NEC Code Tips

Article 200 – Use and Identification of Grounded (Neutral) Conductor

April, 2000

Tip #24 Identification of the Grounded Conductor [200-6]

Grounded (neutral) conductors No. 6 and smaller must have a continuous white or natural gray outer finish along their entire length, and white reidentification tape, paint, or other methods of markings is not permitted.

Grounded (neutral) conductors larger than No. 6 can be identified by distinctive white markings such as tape, paint, or other effective means at the wire terminations.

Note: Reidentification can be with white phase tape, but not with gray phase tape!

Where conductors of different systems are installed in the same raceway or enclosure, one system grounded (neutral) must have an outer covering of white or gray and the other system grounded (neutral) conductor, must have an outer covering of white with a readily distinguishable different color stripe (not green) running along the insulation.

Note. Proposals to permit the color white and gray for grounded (neutral) conductor identification when circuits for different voltage systems are contained within the same raceway, cable, or enclosure were rejected. The Code Panel felt that the colors white and gray are not always readily distinguishable from each other and should not be used to identify the different system grounded (neutral) conductors when installed in the same raceway, cable, or enclosure.

Tip #25 Use of White or Natural Gray Conductor Finish for the Hot Wire [200-7]

Raceway. White or natural gray conductor finish, tape, or paint can be used only for the grounded (neutral) conductor. The 1999 NEC does not permit the white or gray conductor to be used for power conductors, even if permanently reidentified.

Cable Assembly. White or gray conductor within a cable assembly can be used for the ungrounded conductor, but the white or gray conductor must be permanently re-identified to indicate its use as an ungrounded conductor at each location where the conductor is visible and accessible.

Switches. White or gray conductor within a cable assembly used for single-pole, three-way or four-way switch loops must be permanently re-identified to indicate its use as an ungrounded conductor at each location where the conductor is visible and accessible.

Note. The 1996 NEC permitted white or natural gray insulated wire as an un-grounded (hot) conductor for single-pole, three-way and four-way switches without reidentification.

Tip #26 Terminal Identification [200-9]

Terminals for the termination of the grounded (neutral) conductors must be white in color (really silver because of the metal). The terminals for the termination of the ungrounded conductors must be a color that is readily distinguishable from white (often a brass or copper color). The terminal for the equipment grounding conductor must be a green hexagon-headed or hexagon shaped terminal screw [250-119].

Article 210 – Branch Circuits

  Tip #27 Branch circuit Rating [210-3]

The rating of a branch circuit is determined by the maximum rating or setting of the circuit overcurrent protection device. For example, the branch circuit rating of No. 10 THHN (rated 40 ampere, Table 310-16) on a 20 ampere circuit breaker is 20 ampere.

Tip #28 Multiwire Branch Circuits [210-4]

A multiwire branch circuit can be considered as one circuit, or it can be considered as two or three separate branch circuits. For example, the NEC requires two small appliance circuits for the dwelling unit kitchen counter receptacles [210-52(b)(2) and 210-11(c)(1)]; one 20 ampere, 120/240 volt multiwire branch circuit can be used for this purpose.

To prevent inductive heating and to reduce conductor impedance for fault-currents, all conductors of a multiwire branch circuit must originate from the same panelboard. See Sections 300-3(b) and 300-20(a) for more details on inductive heating.

Where more than one nominal voltage system exists in a building, each ungrounded conductor of a multiwire branch circuit, where accessible, shall be identified by phase and system. The identification can be by color coding, phase tape, tagging or other approved means. The method used for conductor identification must be posted at each panelboard. Most inspectors require the identification to be posted on the outside of the panelboard.

Note. If two system voltages do not exist in a building, then multiwire branch circuit identification is not required. However, identifying the branch circuit conductors is a common practice and at times a requirement of a local electrical code.

