The 1999 National Electrical Code Summary

By Mike Holt

NEC Chapter 1 - General Requirements
NEC Chapter 2 - Wiring and Protection
NEC Chapter 3 - Wiring Methods and Materials
NEC Chapter 4 - Equipment for General Use
NEC Chapter 5 - Special Occupancy
NEC Chapter 6 - Special Equipment
NEC Chapter 7 - Special Conditions
NEC Chapter 8 - Communications Systems
NEC Chapter 9 - Tables

If you would like the detail information (with graphics) on the 1999 NEC, please consider ordering my best selling book, CD-ROM and/or Video "Illustrated 1999 National Electrical Code Changes". Call my office toll free 1-888-NEC CODE or email

Code Change Book

$ 35.00

Code Change CD-ROM

$ 99.00

Code Change Video

$ 99.00

Order all three for only


Article 90 – NEC Introduction

  • Permissive rules and purpose of Fine Print Note (FPN) clarified.


Article 100 – Definitions

  • "Feeder" definition revised to coordinate with the revised definition for "Service" and "Service Conductors."

  • "Multioutlet" definition revised to identify that a "Power Pole" is also considered a multioutlet assembly.

  • The term "Receptacle" clarified.

  • "Service" definition revised to coordinate with the revised definition for "Feeder" and "Service Conductors."

  • The term "Service Conductor" clarified.

Article 110 – General Installation Requirements

  • Article 110 reorganized and new parts added for under and over 600 volt installations.

  • The word "withstand" was replaced with the word "current."

  • The intent of "extensive damage" when applying "short-circuit current" rating rules was clarified.

  • Exceptions for conductor sizing based on terminal rating were rewritten into positive Code language.

  • Conductor size (for some motors) shall be based on 75°C conductor insulation rating.

  • Text revised to clarify the intent of field-marking for "series rated installations."

  • Working space rules reorganized into separate Sections.

  • Working space entrances can be locked if accessible to qualified persons.

  • Clear working space not required at the sides of equipment assemblies.

  • Width of working space might need to be more than 30 inches.

  • "Equal depth" rule revised to allow electrical equipment above or below one another.

  • Rules for "dedicated equipment space" for switchboards, panelboards, and motor control centers were revised and relocated to Section 110-26(f).


Article 200 – Use and Identification of the Grounded Conductor

  • Requirements for the identification of grounded conductors (neutral) editorially revised.

  • White or gray insulation no longer permitted for single-pole, 3-way, or 4-way switch loops.

Article 210 – Branch Circuits

  • Article 210 was reorganized to flow in a more logical order.

  • The requirements for the identification of multiwire branch circuit conductors were clarified.

  • GFCI protection rule for dwelling unit accessory building receptacles clarified.

  • GFCI protection is not required for dwelling unit snow-melting or deicing equipment receptacle.

  • Dwelling unit wet bar receptacles not permitted to be installed face-up in countertop.

  • GFCI protection is not required for rooftop snow-melting and deicing equipment receptacle.

  • New exception permits dwelling unit bathroom circuit to supply other loads.

  • New Section to require "Arc-fault Circuit Interrupter" (AFCI) protection for dwelling unit bedroom receptacles installed after January 1, 2002.

  • Requirement for sizing branch circuit conductors for continuous loads slightly revised.

  • Rules on the maximum load permitted on a 15 or 20 ampere branch circuit clarified.

  • Two small appliance branch circuits required for "each dwelling unit kitchen."

  • New rules clarify the placement of countertop space receptacles for dwelling unit kitchen or dining room.

  • The words "adjacent to each basin" requiring installation of dwelling unit bathroom receptacle were removed.

  • Revised text requires a GFCI-protected 125 volt, 15 or 20 ampere receptacle in the unfinished portion of a one-family dwelling unit basement.

  • New requirements on placement of hotel and motel guest room receptacles.

  • New text clarifies that dwelling unit bathroom requires a wall switch-controlled lighting outlet.

  • New text clarifies the installation of the dwelling unit lighting outlet at exterior entrances and exits.

  • New text clarifies that pull-chain fixtures can be used for dwelling unit lighting in storage and equipment spaces.

Article 215 – Feeders

  • Article 215 was reorganized so that the requirements flow in a more logical order.

