ARTICLE 70 8 - CRITICAL OPERATIONS POWER SYSTEMS (COPS )
nergy storage shall also be marked with the maximum oper
a ' g voltage, including any equ alization voltage, and the
of the grounded circuit conducto r.
1
h
705.E Hybrid Systems. Hybrid systems shal l be pfrmitt ed to ' be i nterconnec te d wi th u tility-interac tive inv^tters.
fs
705.95 Alnpacity of Neutral Conductor. If a sing leph ase, 2-whip inverter ou tput is co nnec ted to the neutral an d
o ne ungrou ri^ed conductor (only) of a 3-wire sy stem or of a
3-ph ase, 4 -wi ne , wye-co nnected sys tem , th e max i mum load
conne cted b et^een the neutral an d any o ne ungrounded
conductor plu s the inverter outpu t rating shall not excee d
the ampac i ty of the neu tral co nductor. -
708.2
1. General
708.1 Scope. The provisio n s of this arti cl e apply to the
i nstallati on, operation , monitoring, control , and mainten ance of the p ort i ons of the premises wi ring system in ten de d t o supp l y, distri b ute, a n d control electricity to designated criti cal op erations areas (D C O A) i n the event of
di sruptio n to elements of the n ormal sys tem.
Critical operati on s p ower systems are th ose sys tems so
classed by mu ni cip al , state, fe deral , or other codes by any
governmenta l agency havi ng ju ri sd ic tion or b y facility en g i neering doc umentati on estab lishing the n ecess ity for such
a sys tem. These sys tem s inclu de but are n ot limi ted to
power sys tems, HVAC , fire al arm, security, communicatio n s, an d sign aling fo r desig n ate d c ritical operations areas.
705.100 Unbalanced Interconnections.
(A) Single Phase. S in gl e-phase i nverters for hybrid systems and ac modules i n interac tive hybrid system s shall n ot
b e connected to 3-ph ase power s ystems unless the i nterco nnected sys tem is des i g ned s o that s ignificant unb al anced
voltages canno t res ult.
(B) Three Phase. Three-ph as e inverters and 3-ph ase ac
modules in interactive systems shall have all ph ases automatically de-energized up on lo ss of, or unbal anced, voltage in one
or more phases unless the interconnected system is designed
so that sig nificant unbalanced voltages will not resu lt.
III. Generators
FPN No. 1: Critical operations power systems are generally installed in vital infrastructure facilities that, if destroyed or incapacitated, would disrupt national security,
the economy, public health or safety; and where enhanced
electrical infrastructure for continuity of operation has been
deemed necessary by governmental authority. °
FPN No. 2: For further information on disaster and emergency management see NFPA 1600-2007, Standard on
Disnstei/Eniergency Management and Business Continuity
Programs.
FPN No. 3: For further information regarding performance
of emergency and standby power systems, see NFPA 1102005, Standard for Emergency and Standby Power Systems.
FPN No. 4: For further information regarding performance
and maintenance of emergency systems in health care facilities, see NFPA 99-2005, Standard for Health Care
Facilities.
705.130 Overcurrent Protection. C onductors shal l b e
protected in ac cordance with Article 240. equip ment and
conductors c onnec ted to more than o n e el ec trical source
s h all h ave o vercurrent devices located so as to p rov ide protec ti on from all sources. Gen erators shall b e protected in
accord ance with 445 .12.
FPN No. 5: For specification of locations where emergency lighting is considered essential to life safety, see
NFPA 101 °-2006, Life Safety Code° .
705.143 Synchronous Generators. S ynchrono u s generators in a parallel system s h al l b e provided with the ne cessary equipment to estab li s h and m aint ain a sy nchrono u s
n di ti o n .
FPN No. 7: Threats to facilities that may require transfer of
operation to the critical systems include both naturally occurring hazards and human-caused events. See also A.5.3.2
of NFPA 1600-2007.
FPN No. 6: For further information on regarding physical
security, see NFPA 730-2006, Guide for Premises Security.
FPN No. 8: See Annex G for information on Supervisory
Control and Data Acquisition.
