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National Electrical Code
NFPA-70
2016 Montana Joint Engineers
Council Meeting
By Dan Battleson, PE, PMP, UTRS, Inc
Bonus Question??? --$5
• Trivia-When and why did rigid
steel conduit begin as a wiring
method??
TRAGIC EXAMPLE
•MGM GRAND1980 Las Vegas,
Nv—87 persons
killed, 650
injured
MGM Fire-Nov.--1980
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6 year old installation
120 V single phase circuit
No EGC pulled for grounding redundancy
Fatal flaw in using flex aluminum conduit
Partially grounded system
Vibration from deli cooler compressor
MGM Fire-Nov.--1980
• Galvanic action Cu-AL resulting from flex
conduit rubbing against copper tubing from
compressor—Code violation
BIO
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MSU-- BS EE 1970—46 years
Anaconda Co.-Gt Falls, MT
5 yrs Bell Tel. System—US Navy Support Program
PE-MT -- Mstr. Elect. Lic.—1978, PMP-1991
Electrical Contractor, Boeing Co, CED- Contr.
Sales
• 31 years @ MSE-TA, EE, Sr. Manager-VP
Engineering
• 6 UTRS, Inc, SME--- Elect. Eng, Electrician
History and Origin
• Originally developed in 1897 in NYC by ASME
• Need was driven by increasing electrical fires
• National Standard from 5 different existing
codes, German and UK references
• Now all 50 states, US territories, and US
foreign facilities incorporate NEC
About the NEC
• Living document—Updated Every 3 years
• Anyone may submit proposal input to ongoing
code committees. (Public, Industry,
Electricians, Engineers, etc.)
• Open Consensus process
• Practical safeguarding of persons and property
Article 90 Introduction
• Practical Safeguarding of persons and
property, not intended to be a design,
specification, or instruction manual
• Intended to be incorporated as a statute
• 19 Code-making committees, each assigned
specific code article responsibility
• Updated every 3 years, 2014 is current
• Correlated to 8 other NFPA related standards
including NFPA 70E—worplace safety
ARTICLE 90 (continued)
• Addresses fundamentals of IEC 60364-1,
Section 131 (Elect. Installations of Buildings)
• SCOPE- Covered--public and private premises,
RV’s, mobile homes, Boat houses, yards, lots
carnivals, industrial substations, any
equipment supplied by electricity. Utility
offices, warehouses, garages, etc.
Article 90(continued)
• SCOPE - Not covered—Ships, watercraft,
railways (rolling, signaling, communications),
aircraft, autos, mines, mobile mine
machinery, communications building under
exclusive control of utility (outdoors or
buidings under exclusive control),
NEC Arrangement
• Chapters 1-4, Wiring and Protection, Wiring
Methods and Materials, Equipment for
General Use (Applies for all electrical
Installations)
• Chapters 5-7, Special Occupancies, Special
Equipment, Special Conditions (Enhances or
Modifies Chapt. 1-4)
NEC Arrangement (Cont’d)
• Chapter 8-Communications Systems-Not
subject to req’mts of Chapt.1-7, unless
specifically referenced in Chapter 8
• Chapter 9—Tables (Excellent reference mat’l)
• Informative Annex A-J—Information only not
part of enforceable Code but very useful
• Material, Equipment listing, labeling—UL or
other 3rd party certification entity.
Chapter 1- General
• Definitions and Requirements for Electrical
Installations
• Practical guidelines for workmanship as
related to safely maintaining or modifying the
electrical system
• Approval—Authority Having Juristiction (AHJ)
as mandated by State and Local Statute, i.e,
the Electrical Inspector.
Chapter 1 Changes
• New: 110.14 (D)— Mandatory use of torque
tool
• New:110.16 (B)—Arc Flash Hazard warning
information, system voltage, flash boundary,
available incident energy, PPE
• New--110.16 Arc-Flash Warning Label—more
detailed information, PPE, No unqualified
persons, etc.
Chapter 1 Changes
• New--110.21 (A)(2)—Reconditioned
Equipment—Mark to identify the vendor that
performed the reconditioning.
• New--110.26 (A)(4)—Working space—Limited
access-will allow exceptions in ceilings and
crawl spaces where compliance is not
presently feasible.
• New--110.26 (A)(4)—Clear Space signs
required
Chapter 2-Wiring and Protection
• Branch circuits, Feeders, Services, Overcurrent
protection (thermal mag.), Grounding &
bonding: Art. 250
• --Difference between “grounded” conductor
and “grounding” conductor, commonly used
color code used for each???!