Article 220 – Branch Circuit, Feeder, and Service Load Calculations

  • Article 220 was reorganized so that the requirements would flow in a more logical order.

  • The rule for rounding an ampere was relocated from Chapter 9 to Section 220-2.

  • 180 VA rating for commercial and industrial general purpose receptacles revised to cover multiple-receptacle equipment.

  • Rules for track lighting relocated and clarified.

  • Rules for "two dissimilar loads" clarified.

  • Optional load calculations for dwelling unit revised to clarify the requirement.

  • Examples from Chapter 9, Part B relocated to a new Appendix D.

  • Chapter 9, Part B. Examples

Article 225 – Outside Branch Circuits and Feeders

  • Overhead conductors above platforms, projections, or other surfaces shall not be within reach.

  • The requirement for multiple building disconnecting means was revised and relocated to a new Part B.

  • The condition of when a "conductor is outside of a building" was expanded to include feeder and branch circuit conductors.

  • Exception revised to clarify that safe switching, is the important safety issue, not the type of facility.

  • New exception clarifies that a sign structure disconnecting means shall comply with the rules for signs in Article 600, not the requirement in Article 225.

Article 230 – Services

  • Overhead service conductor above platforms, projections, or other surfaces shall not be within reach.

  • Continuous load rule on sizing of service conductors now contained in Article 230.

  • Rules governing the splicing of service conductors editorially revised.

  • The rule for the protection of service-entrance conductors or cables was editorially revised.

  • Revised rule clarifies that "each" service disconnect shall be permanently marked to identify it as a service disconnect.

  • The rule on the maximum number of service disconnects was revised to remove the conflict between other Code Sections.

  • Revised text clarifies that an "emergency system" cannot be supplied from the "normal service."

  • The sum of the ratings of the service equipment can exceed the ampacity of the service conductors.

  • Accessibility of the service overcurrent protection device clarified.

Article 240 – Overcurrent Protection

  • Rules for overcurrent protection of No. 14, No. 12, and No.10 clarified.

  • The definition of a tap conductor was added to the 1999 Code.

  • New rules clarify that a tap conductor cannot be tapped.

  • Section 240-21 was revised to distinguish the requirements for tap and transformer secondary conductors.

  • New Part H added to Article 240 to cover overcurrent protection for supervised industrial installations not over 600 volts.

  • New Part I. Overcurrent Protection Over 600 Volts added to 1999 NEC

Article 250 – Grounding

  • Article 250 reorganized.

  • New Appendix E provides cross-references for Article 250.

  • Rules for grounding of services revised and clarified.

  • Grounding and bonding of separately derived systems revised and clarified.

  • Grounding and bonding of separate buildings or structures revised and clarified.

  • Supplemental electrode for underground water pipe electrode shall have a resistance of 25 ohms or less, or two ground rods are required.

  • New text clarifies that concrete-encased electrode (Ufer) need not be continuous.

  • Lightning protection air conductors or electrodes shall not be used as the required grounding electrode for the building/structure.

  • Bonding for communications systems was editorially revised.

  • Rules revised to clarify the bonding requirements for service cables, raceways, enclosures, and cables.

  • Rules for grounding of 480Y/277 volt circuits clarified.

  • New rules clarify the method of bonding interior metal water piping systems at separate buildings.

  • The bonding requirements for interior gas pipes from NFPA 54 - National Electrical Gas Code was added to the 1999 NEC.

  • Rules on bonding the lightning protection system to the building grounding electrode system clarified.

  • Grounding of prefabricated electrical equipment on metal skids now covered by the NEC.

  • Rule for parallel equipment grounding conductors was revised to accommodate undersized equipment grounding conductor in listed cables.

  • Grounding conductor sized according to Table 250-122 might not be large enough to safely carry ground-fault current.

  • Rules on replacing nongrounding-type receptacles if no grounding conductor exists in the outlet box were revised.

  • Rule for receptacle equipment bonding jumper for recessed installations revised.

Article 280 – Surge Arresters

  • The exception was editorially rewritten into positive language.


Article 300 – Wiring Methods

  • New language clarifies when the rules of Article 300 apply to low-voltage and limited-energy wiring.

  • Nonmetallic cable shall be completely protected when run through metal framing members.

  • Warning ribbon required for service raceways and cables buried 18 inches or more.

