Table Of ContentBOSTON PUBLIC LIBRARY ^T2
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THE COMMONWEALTH OF MASSACHUSETTS
DEPARTMENT OF PUBLIC SAFETY
BOARD OF FIRE PREVENTION REGULATIONS
MASSACHUSETTS ELECTRICAL CODE
RULES AND REGULATIONS
GOVERNING THE
INSTALLATION, REPAIR AND MAINTENANCE
OF ELECTRICAL WIRING AND ELECTRICAL
FIXTURES USED FOR LIGHT, HEAT AND POWER
IN BUILDINGS AND STRUCTURES SUBJECT
TO THE PROVISIONS OF SECTIONS 3 TO 60,
CHAPTER 143, G. L, TER. ED., AS AMENDED
FORM
FPR-11
BOSTON
PUBLIC
LIBRARY
^
OFFICE CF THE SECRETARY
STATE HOUSE, BOSTON, MASS.
Rules and Regulations filed in this Office under the provisions of
CHAPTER 30A as amended.
DEPARTMENT OF PUBLIC SAFETY
Filed by BOARD OF FIRE PREVENTION REGULATIONS - FPR-II
MASSACHUSETTS ELECTRICAL CODE
Date Filed NOVEMBER 9. 1972
Date Pnhlishpd DKCRMBKR 20, 1Q72
Chapter 233, sec. 75
Printed copies of rules and regulations purporting to be issued by
authority of any department, commission, board or Officer of the
Commonwealth orany city or town havingauthority toadopt them,
or printed copies of any ordinances or town by-laws, shall be ad-
mitted without certification or attestations, but if this genuineness
is questioned, the court may require such certifications or attesta-
tions thereof as it deems necessary.
Attestedasatruecopy
JOHN DAVOREN
F. X.
SECRETARY OF THE COMMONWEALTH
—
Acts, 1950. Chap. 617.
Chap.617 ^N ^^^ "^^ PROVIDE FOR RULES AND REGULATIONS RELATIVE
TO THE INSTALLATION, REPAIR AND MAINTENANCE OF
ELECTRICAL WIRING AND ELECTRICAL FIXTURES USED FOR
LIGHT, HEAT AND POWER PURPOSES.
Be it enacted, etc., asfollows:
G. L. (Ter. Section 1. Chapter 143 of the General Laws is hereby
Ende.w),§134L3,, amend—ed by inserting after section 3K the following sec-
added. tion Section 3L. The board of fire prevention regulations
mBoaakredrtuoles shall: make and promulgate, and from time to time may
atinodnsr,eegtucl.a,- alter, amend and repeal, rules and regulations relative to the
relative to installation, repair and maintenance of electrical wiring and
installation,
repair, etc., of electrical fixtures used for light, heat and power purposes in
electrical buildings and structures subject to the provisions of sections
wiring, etc.
three to sixty, inclusive. Such regulations shall be in ac-
cordance with generally accepted standards of engineering
practice, and shall be designed to provide reasonable uni-
form requirements of safety in relation to life, fire and ex-
plosion.
Upon the making of such rules and regulations and prior
to their promulgation, the board shall hold a public hearing
thereon, notice of which shall be given by advertising in at
least onenewspaper in each ofthe cities of Boston, Worcester,
Springfield, Fall River, Lowell and L3Tin, at least ten days
before said hearing. If, subsequent to their being deposited
with the state secretary, as provided herein, the board on its
own initiative contemplates changes in said rules and regu-
lations, or if a petition is filed by any other person for changes
therein, like notice and a hearing shall be given and held
before the adoption thereof.
Rules, etc., Such rules and regulations, and any alterations, amend-
to be deposited
with state ments or repeals thereof shall be deposited with the state
secretary. secretary, and the same shall become effective when so
deposited.
aByn-dloarwdsinances Section 2. Upon the filing with the state secretary of the
to be annulled, rules and regulations referred to in section three L of chapter
etc. one hundred and forty-three of the General Laws, inserted by
section one of this act, all by-laws and ordinances of cities
and towns relating to the installation, repair and mainte-
nance of electrical wiring and electrical fixtures used for light,
heat and power purposes in buildings and structures subject
to the provisions of sections three to sixty, inclusive, of said
chapter one hundred and forty-three shall be annulled.