708.2 Definitions.
ARTICL E 708
Critical Operations Power Systems
(COPS)
FPN: Rules that are followed by a reference in brackets
contain text that has been extracted from NFPA 1600-2007,
Standard on Disaster/Emergency Management and Bitsiness Continuity Programs. Only editorial changes were
made to the extracted text to make it consistent with this
Code.
2008 Edition
NATIONAL ELECTRICAL CODE
Commissioning. The acceptance testing, integrated system
testing, operational tune-up, and start-up testing is the process by which baseline test results verify the proper operation and sequence of operation of electrical equipment, in
addition to developing baseline criteria by which future
trend analysis can identify equipment deterioration.
Critical Operations Power Sys tems (COPS). P ower systems for fac i lities or parts of faci l ities th at require continuous operation for the reasons of public safety, emergency
management, national sec urity, o r bu s i ness continuity.
70-609
708.3
ARTICLE 708 - CRITICAL OPERATIONS POWER SYSTEMS (COPS)
41
D esi gnat d Critical Operation s Areas (DCOA) . Areas
e
within a facility or site designated as requiring critical op erations p ower.
Sup ervis ory Control and Data Acquisition (SCADA) .
An electronic sys tem that provides moni toring and control s
for the operation of the critical op erations p ower system.
This can include the fire alarm s ystem, security system ,
control of the HVAC , the start/stop/monitoring of the
power suppli es and el ectric al distribution system, annun ciation and communication equipment to emergency p ersonnel , facility occup ants, and remote op erators.
708.3 Application of Other Articles. Except as modified
by this article, all applicable articles of this Code shall apply.
708 .4 Risk Assessment. Ri sk assess ment for critical op erations power systems sh all b e documented and shall b e
conducted in acc ordance with 70 8.4(A) through (C).
FPN: Chapter 5 of NFPA 1600-2007, Standard on Disnstei/
Emergency Management and Business Continuity Programs,
provides additional guidance concerning risk assessment and
hazard analysis.
(A) Conducting Risk Assessment. In critical operation s
power systems, ri sk assess ment shall b e p erformed to identify h azards, the likelihoo d of their o ccurrence, and the
vulnerabili ty of the electrical system to those hazards.
(B) Identification of Hazards. Hazard s to b e con sidered at
a minimum shall include, but shall not be limited to, the
following:
( 1 ) Naturally occurring hazards (geological , meteorological , and biological )
(2) Human cmi-d
[ 1600: 5.3.2]
events
(accidental
and intentional)
708.6. Tes ting and Maintenance.
(A) Conduct or Witness Test. The authority having jurisdiction shall condu ct or witness a test of the complete system upon installation and periodi cally afterw ard .
(B) Tested Periodically. S ystems shall b e tested p erio dically on a schedule acceptable to the authority having jurisdiction to ensure the s ys tems are maintained in proper
op erating c ondition .
(C) Maintenance. The authority havi ng juri s di ction sh all
require a documented preventive maintenance program for
critical operations p o wer systems.
FPN: For testing and maintenance procedures, see NFPA
70B-2006, Recommended Practice for Electrical Equipment Maintenance.
(D) Written Record. A written record shall b e kept of
such tests and maintenance.
(E) Testing Under Load. Means for testing all critical
power systems during maximum anticipated load conditions shall be provided.
FPN: For testing and maintenance procedures of emergency power supply systems (EPSSs) that are also applicable to COPS, see NFPA 110-2005, Standard for Enier•gency and Standby Power Systems.
708.8 Commi ssioning.
(A) Commissioning Plan. A commissioning plan shall be
develop ed and documented .
FPN: For further inform ation on developing a commiss i oning program see NFPA 70B -2006, Recom mended Practice
for Elec trical Equipment Maintenance.
<.l
(B) Component and System Tests. The inst all ation of the
equipment shall undergo component and system tests to ensure that, when energized , the system will function properly.
(C) Developing Mitigation Strategy. Based on the results of
the risk assess ment, a strategy shall be developed and implemented to mitigate the hazards that have not been sufficiently
mitigated by the prescriptive requirements of this Code.
(C) Baseline Test Results. A set of b aseline test results
shall be documente d for comparison with future perio dic
maintenan ce testing to identify equipment deterioration .