• --Separately Derived Systems-Gen, Batt, Solar,
Wind, Xformers,
Chapter 2, Changes
• Revision-210.8(A)—GFCI Protection-Dwelling
Units-expand to all 120 v and 250v outlets,
i.e., table saws, 250 v tools. Dryer outlets
excluded.
• New--210.8(B)(2)(a)—SPGFCI Protection-20
ma trip, special purpose— i.e., 3 phase 480
volt welding outlets.
• New--210.11(C)(4)—Dwelling Units—Garage
Branch Circuits—at least one 20 amp, 125 v
branch circuit required.
Chapter 2, Changes
• Revision-210.12(A)—100 % AFCI Protection—
all 120 v circuits.
• New--210.71—Meeting Room Receptacles—
requirement is similar to dwelling unit
• Revision-230.29—Overhead Service
Conductors—ConductorSupports over
buildings—bonding to grounded conductor
required, same size.
Chapter 2, Changes
• New--240.67—Arc Energy Reduction (1200
amp and greater Fusible Switches)—Similar to
present 1200 amp breaker requirements, 1
Jan 2020.
• Revision-250.30(A)(4)—Grounding Sep. Drv.
AC Systems—GES—Eliminates “pecking order”
from nearest metal water pipe/structural steel
to any electrodes in 250.52(A). Also defines
pipe and steel as conductors
Chapter 2, Changes
• Revision-250.52(A)(2) Metal In-Ground
Support Structure-to qualify only 1
condition—10 feet direct contact with earth
• New-250.52(B)(3)-Not permitted as G.E.’sStructural swimming pool reinforcing steel or
steel pool shell not allowed to be used
grounding electrodes for outbuildings being
fed by a feeder per 250.32(A)
Chapter 3-Wiring Methods and
Materials
• Premises wiring, not integral parts of
equipment
• Conductors, Outlet Boxes, Cabinets, Meter
Bases, Conduit, raceways, etc
• Wire ampacities, voltage drop rules (gen. 3%)
• Conduit fill (gen. 40% limit), attachment and
support rules
• 1000 V gen. guideline vs. 600V (Solar panels)
Chapter 3, Changes
• Table 310.15(B)(7)—Sizing Dwelling Unit
Services and Feeders—120V/208V 3 phase
systems being considered. Will allow
downsizing service neutral conductor as is
presently allowed for 120V/240V. Could be a
problem if only 2 hot legs are used with 208.
• New--314.27(E) Outlet Boxes—Separable
Attachment Fittings—new fittings for paddle
fans attach to listed support boxes.
Chapter 3, Changes
• New-320.6—Listing Requirements- Types AC,
and appropriate section of FC, FCC, MV, MC,
MI, NM, TC, SE, UF. Ensures listed
termination fittings match these cables.
• 366.20 Auxiliary Gutters—Concuctors
Connected in Parallel
Chapter 4-Equipment for General Use
• Cords and cables
• Switches, receptacles, connectors
• Switchboards, Switchgear, Industrial Control
Panels (UL 508A)
• Luminaires, lampholders, and lamps
• Appliances (circuits, wiring rules), Elect. Heat,
Motors, HVAC, Xformers, Capacitors, Batteries
Chapter 4, Changes
• New-404.22—Switches w/ power supplies,
light dimmers, etc—must pull neutral wire
• New-Article 425—Fixed Resistance and
Electrode Industrial Process Heating
Equipment—specific requirements for boilers,
electrode boilers, duct heaters, strip heaters,
immersion heaters, process air heaters.
Personnel HVAC excluded, covered elsewhere.
Chapter 4, Changes
• Revision-406.12 Tamper Resistant Receptacles
Expanded to pre-schools corridors, dental
offices, Med offices, etc.
• Revision-408.3 (A)(2)—Safety barriers for live
bus, expanded to Service panelboards.
• New-409.23-Avail Fault Current marking req’d
for Indutrial Control Panels
Chapter 5-Special Occupancies
• Hazardous Locations
• US—Class I—Refineries, flammable vapors, etc
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Class II—Coal processing, grain
processing
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Class III—Textile industry, flying fibers
• IEC—Zones-0, 1, 2, 3
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Zones-20,21,22
Chapter 5, Spec. Occ,Con’t
• Comm. Garages, Aircraft Hangers, Motor fuel
dispensing, Bulk Storage, Auto painting
• Health care, theaters, TV studios, Carnivals
• Manufactured Buildings, Agricultural Buildings
• Mobile homes, floating buildings, marinas and
boatyards
• Temporary installations—example:
construction sites
Chapter 5, Changes
• Revision-501.10(B)(1)-Wiring methods-now
allows listed threadless fittings for RMC, IMC,
and added EMT.