Approved July 11, 1950.
———
72"i
TABLE OF CONTENTS
Article Page Article Page
90 Introduction 1 358 Cellular Concrete Floor
Raceways 157
362 Wireways 158
Chapter 1. General 363 Flat Cable Assemblies 159
364 Busways 161
100 Definitions 4
365 Cablebus 163
110 General 13
370 Outlet, Switch and Junction
Boxes, and Fittings 164
Chapter 2. Wiring Design and 373 Cabinets and Cutout Boxes 171
Protection 374 Auxiliary Gutters 174
380 Switches 176
200 Use and Identification of 384 Switchboards and
Grounded Conductors 18 Panelboards 179
....
210 Branch Circuits 21 390 Prefabricated Buildings 183
215 Feeders 29
220 Branch-Circuit and Chapter 4. Equipment for
Feeder Calculations 30 General Use
230 Services 42 400 Flexible Cords and Cables 184
240 Overcurrent Protection 58 402 Fixture Wires 194
250 Grounding 66 410 Lighting Fixtures, Lamp-
280 Lightning Arresters 89 holders, Lami>s, Recep-
tacles and Rosettes 198
Chapter 3. Wiring Methods and 442224 AFpipxleidanEcleesctric Space Heat- 213
Materials ing Equipment 219
—
300 Wiring Methods General 426 Fixed Outdoor Electric
Requirements 91 De-Icing and Snow-
305 Temporary Wiring 97 Melting Equipment 227
310 Conductors for General 430 Motors, Motor Circuits and
Wiring 98 Controllers 229
318 Continuous Rigid Cable 440 Air Conditioning and Re-
Supports 121 frigerating Equipment .... 263
320 Open Wiring on Insulators 123 445 Generators 272
324 Concealed Knob-and- 450 Transformers and Trans-
Tube Work 126 former Vaults 273
330 Mineral Insulated-Metal 460 Capacitors 280
Sheathed Cable 128 470 Resistors and Reactors 282
331 Aluminum Sheathed Cable 129 480 Storage Batteries ,.... 283
334 Metal-Clad Cable 130
336 Nonmetallic Sheathed Chapter 5. Special Occupancies
Cable 133 500 Hazardous Locations 286
337 Shielded Nonmetallic 501 Class I Installations
Sheathed Cable 135 Hazardous Locations 293
338 Service-Entrance Cable 136 502 Class II Installations-
339 Underground Feeder and Hazardous Locations 303
Branch Circuit Cable .... 137 503 Class III Installations
342 Nonmetallic Extensions 138 Hazardous Locations 312
344 Underplaster Extensions .... 140 510 Hazardous Locations
346 Rigid Metal Conduit 141 Specific 316
347 Rigid Nonmetallic Conduit 143 511 Commerical Garages,
348 Electrical Metallic Tubing .. 146 Repair and Storage 316
350 Flexible Metal Conduit 148 512 Residential Storage Garages 319
351 LiquidtightFlexible 513 Aircraft Hangars 319
Metal Conduit 149 514 Gasoline Dispensing and
352 Surface Raceways 150 Service Stations 323
353 Multioutlet Assembly 152 515 Bulk-Storage Plants 325
354 Underfloor Raceways 152 516 Finishing Processes 328
356 Cellular Metal Floor 517 Health Care Facilities 333
Raceways 154 520 Theaters and Assembly
357 Structural Raceways 155 Halls 351
72-ii MASSACHUSETTS ELECTRICAL CODE
Article Page Article Page
530 Motion-Picture Studios and 730 Outside Branch Circuits
Similar Locations 358 and Feeders 456
540 Motion-Picture Projectors .. 361 750 Stand-By Power Generation
550 Mobile Homes and Mobile Systems 460
Home Parks 363
551 Recreational Vehicles and
Recreational Vehicle Parks 375 Chapter 8. Communication Systems
555 Marinas and Boatyards 392
800 Communication Circuits .... 462
Chapter 6. Special Equipment 810 Radio and Television
Equipment 467
600 Electric Signs and Outline 820 Community Antenna Tele-
Lighting 394 vision and Radio Distribu-
610 Cranes and Hoists 400 tion Systems 473
620 Elevators, Dumbwaiters,
Escalators, and Moving