  • Rule that prohibits the use of suspended ceiling framing and it's support wires to support electrical wiring further revised in the 1999 NEC.

  • Rules on length of free conductors at outlets, junction, and switch points further clarified.

  • New rules clarify the use of terminating conductors at a bushing instead of an enclosure.

  • New exception recognizes listed prewired assemblies.

  • Section 300-18(a) (New)

  • New rules prohibit welding metal raceways for support.

  • Fine Print Note revised to recognize that 24-inch separation between outlet boxes in fire rated assemblies is not always required.

  • New text permits electrical metallic tubing to be used for over 600 volt circuits.

Article 305 – Temporary Wiring

  • New rules clarify the use of open feeder conductors for temporary electrical power and lighting for emergencies and for tests, experiments, and developmental work.

  • Revision clarifies that nonmetallic-sheathed cable can be used for temporary wiring in buildings or structures above three floors.

  • New rule allows open branch circuit conductors for temporary Christmas and holiday lighting.

  • New Code Section contains the rules on the support requirements for cable assemblies used for temporary wiring.

  • GFCI protection requirements for receptacles used for temporary power are more stringent.

Article 310 – Conductors for General Wiring

  • Fine Print Note for parallel conductors incorporated as an NEC requirement.

  • Ampacity Notes from Table 310-16 relocated to Section 310-15 so they can be more usable.

  • 1999 NEC clarifies the intent of service and main power feeder conductor sizing when using Section 310-15(b)(6) for dwelling units.

Article 318 – Cable Trays

  • The definition of a cable tray was revised to better describe its purpose.

  • New rule clarifies that outlet boxes can be secured to a cable tray system.

Article 331 – Electrical Nonmetallic Tubing

  • Electrical Nonmetallic Tubing now permitted under a concrete slab.

  • New Code Section permits prewired electrical nonmetallic tubing.

Article 333 – Armored Cable (Type AC)

  • Cable ties and support wires permitted to secure AC cable.

Article 336 – Nonmetallic-Sheathed Cable (Type NM)

  • Nonmetallic-sheathed cable is permitted in one- and two-family dwellings of any height. Nonmetallic-sheathed cable cannot be installed in multifamily and other structures over three floors.

  • Support not required for nonmetallic-sheathed cable whips for the connections to lighting fixtures and equipment within accessible ceilings.

  • New Section added to contain the ampacity requirements for the nonmetallic-sheathed cable.

Article 338 – Service-Entrance Cable

  • New Section should clear up the misunderstanding on the use of Type SE cable for exterior installations.

Article 339 – Underground Feeder and Branch Circuit Cable (Type UF)

  • New Code rule specifies that UF cable shall not be used where subjected to physical damage.

Article 343 – Nonmetallic Underground Conduit with Conductors

  • New sentence clarifies that bends for nonmetallic underground conduit with conductors shall be made in accordance with the new Table 343-10.

Article 347 – Rigid Nonmetallic Conduit (PVC)

  • New rules clarify that PVC can be used to support conduit bodies, but only if the conduit body does not contain lighting fixtures or other equipment.

  • An equipment grounding conductor is not always required within rigid nonmetallic conduit.

  • Thermal expansion and contraction table for rigid nonmetallic conduit relocated from Chapter 9, Table 10 to Section 347-9.

Article 351 – Liquidtight Flexible Nonmetallic Conduit

  • New Section permits listed manufactured prewired liquidtight flexible nonmetallic assemblies.

Article 362 – Metal and Nonmetallic Wireways

  • Rules attempt to clarify how to properly size a wireway when conductors enter and exit.

Article 364 – Busways

  • New rule requires 4-inch curb around floor opening for a busway riser that penetrates two or more floor openings.

Article 370 – Outlet and Device Boxes

  • Conductor-fill calculations for domed canopy lighting fixtures clarified.

  • New rules clarify that suspended ceiling framing members and independent support wires can support outlet boxes.

  • Support of small lighting fixtures to device box with No. 6/32 screws now permitted.

  • New Part D added to Article 370 to contain the requirements for underground manholes and vaults used by personnel.

Article 373 – Cabinets, Cutout Boxes, and Meter Socket Enclosures

  • New exception permits the sleeving of NM cable into a surface-mounted panel without individual cable connectors.