708 .5 Physical Security. Phys i cal security shall be provided for cri tical op erati ons power systems in accordance
with 708.5(A) and (B).
(D) Functional Performance Tests. A functional p erformance tes t program sh all be established , documented , and
executed up on complete in stallation of the critical sys tem
in order to establi sh a baseline reference for future performan ce requirements.
(A) Risk Assessment. B ased on the results of the risk assess ment, a strategy for providin g physical security for
cri tical operations p ower systems sh all be devel op e d , docu mented , and i mpl emented .
FPN: S ee Annex F for more information on developing
and implementing a functional performance test program.
II. Circuit Wiring and Equipment
(B) Restricted Access. Electrical circui ts and equipment
for critical operations p ower systems shall be accessib le to
qu alified p ersonnel only.
70-610
Ii
708.10 Feeder and Branch Circuit Wiring.
(A) Identification.
NATIONAL ELECTRICAL CODE
2008 Edition
Gip
.^r
708.1 4
ARTICLE 708 - CRITICAL OPERATIONS POWER SYSTEMS (COPS)
(1) Boxes and Enclosures. All boxes and enclosures (in cluding transfer switches, generators, and p ower p anels) for
critical op erations power system circuits shall be p erma•nently marked so they will b e readily identified as a component of the sy stem .
(2) Receptacle Identification. The cover plates for the
electrical receptacles or the electrical receptacles themselves suppli ed from the COPS shall have a distinctive
color or marking so as to b e re adily identifi able.
00
(4) B e a cable listed to maintain circuit integrity for not
less than 1 hour when installed in accordance with the
lis ting requirement
(3) Floodplain Protection. Where COPS feeders are in stalled b elow the level of the 1 00-year fl oo dplain , the circuit condu ctors shall be listed for u se in a w et loc ation and
be instal led in a wiring metho d th at is p ermitted for u se in
wet locations.
(D) COPS Branch Circuit Wiring.
(B) Wiring. Wiring of two or more COPS circuits suppl ied
from the same source shall b e p ermitted in the same race.way, cable, box, or cabinet. Wiring from a COPS source or
COPS source distribution overcurrent protection to critica l
lo ads shall b e kept entirely independent of all other wiring
and equipment .
(a) Outside the D COA. COPS branch circuits in stalled
outside th e DCOA shall comply with the physical and fire
protection requirement s of 70 8. 10 (C)(1) through (C)(3).
(b) With in the DCOA . Any of the wiring metho ds recognized in Ch apter 3 of this Code shall b e permitted within
the DCOA.
Exception: Where the COPS feeder- is installed in transfer
equipment enclosures.
708.11 Branch
Equipment.
(C) COPS Feeder Wiring Requirements. COPS feeders
shall comply with 708.10(C)(1) through (C)(3).
(A) Branch Circuit Dis tribution Equipment. COPS
branch circuit dis tribution equipment shall b e located
within the same DCOA as the branch circuits it supplies.
(1) Protection Against Physical Damage. The wiring of
the COPS system shall b e protected against physical dam-age. Wirin g methods shall b e p ermitted to b e install ed in
accordance with the following:
(1 ) Rigid metal conduit, intermedi ate metal conduit, or
Type MI cable.
(2) Where encased in not less than 50 mm (2 in .) of con-crete, any of the following wiring methods shall be
p ermitted :
a. S chedule 40 or S chedule 80 rigid polyvinyl chloride
condui t (Typ e PVC)
b . Reinforce d thermosettin g resin conduit (Typ e
RTRC)
c . Electrical metallic tubing (Type EMT)
d . Flexible nonmetallic or jacketed met allic raceways
e. Jacketed metallic cable assemblies li sted for in stal.lation in concrete
(3) Where provisions mu st be made for flexibility at equip ment connection , one or more of the following shall
also b e p ermitted :
a. Flexible metal fittin gs
b . Flexible metal condu it with listed fittings
c. Liquidti ght flexible metal condui t with listed fitti ngs
Circuit
and
Feeder
Distribution
(B) Feeder Distribution Equipment. Equipment for
COPS feeder circuits (including transfer equipment, transformers, and panelb oards) shall comp ly with (1) and (2).
