject to regulations, such as building and fire codes.

NOTE 53: The use of exhaust to remove smoke may create

hazards within the exhaust system. Therefore, a description of

the expected discharge (i.e., anticipated air flow rate,

temperature, and rate of smoke generation) into the exhaust

system may be important information for installation of

equipment.

14.4.4 Fire Detection — The following criteria apply

to any fire detection system determined to be

appropriate for fire protection by the fire risk

assessment:

NOTE 54: Heat detectors, smoke sensing devices, and other

devices used solely for monitoring equipment status may not

need to meet these requirements. Some local jurisdictions,

however, may require that all smoke detectors be connected to

building systems and be compliant with all applicable fire

alarm codes.

14.4.4.1 The fire detection system, which includes

detectors, alarms and their associated controls, should

be certified by an accredited testing laboratory and

suitable for the application and for the environment in

which it is to be used.

NOTE 55: Such certifications typically require that the

components of fire detection systems are readily identifiable

and distinguishable from other components in the equipment.

14.4.4.2 The fire detection, alarm and control system

should be installed in accordance with the requirements

of the certification in Section 14.4.4.1, and in

accordance with requirements of the appropriate

international or national codes or standards (e.g., NFPA

72).

14.4.4.3 The fire detection system should be capable of

interfacing with the facility’s alarm system. It may be

preferable for the equipment supplier to specify the

location and performance of detectors, but not provide

them, so that the user may better integrate the detection

in the equipment with that in the facility. This

alternative should be negotiated explicitly with the user.

14.4.4.4 The fire detection system should activate

alarms audibly and visually at the equipment.

14.4.4.5 Manual activation capability for the fire

detection system should be considered, for the purpose

of providing notification to a constantly attended

location.

14.4.4.6 Activation of trouble or supervisory

conditions should result in all of the following:

 notification of the operator;