Article 380 – Switches

  • New rule permits using switch and circuit breaker enclosures for splices, taps, and conductors feeding through.

  • All "snap switches" shall be effectively grounded.

Article 384 – Switchboards and Panelboards

  • Dedicated electrical space rules relocated to Section 110-16(f).

  • Classification of panelboards revised to include both lighting and appliance panelboard and a power panelboard.

  • New rules for panelboard overcurrent protection added to accommodate the new requirement for a power panelboard.

  • Rules for securing back fed circuit breakers that contain field-installed ungrounded conductors clarified.


Article 400 – Flexible Cords and Cables

  • New language clarifies that cords cannot be installed through suspended ceiling tiles.

Article 410 – Lighting Fixtures and Receptacles

  • New text clarifies bathtub zones and shower space rules for the installation of lighting fixtures.

  • Metal poles for lighting fixtures cannot contain low-voltage or limited-energy circuits.

  • New rule permits lighting fixtures "over 50 pounds" to be supported to a box or fitting listed for the weight.

  • Lighting fixtures may be attached to suspended ceiling framing with clips "listed" for this use.

  • Rules on isolated ground receptacles in nonmetallic boxes with metal plates revised.

  • Receptacle mounted to a cover shall be secured with two screws.

  • Rules for receptacle covers in wet locations revised to clarify the intent.

  • The minimum length of light fixture tap conductors was reduced from 48 inches to 18 inches.

  • Track lighting rule attempts to coordinate with revised Section 410-4(d), but it doesn't.

  • Rules for track lighting feeder/service load calculations relocated to Section 220-12.

Article 422 – Appliances

  • Article 422 was rearranged into a more logical order, and many of the Sections have been renumbered.

  • New Code rules added to cover central vacuum receptacle outlet.

  • Revised rule makes legal the generally accepted practice of using a 6-foot cord for a dishwasher.

  • Outlet boxes can now be used to support suspended ceiling fans that weigh up to 70 pounds, if listed for this purpose.

Article 424 – Fixed Electric Space-Heating Equipment

  • GFCI protection required for heating cables in floor of bathrooms and hydromassage bathtub, spa, and hot tub locations.

Article 426 – Outdoor Deicing and Snow-Melting Equipment

  • Ground-fault protection requirements for deicing and snow-melting equipment clarified.

Article 427 – Heating Equipment for Pipelines and Vessels

  • Ground-fault protection rules for electric heat tracing and heat panels clarified.

Article 430 – Motors

  • Scope of Article 430 clarified by relocation of text of the exceptions into a new Fine Print Note.

  • 1999 NEC clarifies the rules on motor calculations.

  • New FPN reminds the Code user to properly protect motor relays that have low short-circuit current rating.

  • New text clarifies that motor branch circuit conductors shall be sized to the motor’s FLC rating, not the motor’s nameplate current rating.

  • New text clarifies that motor feeder conductors shall be sized to the motor FLC rating, not the motor nameplate current rating.

  • Requirements on how to prevent personal injury due to automatic motor restarting revised to clarify the intent of the rule.

  • New rule permits molded case switch (nonautomatic circuit breaker) to be used as a motor controller.

  • Motor disconnecting means is not required to be within sight of motor, if...

Article 445 – Generators

  • New Code rule ensures proper size enclosure for generator terminal housing.

  • New Code Section requires disconnecting means on the supply side of generators.

Article 450 – Transformers and Transformer Vaults

  • Section 450-3 was completely rewritten to simplify transformer overcurrent protection.

  • "Readily accessible" requirements for transformers clarified.

Article 480 – Storage Batteries

  • Working space requirements added for storage batteries.

Article 490 – Equipment, Over 600 Volts, Nominal

  • New Article for over 600 Volt equipment added.


Article 500 – Hazardous (Classified) Locations

  • Move all material related to Zone Systems installations from Article 500 to Article 505.

  • Hazardous (classified) locations shall be properly documented.

Article 501 – Class I Hazardous (classified) Locations

  • Type ITC cables now permitted to be installed in industrial Class I, Division 1 locations.

  • New text specifies that the boundary seal for Class I, Division 2 locations shall not be more than 10 feet from the boundary.

  • To comply with product listing requirements, percent fill limitations for seals shall not exceed 25 percent of the cross-sectional area of a "rigid metal conduit," even if intermediate metal conduit is used.