( 1) B e l ocated in sp aces with a 2 -hour fire resis tance rati ng
(2) B e locate d ab ove the 100 -year fl oodpl ain.
708.12 Feeders and Branch Circuits Supplied b y
COPS. Feeders and branch circ uits suppli e d by the COPS
sh all supply only e quipment specifie d as required for critic al op erations u se.
708.14 Wiring of HVAC, Fire Alarm, Security, Emergency Communications, and Signaling Systems. All conductors or cables sh all b e ins talled using any of the metal
wiring methods permitted by 708.1 0 (C)( 1 ) and in addition
shall comply with 708.14(1) through 708.14(8) as applicable.
(1) S ignal and communication wires shall u se shielded
twiste d p airs.
(2) Shields of sign al and communication wires shall b e
continuous.
(3) Fiber opti c cables shal l b e u sed for connections b etween two or more buildings on the property and under
single man agement.
(2) Fire Protection for Feeders. Feeders shall meet one of
the following conditi ons:
( 1 ) B e a l isted electri cal circuit protective system with a
minimum 1 -hour fire rating
(4) Listed secondary protectors sh all be provided at the
terminals of the communication circuits.
(2) B e protected by a fire-rate d assembly listed to achi eve
a minimum fire rating of 1 hour
(3) B e emb edded in not less th an 50 mm (2 in .) of concrete
(6) Communications, fire alarm , and sign aling circuits
shall u se rel ays with contac t ratings that exceed circuit
vo ltage and current ratings in the controlled circu it.
2008 Edition
NATIONAL ELECTRICAL CODE
( 5 ) Conductors for all control circuits rated ab ove 50V
shall be ins talled with wire rated not less than 600V.
70-611
708.20
ARTICLE 708 - CRITICAL OPERATIONS POWER SYSTEMS (COPS)
(7) Riser communication cables shal l be 2-hour fireres istive cable or a lis ted 2-hour electri cal circuit protec tive sys tem .
( 8) Control , monitoring, and power wiring to HVAC sy stems shall be 2 -hour fire-resistive cable or a lis ted
2 -hour electrical circuit protective system .
III. Power Sources and Connection
708.20 Sources of Power.
(A) General Requirements. Current supply s h all b e such
th at, in th e event of failure of th e normal suppl y to th e
DCOA , critical operations p ower shall b e available within
the time required for the application . The supply system for
critic al operation s power, in additi on to the normal servic es
to the building and meeting the general requirements of thi s
section , shall b e one or more of the types of systems described in 708.20(D) through (H).
FPN: Assignment of degree of reliability of the recognized
critical operations power system depends on the careful
evaluation in accordance with the risk assessment.
(B) Fire Protection. Where l ocat ed within a building,
equipment for sources of power as des cribed in 708 . 20 (D)
through (H) shall b e i nstalled either in sp aces fully protected by approve d automatic fire s uppre ssion s ystems
(sprinklers, carbon dioxi de systems, and so forth) or in
spaces with a 1 -hour fire rating.
^
(C) Grounding. All sources of p ower shall be grounded as
a separately derived source in accordance with 250 . 30 .
(2) Power for fuel transfer pumps . Where power is
nee ded for the op eration of the fuel transfer pumps to deliver fuel to a generator set day tank, this pump shall be
connected to the COPS .
(3) Dual Supplies. Prim e movers shall not b e s olely dependent on a publi c utility gas system for their fuel supply
or municipal water supply for their co oling systems. Means
sh all be provided for automatically transferring from one
fuel supply to another where dual fuel supplies are used .
(4) Battery Power and Dampers . Where a storage battery
i s used for c ontrol or s ignal p ower or as the mean s of
starting the prime mover, it shall be suitable for the purp ose
and sh all b e equipp ed with an automatic ch arging mean s
independent of the generator set . Where the battery charger
is required for the op eration of the generator set, it s hall be
connected to the COPS . Where p ower is required for the
operati on of damp ers used to ventilate the generator set, the
damp ers shall b e connected to the COPS .
(5) Outdoor Generator Sets . Where an outdoor housed
generator set is equipp ed with a readily access ible disconnecting means located within sight of the building or structure suppli ed , an additi on al dis connecting mean s shall not
be required where ungrounded conductors serve or p ass
through the buildin g or s tructure.