  Tip #29 Receptacles [210-7]

Only grounding type receptacles can be installed on 15- and 20 ampere branch circuits and they must have the grounding terminals properly grounded to the branch circuit equipment grounding conductor [250-146]. Failure to connect the receptacle’s grounding terminal to the equipment grounding conductor could lead to death or electrical shock. See Sections 250-146 and 250-148.

Note. The position of the ground of a receptacle is not specified in the NEC. The ground can be up, down, or sideways. Proposals to specify the mounting position of the ground were all rejected.

Tip #30 Isolated Ground Receptacles [210-7(c) FPN]

An insulated equipment grounding conductor is required for the isolated ground receptacle [250-146(d)], and a separate equipment grounding conductor must ground the metal box [250-148] and the metal cover plate [410-56(d)]. Isolated ground receptacles must be identified by an orange triangle located on the face of the receptacle [410-56(c)].

Tip #31 Receptacle Replacement [210-7(d)]

Where Grounding Means Exist. Where a grounding means exists in the receptacle enclosure, grounding-type receptacles shall replace nongrounding type receptacles and the receptacles grounding terminals must be grounded in accordance with Section 210-7(c).

GFCI Protection Required. When receptacles are replaced in locations where ground-fault circuit-interrupter protection is now required, the replacement receptacles must be GFCI protected. This includes the replacement of receptacles in bathrooms, garages, outdoors, crawl spaces, unfinished basements, kitchens, wet bar sinks and rooftops, etc.; see Section 210-8 for GFCI requirements.

Where No Ground Exists. Where no grounding means exist in the box, such as old NM cable without a ground, nongrounding-type receptacles can be replaced with:

·        A nongrounding type receptacle.

·        A GFCI-receptacle or a grounding type receptacle fed downstream from a GFCI-receptacle. These receptacles shall be marked “No Equipment Ground”.

·        A grounding-type receptacle protected with a GFCI circuit breaker. These receptacles shall be marked “GFCI Protected” and “No Equipment Ground”.

Note. The GFCI protection will function properly on a 2-wire circuit without an equipment grounding conductor. The equipment grounding conductor serves no purpose in the operation of the GFCI protection device and has no effect on the function of the GFCI test-button.

Tip #31 GFCI Protected Receptacles [210-8]

Ground Fault Circuit Interrupters are designed to protect persons from being injured or killed from an electric shock. Dangerous electric shock begins at about 10 – 30 milliampere and the GFCI protection device opens the circuit whenever ground-fault current exceeds 5 milliampere.

GFCI Protection (GFCI circuit breaker or GFCI receptacle) is required for all 125 volt, 15, and 20 ampere receptacles installed in the following dwelling unit locations:

(1) Bathroom Area

(2) Garage and Accessory Buildings

(3) Outdoor Receptacles

(4) Crawl Spaces

(5) Unfinished Basements

(6) Kitchen Countertop Surfaces

(7) Wet Bar Countertop Surfaces

Since 1971, the NEC has been expanding the requirements of GFCI protection to include the following locations:

NEC GFCI Protection
Area Section
Agricultural Building 547-9
Bathroom Receptacles  210-8(b)
Carnivals, Circuses and Fairs 525-18
Commercial Garages 511-10
Elevator Pits 620-85
Health Care Facilities 517-20(a), 517-21
Portable or Mobile Signs 600-10
Roof Top Receptacles 210-8(b)
Swimming Pools 680-6(a)
Temporary Wiring 305-6

Tip #32 Number of Branch Circuits [210-11]

General Lighting and Receptacles. The minimum number of general lighting and receptacle branch circuits for a dwelling unit shall be determined from the total connected load and the size or rating of the circuits used. See Example D1(a) in appendix D at the back of the National Electrical Code.

Question – Dwelling Unit. What is the minimum number of 15 ampere receptacle circuits required for general lighting and receptacles for a 2,100 square foot dwelling unit?

Answer. 4 circuits

Step 1. The general lighting and receptacle load is 3 VA per square foot.