Walks 405 Chapter 9. Tables and Examples
630 Electric Welders 411
640 Sound-Recording and Tables - 477
Similar Equipment 415 Examples 489
645 Data Processing Systems .... 418
650 Organs 419
660 X-Ray Equipment 420 Index
665 Induction and Dielectric
Heating Equipment 425 Index 499
670 Metal Working Machine
Tools 430
680 Swimming and Wading
Pools 431
Chapter 7. Special Conditions
700 Emergency Systems 438
710 Over 600 Volts—General .... 442
720 Circuits and Equipment
Operating at Less Than
50 Volts 449
725 Remote-Control, Low-
Energy Power, Low-Voltage
Power and Signal
Circuits 450
72-ii
THE COMMONWEALTH OF MASSACHUSETTS
DEPARTMENT OF PUBLIC SAFETY
BOARD OF FIRE PREVENTION REGULATIONS
MASSACHUSETTS ELECTRICAL CODE
FORM FPR-n
In accordance with the provisions of G, L,, C. 143^
s, 3L, the Board of Fire Prevention Regulations herewith
makes thefollowing rules andregulations relativeto the in-
stallation, repair and maintenance of electrical wiring and
electrical fixtures used for light, heat and power purposes
inbuildings and structures subjecttothe provisions of G. L,,
C. 143, ss, 3 to 60, inclusive,
Riale 1, All installations, repairs and maintenance of
electricalwiring and electricalfixtures used for light, heat
and power purposes in buildings and structures subject to
theprovisions ofSections 3 to 60, Chapter 143, G. L„ Ter,
Ed,, as amended^ shall be reasonably safe to persons and
property.
Rule 2, Conformity ofinstallations, repairs and main-
tenance of electrical wiring and electrical fixtures used
for light, heat and power with applicable regulations set
forth in the code which is filed herewith with the Secretary
ofthe Commonwealth shallbe considered as complying with
these requiremjents.
Rule 3, Additions or modifications to an existing in-
stallation shall be made in accordance with this code with-
out bringing the remaining part of the installation to meet
the requirements of this code.
Rule 4, Where an actual hazard exists, the owner of
thepropertyshallbe notifiedin writing by the authority en-
forcing this code.
Rule 5« All references in this code to other standards
shall be considered as advisory and not mandatory.
Rule 6, The approving authority may be guided in his approval
of specific items of equipment and ma terials contemplated by the code, by
proof that such equipment and materials have been test-
ed and conform to suitable recognized industry standards.
MASSACHUSETTS ELECTRICAL CODE
72-iv
Note: With reference to the approval of specific
items of equipment and materials contemplated
by the code, it is pointed out that in order to
avoidthe necessityforrepetitionof examinations
by different examiners, frequently with inade-
quate facilities for such work, and to avoid the
confusionwhich wouldresultfrom conflictingre-
ports as tothe suitability of devices and mater-
ials examined for a given purpose, it is neces-
sary that suchexaminations shouldbe made un-
der standard conditions, and the record made
generally available through promulgation byoi*-
ganizations properly equipped and qualified for
experimental testing, inspections of the run of
goods at factories, and service-value determi-
nation through field inspections.
72-1
ARTICLE 90 -— INTRODUCTION
90-1. Purpose.
(a) The purpose of this Code is the practical safeguarding of per-
sons and of buildings and their contents from hazards arising from the
use of electricity for light, heat, power, radio, signalling and for other
purposes.