(6) Mean for Connecting Portabl e or Vehicle-Mounted
Generator. Wh ere th e COPS is s uppli ed by a singl e gena means to connect a portable or vehicle-mounted
generator shall b e provided .
Exception : Whe re the equ ipment conta ining the main
bonding jumpe r or system bonding jumper for the no rma l
so u rce and th e feeder wiring to th e transfer equipment are
installed in accordan ce with 7081 0(C) an d 708. 11 (B).
(7) On-Site Fuel Supply. Where internal combustion engines are use d as the prime mover, an on-site fue l supply
shall be provided . The on-site fuel supply shall be secured
and protected in accorda n ce with the risk assess ment.
(D) Surge Protection Devices. Surge protection devic es
shall b e provide d at all facility distribution voltage l evel s.
(G) Uninterruptible Power Supplies. Unint erruptible
p ower suppli es u sed as the sole source of p ower for COPS
shall comply with the applic able provi sion s of 708 .20 (E)
and (F).
(E) Storage Battery. An automatic battery ch arging
means sh all b e provi ded . B atteries sh all b e c ompatible with
the charger for that p articular in stallation . For a seale d battery, the container shall not be re quired to be transp arent .
However, for the lead acid b attery that requires water addition s, transparent or translucent j ars shall b e furnished .
Automotive-typ e b atteries shall not be used .
(F) Generator Set.
(1) Prime Mover-Driven. G enerator sets driven by a
prime mover shall b e provided with means for autom atically starting the prime mover on failure of the normal
service. A time- del ay feature permitting a minimum 15 minute setting shall be provided to avoid retransfer in case
of short-time reestablishment of the normal source.
70-612
(H) Fuel Cell System. Installation of a fuel cell system
sh all meet th e requirement s of Part s II through VIII of
Article 692.
708.22 Capacity of Power Sources.
(A) Capacity and Rating. A COPS shall have capacity
and rati ng for all loads to b e op erated sim u ltaneou sly for
contin uous operation wi th variable load ,for an unlimited
number of hours, except for req u ired maintenance of the
p ower s ource. A p ortable, temporary, or redund ant alternate
po wer source shall b e available for u se whenever the COPS
power source, is ou t of service-for maintenance or rep air.
NATIONAL ELECTRICAL CODE
2008 Ed i tion
ARTICLE 708 - CRITICAL OPERATIONS POWER SYSTEMS (COPS)
31
(B) Selective Load Pickup , Load Shedding, and Peak
Load Sharing. The altern ate power s ource shall b e p ermitted to supply COPS emergency, legally required standby
and option al lo ads where the source has adequ ate cap acity
or where automatic selective lo ad pickup and load shedding
i s provided as needed to ensure adequate power to (1 ) the
COPS and emergenc y circuits, (2) the legally required
standby circuits, and ( 3 ) the optional standby circuits, in
that order of priority. The alternate power source shall be
p ermitted to be u sed for p eak lo ad shaving, provided thes e
conditi ons are met .
Peak lo ad-shaving operation sh all be p ermitted for satisfying the test requirement of 70 8. 6 (B) , provided all other
conditions of 708.6 are met.
(C) Duration of COPS Operation. Th e alte rn ate dower
,sou rce _shall be cap able of operating the C OPS for a minimum of 72 h ours at ful l load of D COA with asteady-state
voltage within ±1 0 p ercent of nominal utilization voltage.
(D) Ventilation. Adequate ventil ation shall b e provided for
the alternate p ower source for continued operation under
maximum anticip ated ambient temperatures.
FPN: NFPA 110-2005, Standardfor Emergency and Standby Power Systems, and NFPA 111-2005, Standard for
Stored Energy Emergency and Standby Power Systems, include additional information on ventilation air for combustion and cooling.
708.54
708.30 Branch Circuits Supplied by COPS. Branch circuits supplied by the COPS shall only supply equipment
specified as required for critical operations use.
IV. Overcurrent Protection
708.50 Accessibility. The feeder- and branch-circuit overcurrent devices shall b e accessible to authorized p ersons
only.
708 . 52 Ground-Fault Protection of Equipment.