• New—Tables 511.3 (C)(D) Repair garage tables
revised to classify boundaries easier.
• Revision-517.2—New definitions added for
clarifications, “Gov body”, Medical areas more
defined.
Chapter 6-Special Equipment
• Electric Signs, Manuf. Wiring systems (plug in
busways), Cranes, Hoists, Elevators, Platform
lifts, Stairway chairlifts
• Electric Vehicle Charging Systems, Welders,
Audio Systems, IT Equipment, Modular Data
Centers
• Pipe Organs, X-ray Equip., Industrial
Machinery, Swimming pools, PV, Wind, Fuel
Cells
Chapter 6, Changes
• New- 600.34—Solar powered signs now
covered
• Revision-690.8(A)(1)-PV short circuit
calculations to be performed by qualified PV
design engineer
• New-695.15- Listed Surge protection now
required for fire pumps
Chapter 6, Changes
• New-Article 691—Large Scale Photovoltaic
(PV) Electric Supply Stations—supply power at
the utility level (Distribution), also called solar
farms or utility-scale solar system. Eliminate
AHJ professional risk, allow engineering best
practices to be used in the design
• Revision-625.1-EV chargers now include
inductively coupled
• Revision-630.6 Welding Equipment now must
be listed.
Chapter 6,
• Revision-690.2 –Clarification PV systems not
generally solidly grounded, i.e., no grounded
conductors upstream of the inverter.
• Revision-690.7 Maximum PV voltages
• 600 V—1 and 2 family dwelling units
• 1000V-all other occupancies
• 1500V—not attached to the building
Chapter 6, Revisions
• Revision-690.12 (B) PV Rapid shutdown inside
PV boundary, i.e., 1 foot from array voltage
must reduce conductor voltage to 30 volts
within 30 sec of RS initiation. Outside
boundary reduce to 80 volts.
• Revision-690.12 (C) PV rapid shutdown
initiation device (listed)
Chapter 7-Special Conditions
• Emergency Systems, Standby power, PV, Gen,
Wind, etc. interconnection systems.
• Critical operations systems (COPS)-Police
stations, fire stations, hospitals
• Less than 50V systems-DC lighting,
receptacles, etc.
• Class 1, 2, 3, control, signaling, power limited
circuits—some computer, fire alarm, Op. fiber
cables and raceways
Chapter 7 Changes
• Energy storage systems (ESS’s), batteries, flow
batteries, capacitors, flywheels, compressed
air.
• New— Article 712Direct Current Microgrids—
direct utilization of power from DC sources to
DC loads—LED’s, communications equip.,
computers, servers, VFD’s, HVAC—saves
energy vs. AC coupled methods.
Chapter 7, Changes
• New 700.25—Allows regular branch circuit
lighting circuits to be transferred to
emergency branch circuit using listed Xfer
switch.
• Revision-770.24 Requires fiber optic cables to
be protected against physical damage
according to all of 300.4.
Chapter 8-Communications Systems
• Radio and TV, community antenna TV and
radio systems, network powered broadband
communications.
• Premises wired Broadband communications
Chapter 8, Changes
• Revision-848.48—Premise powered
broadband communications--Recognizes
unlisted twisted pair and coaxial cablesystems in addition to fiber based systems.
Chapter 9-Tables
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12 Tables
Conduit Fill
Conduit bend raduis
More specifics on conduit fill
Wire Dimensions
Conductor properties—Dia, R, Z @ .85 PF,
Inductive reactance
Annex’s A-J
• Informative only, not part of NEC
requirements.
• Product safety standards list UL, ANSI, NeherMcGrath ampacity formula, Conduit fill tables
• Load calculation examples, including VFD
example
• NFPA types of construction, Availability and
Reliability calcs. for Crit. Power systems
Annex con’t
• Supervisory Control and Data Acquisition
(SCADA) requirements
• Administration and Enforcement—model set
of rules that could be incorporated into laws
in part or full to be enforced by local and state
Authorities having jurisdiction (AHJ’s)
• Latest NEC is for new construction, existing
construction is generally exempt from the 3
year update of the NEC.
Annex con’t
• Torque values for electrical terminations—UL
486A
• American Disabilities Act (ADA) Standards for
Accessible Design.