(b) This Code contains provisions considered necessary for safety.
Compliance therewith and proper maintenance will result in an installa-
tion essentially free from hazard, but not necessarily efficient, con-
venient, or adequate for good service or future expansion of electrical
use.
Hazards often occur because of overloading of wiring systems by meth-
ods or usage not in conformity with the Code. This occurs because initial
wiring did not provide for increases in use of electricity. For this reason it
is recommended that the initial installation be adequate and that reasonable
provisions for system changes be made as may be required for future in-
crease in the use of electricity.
(c) This Code is not intended as a design specification nor an instruc-
tion manual for untrained persons.
90-2. Scope.
(a) Covered. It covers the electric conductors and equipment in-
stalled within or on public and private buildings and other premises,
including yards, carnival and parking lots, and industrial substations;
also the conductors that connect the installations to a supply of elec-
tricity, and other outside conductors adjacent to the premises; also mo-
bile homes and recreational vehicles.
(b) Not covered. It does not cover:
(1) Installations in ships, watercraft, railway rolling stock, air-
craft or automotive vehicles (except mobile homes and recreational
vehicles).
(2) Installations underground in mines.
(3) Installations of railways for generation, transformation, trans-
mission or distribution of power used exclusively for operation of roll-
ing stock or installations used exclusively for signaling and communica-
tion purposes.
(4) Installations of communication equipment under exclusive
control of communication utilities, located outdoors or in building
spaces used exclusively for such installations.
(5) Installations under the exclusive control of electric utilities
for the purpose of communication, metering or for the generation,
control, transformation, transmission and distribution of electric energy
72-2 MASSACHUSETTS ELECTRICAL CODE
located in buildings used exclusively by utilities for such purposes or
located outdoors on property owned or leased by the utility or on
public highways, streets, roads, etc., or outdoors by established rights
on private property.
(c) Special Permission. The authority having jurisdiction for en-
forcing the Code may grant exception for the installation of conductors
and equipment, not under the exclusive control of the electric utilities
and used to connect the electric utility supply system to the service
entrance conductors of the premises served, provided such installations
are outside a building or terminate immediately inside a building wall.
90-3. Code Arrangement. This Code is divided into nine chapters.
Chapters 1, 2, 3 and 4 apply generally; Chapters 5, 6 and 7 apply to
special occupancies, special equipment, or other special conditions. The
latter chapters supplement or amend the general rules. Chapters 1
through 4 apply except as amended by Chapters 5, 6 and 7 for the
particular conditions.
Chapter 8 covers communications systems and is independent of the
other chapters except where they are specifically referenced therein.
Chapter 9 consists of tables and examples.
90-4. Definitions. Article 100 contains definitions of a number of
terms that are used in two or more Articles. In general, terms used only
in a single Article are defined in the Article concerned. For electrical
terms not defined in the Code, refer to the ANSI Standard Definitions
of Electrical Terms, ANSI C-42 series.
90-5. Fundamental Rules. Throughout the Code are paragraphs which
state only fundamentals or objectives of safeguarding. These are fol-
lowed by paragraphs setting forth the recognized methods and detail by
which the purpose and intent of the fundamental may be satisfied. Ac-
cordingly, when employed, the rules stating a fundamental only will
appear as the first paragraph of an Article or Section.
90-6.
DELETED
90—7. Enforcement'.
This code shall be used by the authority enforcing the code. The administrative
authority supervising such enforcement of the code shall have the responsi-
bility for making interpretations of the rules and shall accept approved or
labeled equipment and materials suitable for the purpose for which they are
to be used. He may decide on the approval of unlisted equipment and may
grant special permission contemplated in a number of the rules.
90-8. Examination of Equipment for Safety. For approval of specific
items of equipment and materials covered by the Code, examinations
for safety should be made under standard conditions, and the record
made generally available through promulgation by organizations prop-
erly equipped and qualified for experimental testing, inspections of the