(A) Applicability. The requirements of 708.52 shall apply
to critical operations (includin g multiple o ccup ancy buildings) with critical op eration areas.
(B) Feeders. Where ground-fault protection i s provided
for operation of the service disconnecting mean s or feeder
dis connecting means as specified by 230 . 95 or 215 . 10 , an
addition al step of ground-fault protecti on shall b e provided
in all next level feeder disconnecting means downstream
toward the load . Such protection shall con sist of overcurrent devices and current tran sformers or other equivalent
protective equipment that c au ses the feeder disconnecting
mean s to op en .
The additional l evels of ground-fault protection shall
not b e installed on electric al s y stems that are not solidly
grounded Wye systems with greater than 150 volts to
ground but no t excee ding 600 volts phase-to-phase.
708.24 Transfer Equipment.
(A) General. Transfer equipment , including automatic
transfer switches, shall be automatic and identified for
emergency u se. Transfer equipment shall b e designed and
installed to prevent the in advertent interc onnection of normal and critical operations sources of supply in any operation of the tran sfer equipment . Transfer equipment and
electric p o wer pro duction systems installed to permit op eration in p arallel with the normal source shall meet the
requirements of Article 705 .
(B) Bypass Isolation Switches. Mean s shall b e p ermitted
to byp ass and is olate the transfer equipment . Where bypass
isolation switches are u se d , inadvertent parallel operation
shall b e avoided .
(C) Automatic Transfer Switches. Where u sed with
sources that are not inherently synchronized , automatic
transfer switches shall comply with ( C)(1) and (C)(2).
( 1 ) Automatic transfer switches sh all b e listed for emergency u se.
(2) Automatic tran s fer swi tches sh all b e electrically operated and mechani cally held .
(D) Use. Transfer equipment shall supply only COPS
load s.
(C) Testing. When equipment ground-fault protection is
fi rst installed , each level shall be tested to ensure that
ground-fault protection i s operational .
FPN: Testing is intended to verify the ground-fault function is operational. The performance test is not intended to
verify selectivity in 708.52(D), as this is often coordinated
similarly to circuit breakers by reviewing tie and current
curves and properly setting the equipment. (Selectivity of
fuses and circuit breakers is not performance tested for
overload and short circuit.)
(D) Selectivity. Ground-fault protection for op eration of
the service and feeder disconnecting means shal l be fully
selective such that the feeder device, but not the service
device, shall op en on ground faults on the load side of the
feeder device. A six-cyc le minimum separation between the
service and feeder ground-fault tripping b and s shall b e provided . Operating time of the di sconnecting devices shall b e
considered in selecting the time spread b etween these two
b ands to achieve 100 p ercent selectivity.
FPN: See 230.95, FPN No. 4, for transfer of alternate
source where grou nd-fault protec tion is applied.
708 . 54 Coordination. Critica l operations power system(s)
overcun•en t devices sh all be selectively coordin ated with all
supply si de overcurrent protective devices.
IV
V
2008 Edition
NATIONAL ELECTRICAL CODE
70-613
708.64
ARTICL E 725 - CLASS 1 , CLASS 2 , AND CLASS 3 REMOTE- CONTROL, SIGNALING, AND POWER- LIMITED CIRCUITS
V. System Performance and Analysis
708.64 Emergency Operations Plan. A fac i lity with a
COPS sh all h ave doc umented an emergency op eration s
p l an . Th e plan shall co n si der emergency operat i on s and
resp on se, recovery, and co ntinuity of operati on s.
FPN: NFPA 1600-2007, Standard on DisasterlEtnergency
Management and Business Continuity Programs, Section
5.7, provides guidance for the development and implementation of emergency plans.
ARTICLE 720
Circuit s and E quipment Operating
at Less Than 50 Volts
/..
720.1 Sc pe. Thi s arti cle covers in s t all ation s operatin g at
volt s, direct current or altern atin g cu rrent.
l ess th a n
720.2 Other 'Articles. Direc t current or a l tein atin g-c uffent
i nstal l at i o n s operat ing at l ess t h an 50 vo lts , as covered in
4 1 1 .1 thro u gh 44 1 .7; P ar t VI of Artic l e 5 17; Part II o f
Article 55 1 ; Parts'V I and III and 552.60(B) of Article 552;
650.1 thr ough 650 $ ; 669.1 through 669.9; Parts I and VIII
of Art ic l e 690; Parts '6d III of Artic le 725; or Parts I and III
of Article 7 60 sh all not b e required to comply w ith thi s article.