  • New Exception relaxes the sealing requirements for Type MC cable containing low-voltage and limited energy conductors in Class I, Division 1 locations.

  • Rules relaxed for sealing low-voltage and limited energy cables in Class I, Division 2 locations.

Article 505 – Class I, Zone 0, 1, and 2 Hazardous Locations

  • Zone classification rules rewritten so that all rules are incorporated into one Article.

  • Zone (classified) systems shall be supervised by a "Qualified Registered Professional Engineer."

Article 514 – Gasoline Dispensing and Service Stations

  • Gasoline dispensers must be electrically isolated from each other.

Article 517 – Health Care Facilities

  • Safety ground required for metal switch yokes located within the patient care area.

  • Patient bed receptacles can be supplied from emergency system transfer switches.

  • New rule permits tamper resistant protection for receptacles located in the patient care areas of pediatric wards, and rooms to be by either a tamper-resistant receptacle or cover.

  • Figure 517-30(a) and (b) modified to label the Life Safety and Critical Branch automatic transfer switches as part of the Emergency System.

  • Life Safety Branch not permitted to be shed upon generator equipment overloading.

Article 518 – Places of Assembly

  • Audience-seating areas are included in "theatrical areas" as referenced in Section 518-2(c).

  • Flexible metal raceway and armored cable permitted in places of assembly.

Article 525 – Carnivals, Circuses, Fairs, And Similar Events

  • Overhead conductor clearance within tents permitted to be reduced.

  • Flexible cords or cables installed inside rides or concessions do not need to be listed for wet locations or sunlight resistance.

  • New rule permits cord connectors to be laid on the ground in wet locations, but not where they could be a tripping hazard.

  • New text restricts the supporting of overhead conductors by tent posts.

  • Lighting inside tents shall be installed so that it is not subject to physical damage.

  • New rules require GFCI protection for 125 volt, 15 and 20 ampere receptacles.

  • Attractions using large volumes of water shall comply with the requirements of Article 680 – Pools and Fountains.

Article 547 – Agricultural Buildings

  • Section 547-8 was retitled with some requirements rewritten or relocated.

  • Equipotential plane rules clarified and now relocated to a new Section 547-9.

  • GFCI protection required for all 125 volt, 15 and 20 ampere receptacles installed in areas having an equipotential plane.

Article 550 – Mobile Homes, Manufactured Homes, and Mobile Home Parks

  • Definition of Manufactured Home has been revised.

  • The heating cable receptacle outlet for mobile and manufactured homes shall be GFCI-protected.

  • Service equipment rules for mobile homes and manufactured homes clarified.

  • Mobile and manufactured home service disconnect shall not be higher than 6 feet, 7 inches.

  • Mobile home service load calculations example from Sections 550-13 relocated to Appendix D.

Article 551 – Recreational Vehicles and Recreational Vehicle Parks

  • Distribution system voltage of 208Y/120 volt, three-phase systems now permitted for recreational vehicles parks.

Article 555 – Marinas and Boatyards

  • Disconnect required so that each boat can be isolated from its supply.

  • Three significant changes were made for marina feeder/service load calculations.


Article 600 – Sign and Outline Lighting

  • New text requires sign disconnect for a sign installed within a fountain to comply with the requirements of Article 680.

  • Sign disconnect rules revised and clarified.

Article 620 – Elevators

  • Overcurrent protection device for elevator car light receptacle(s), auxiliary lighting, and ventilation shall be located in elevator machine/machinery space.

  • The overcurrent protection device for each elevator car air-conditioning unit shall be located in the elevator machine room/machinery space.

  • GFCI protection requirements for elevator personnel revised.

Article 625 – Electric Vehicle Charging System Equipment

  • GFCI protection no longer required for electric vehicle supply equipment.

Article 640 – Sound-Recording And Similar Equipment

  • Article 640 was rewritten to accommodate current electronic audio practices.

Article 645 – Information Technology Equipment (Data Processing Room)

  • Rules for low-voltage and limited-energy wiring in raised computer floor incorporated into general requirements.

  • New rule permits single insulated green bonding conductor within computer raised floor area.