            2,100 square feet x 3 VA = 6,300 VA

Step 2. Branch circuit requirement

            6,300 VA/120 volt = 52.5 ampere

Step 3. Number of 15 ampere circuits

            52.5 ampere/15 ampere = 4 circuits

Small Appliance Branch Circuits. Two or more 20 ampere appliance branch circuits are required for all receptacle outlets in the kitchen, dining room, breakfast room, pantry, or similar dining areas. Lighting outlets or other receptacle outlets cannot be connected to the small appliance branch circuit.

Note. Two small appliance circuits are not required for each separate countertop space.

Laundry Branch Circuit. One 20 ampere branch circuit is required for the laundry room receptacle outlet(s) [210-52(f)]. The laundry room receptacle circuit cannot serve any other outlet, such as the laundry room lighting or receptacles in other rooms.

The NEC does not require a separate circuit for the washing machine. Only a separate circuit for the laundry room receptacle(s) of which one can be for the washing machine and the others can be for convenience, Fig. 5-22.

Bathroom Branch Circuit. A 20 ampere circuit that does not supply any other load must supply the bathroom receptacle outlet(s) required in Section 210-52(d). According to UL, 125 volt, 15 ampere receptacles are rated for 20 ampere feed-thru and can be used for this purpose [210-21(b)(2)].

Note. This Section does not require a separate 20 ampere circuit for each bathroom. One 20 ampere circuit can be used to supply multiple bathroom receptacles.

Exception. A dedicated 20 ampere circuit to a single bathroom is permitted to supply the bathroom receptacle outlet(s) and other equipment within the same bathroom, but only if the equipment does not exceed 10 ampere (50 percent of the branch circuit ampere rating) in accordance with Section 210-23(a).

Tip #33 Arc-fault Circuit Interrupter (AFCI) Protection [210-12]

Effective January 1, 2002, all branch circuits that supply 125 volt, 15, and 20 ampere receptacles in dwelling unit bedrooms shall be AFCI protected.

An arc-fault circuit-interrupter is a device intended to provide protection from the effects of arcing faults by recognizing characteristics unique to arcing and by functioning to de-energize the circuit when an arc-fault is detected. An AFCI is designed to make a distinction between an unwanted, potentially damaging arc, and a condition necessary for continuation of power, such as the arc created when unplugging an appliance under load.

Note. Since the new requirement does not go into effect until “after the next Code cycle”, this issue is a moot point. However, the 1999 NEC does not prohibit the installation of AFCI devices before that date.

Tip #34 Conductor Sizing [210-19]

Continuous Loads. Branch circuit conductors for continuous loads must be sized no less than 125 percent of the continuous loads, plus 100 percent of the noncontinuous loads. Conductors are sized based on the ampacities as listed on Table 310-16 before any ampacity adjustment factors according to the terminal temperature rating as listed in Table 310-16. See Section 110-14(c) for terminal rating rules.

Note. Conductors shall have the ampacity (after any ampacity adjustment) to carry the load and the conductors shall have overcurrent protection in accordance with Section 210-20(a) and 240-3.

Question. What size branch circuit conductor is required for a 4-wire circuit supplying 44 ampere of nonlinear loads continuously? Terminals are rated for 75ºC, Fig. 5-24.

Answer. No. 6

Step 1. Circuit protection device size

            44 ampere load x 1.25 = 55 ampere [210-20(a)]

            60 ampere protection device [240-6(a)]

Step 2. Size conductor for continuous load

            44 ampere ´ 1.25 = 55 ampere

            No. 6 rated 65 ampere at 75ºC, Table 310-16

Step 3. Conductor must be rated 44 ampere

            75* ampere ´ 0.80 = 60 ampere

            * 90ºC ampacity Table 310-16, see 110-14(c)

Step 4. No. 6 conductor must have proper overcurrent protection, A 60 ampere protection device will protects a 60 ampere rated conductor [240-3].

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