720.3 Hazardous (Classified) Locations. In stal l ati on s
within th e scope of this atticle an d i n s t a lled in h azardous
(c l ass i fied ) locat i ons shall also co mply w i th the appropriate
provi s ion s for h azardou s (c l s ifie d) l ocati on s i n other ap pl icabl e articles of this Co de.
20.11 Mechanical Execution of Work. Circuits operat-7
i
at less than 50 v ol ts s h al l b e in s tal led in a neat a
w kmanlik e manner. C ables shall be supp orted by
e
b u i Ving s tru c ture in s u ch a mann er th at the cable Will 4of
b e dkmaged by norm al build i n g u se.
F^
q
ARTICLE 725
ass 1 , Class 2, and Class 3
emote - Control , Signalin g,
aid Power-Limited Circuits
1
l[. General
725.1 Scope. This article covers remote -control, signaling,
and power-limited circuits that are not an integral part of a
device or appliance. ..
FPN: The circuits described herein are characterized by
usage and electrical power limitations that differentiate
them from electric light and power circuits; therefore, alternative requirements to those of Chapters 1 through 4 are
given with regard to minimum wife sizes, derating factors,
overcurrent protection, insulation requirements, and wiring
methods and materials.
725.2 Definitions.
Abandoned Class 2, Cla ss 3 , and PLTC Cabl e . Installed
C l ass 2, Cl ass 3, an d PLTC cable th at i s no t terminated at
e quipment a nd n o t identifi e d for future u s e with a t ag.
Circuit Integrity (CI) Cable. Cab le(s) used for re motecon t ro l , sig n al ing, or p ower- limite d system s th at s uppl y
cri t i cal ci rcuits to en s ure surv i vabil i ty for co n ti nued c ircu i t
operat i o n for a specifi e d ti me u nder fire co ndit io n s.
720.4 Conductors. Co nd uctors shall no t b e small er th a n
12 AW G copp er or equ i val ent. Con ductors for appli ance
bran ch c i rcuits s u pp lying more th an o ne appliance or appli ance recep t acl e s h a ll no t b e s maller than 1 0 AWG copper or
e q uivalent.
Class 1 Circuit. The p orti on of the wi ri ng sys tem between
the l oad si d e of the overc u irent device or power-li mi te d
supp ly and the c on nec ted e qu ipme nt .
720.5 Lampholders. St a nd ard l amp holders th at h ave a rati ng of n o t l ess th an 660 watts s h a ll b e u se d,
Class 2 Circuit. The p ortio n of the wiri ng sys tem be tween
th e l oad side of a C l ass 2 p ower source an d th e connected
eq uip ment. D u e to its p ower l imitat i o n s, a C l as s 2 c irc uit
co n s i ders safe ty fro m a fire initi at i o n s t andpoint an d pro vides ac c ep t ab le pro tecti on from electric shoc k .
720.6 Receptacle Rating. Receptac l es sh a ll ha ve a rating
of not less than 15 amperes.
720.7 Receptacles Required. Recep t ac l es of not le ss th an
20-ampere rating shall be provided in kitchens, laundries, and
other locations where portable appliances are likely to b&,used.
720.9 Batteries. Installations of storage batteries shall ckply with 480.1 through 480.4 and 480.8 through 480.10.
70-614
FPN: S ee 725 .2 1 for vo lt age and p ower limit ations of
C l ass I c i rc uit s.
Class 3 Circuit. The p ort io n of the w iring sys tem b etween
the load s ide of a Cl ass 3 power source and the connected
equ ipment. Due to its power li mitatio n s, a Class 3 circu i t conside s safety from a fi re initiation standpoint . Since higher
l ey'el s of vol t age and current t h an for Class 2 are permitted ,
ad it ional sa feguard s are specified to provide protectio n frornr
electri c sh ock hazard th at could be encountered .
NATIONAL ELECTRICA L CODE
2008 Edition