Article 680 – Swimming Pools, Fountains, Spas, Hot Tubs and Hydromassage Bathtubs

  • Revised exception permits receptacle within 10 feet of water.

  • The clearance requirements for overhead conductors over pools, spas, and hot tub areas were modified.

  • Changes clarify that a disconnecting means is required for pool, spa, and hot tub equipment.

  • Pool junction box connected to a conduit that extends directly to a pool light forming shell shall be listed for the use.

  • Transformer or ground-fault circuit-interrupter enclosure connected to a conduit that extends directly to a pool light forming shell shall be listed for this purpose.

  • The No. 8 bonding conductor of pool equipment need not be extended to service equipment.

  • Nonconductive reinforcing steel rebar does not need to be bonded.

  • Section 680-22(a)(1), (New)

  • New rule requires the No. 8 bonding terminations to be terminated by exothermic welding or pressure connector labeled for the purpose.

  • The requirement to ground listed low-voltage pool systems was eliminated.

  • Liquidtight flexible nonmetallic conduit is a permitted wiring method for pool lighting fixture wiring.

  • Chapter 3 wiring methods can now be used for pool-associated motors located at any building associated with a one-family dwelling.

  • New rules added to clarify the grounding requirements of feeders to separate buildings or structures that supply pool equipment.

  • Liquidtight flexible nonmetallic conduit and electrical nonmetallic tubing permitted for feeder raceway.

  • New Section requires readily accessible emergency shut-off within sight of commercial spas or hot tubs.

  • Junction box for fountain light forming shell shall be listed for the purpose.

  • New rules added to cover for electric signs installed within fountains.

  • GFCI protection rules for 125 volt single-phase receptacles located near hydromassage bathtub clarified.

  • New rule requires access to hydromassage bathtub equipment.

Article 695 – Fire Pumps

  • Article 695 was rewritten so the text complies with NFPA Extract Policy.

  • New rules clarify how to size conductor for fire pump motors.

  • Voltage drop rules relocated and changed to clarify the intent.


Article 700 – Emergency Systems

  • New text clarifies the intent on the use of transfer switches for emergency circuits.

  • Rules for maintaining independent wiring for emergency systems revised so as to be more easily understood.

Article 710 – Over 600 Volts, Nominal, General

  • The text contained in Article 710 was relocated to other Articles in Chapter 1 through 4 as well as a new Article 490.

Article 727 – Instrumentation Tray Cable

  • Article 727 was rearranged to comply with Code Style Manual.

Article 760 – Fire Alarm Systems

  • Splices and terminations of nonpower-limited fire alarm circuits shall be made in proper enclosures.

Article 770 – Optical Fiber Cable

  • Raceways for optical fiber cables, except listed nonmetallic optical fiber cable raceways, shall be installed in accordance with the requirements of Chapter 3.


Article 800 – Communications Circuits

  • Communications equipment shall comply with Section 110-3(b).

  • Raceways for telephone wiring, except listed nonmetallic communication raceways, shall be installed in accordance with the requirements of Chapter 3.

  • New listed communications raceways permitted in ducts, plenums and other spaces used for environmental air.

Article 810 – Radio and Television Equipment

  • The scope of Article 810 was expanded to include current antenna technology products.

Article 830 – Network-Powered Broadband Communications Systems

  • New Article contains the requirements for Network-Powered Broadband Communications Systems.

NEC Appendix D – Examples

  • The examples that were contained in Part B of Chapter 9 have been relocated to a new Appendix D.

  • Motor example was revised to make it more readable and easier to understand.

If you would like the detail information (with graphics) on the 1999 NEC, please consider ordering my best selling book, CD-ROM and/or Video "Illustrated 1999 National Electrical Code Changes". Call my office toll free 1-888-NEC CODE or email

Code Change Book

$ 35.00

Code Change CD-ROM

$ 99.00

Code Change Video

$ 99.00

Order all three for only


Copyright ©2002 Mike Holt Enterprises
All rights reserved


  Go to top of page
Newsletter Registration   |   Stay Connected:

888.NEC.CODE (632.2633) 3604 PARKWAY BLVD, STE 3, LEESBURG FL 34748  

Tell a Friend About This Site

  NEC® and National Electrical Code® are registered trade marks
of the National Fire Protection Association (NFPA).
  ©Copyright 2011 Mike Holt Enterprises, Inc.