By Mike Holt for EC&M Magazine
Here’s the follow up to yesterday’s newsletter. This includes all of the answers to the questions sent, so you can see how you did.

Q1. When installing recessed luminaires, what Code rules must be followed?
A1. Recessed incandescent luminaires must be identified as thermally protected [410.115].

Author’s Comment: When higher-wattage lamps or improper trims are installed, the lampholder contained in a recessed luminaire can overheat, activating the thermal overcurrent device and causing the luminaire to cycle on and off.

• A recessed luminaire that isn’t identified for contact with insulation must have all recessed parts, except the points of supports, spaced not less than 1⁄4 in. from combustible materials.
• A Type IC luminaire (identified for contact with insulation) can be in contact with combustible materials.

Thermal insulation must not be installed above a recessed luminaire or within 3 in. of the luminaries’ enclosure, wiring compartment, or ballast, transformer, LED driver, or power supply unless identified for contact with insulation, Type IC.

Fixture wires installed in accordance with Article 402 and protected against overcurrent in accordance with 240.5(B)(2), are permitted to run from the luminaire to an outlet box located at least 1 ft away from the luminaire, as long as the conductors aren’t over 6 ft long [410.117].

Q2. What is the Code rule regarding disconnecting means for fluorescent luminaires?
A2.  In indoor locations, other than dwellings and associated accessory structures, fluorescent luminaires that utilize double-ended lamps (typical fluorescent lamps) and contain ballasts that can be serviced in place must have a disconnecting means [410.130(G)(1)].

For existing installed luminaires, a disconnecting means must be added at the time a ballast is replaced.

Author’s Comment: Changing the ballast while the circuit feeding the luminaire is energized has become a regular practice because a local disconnect isn’t available.

Ex 2: A disconnecting means isn’t required for the emergency illumination required in 700.16.

Ex 3: For cord-and-plug-connected luminaires, an accessible separable connector, or an accessible plug and receptacle, is permitted to serve as the disconnecting means.

Ex 4: A disconnecting means isn’t required in industrial establishments with restricted public access where written procedures and conditions of maintenance and supervision ensure that only qualified persons will service the installation.

Ex 5: If more than one luminaire is installed and is supplied by a branch circuit that isn’t of the multiwire type, a disconnecting means isn’t required for every luminaire; but, only when the light switch for the space ensures that some of the luminaires in the space will still provide illumination.

When connected to multiwire branch circuits, the fluorescent luminaire disconnect must simultaneously break all circuit conductors of the ballast, including the neutral conductor [410.130(G)(2)].

Author’s Comment: This rule requires the disconnecting means to open “all circuit conductors of a multiwire branch circuit,” including the neutral conductor. If the neutral conductor in a multiwire circuit isn’t disconnected at the same time as the ungrounded conductors, a false sense of security can result in an unexpected shock from the neutral conductor.

The fluorescent luminaire disconnecting means must be accessible to qualified persons, and if the disconnecting means is external to the luminaire, it must be a single device and must be located in sight from the luminaire [410.130(G)(3)].

Q3. What does the Code require in regard to the identification and termination of a “wild leg” in a panelboard?
A3. Panelboards supplied by a 4-wire, delta-connected, three-phase (high-leg) system must have the high-leg conductor (which operates at 208V to ground) terminate to the “B” phase of the panelboard [408.3(E)].

Ex: The high-leg conductor can terminate to the “C” phase when the meter is located in the same section of a switchboard or panelboard.

Note: Orange identification, or some other effective means, is required for the high-leg conductor [110.15 and 230.56].

Warning: The ANSI standard for meter equipment requires the high-leg conductor (208V to neutral) to terminate on the “C” (right) phase of the meter socket enclosure. This is because the demand meter needs 120V and it gets it from the “B” phase.

WARNING: When replacing equipment in existing facilities that contain a high-leg conductor, use care to ensure that the high-leg conductor is replaced in the original location. Prior to 1975, the high-leg conductor was required to terminate on the “C” phase of panelboards and switchboards. Failure to re-terminate the high leg in accordance with the existing installation can result in 120V circuits being inadvertently connected to the 208V high leg, with disastrous results.

Q4. Does the NEC include a minimum and maximum height for switches or circuit breakers?
A4.  Switches and circuit breakers used as switches must be capable of being operated from a readily accessible location. They must also be installed so the center of the grip of the operating handle of the switch or circuit breaker, when in its highest position, isn’t more than 6 ft 7 in. above the floor or working platform [240.24(A) and 404.8(A)].

Author’s Comment: The disconnecting means for a mobile home must be installed so the bottom of the enclosure isn’t less than 2 ft above the finished grade or working platform [550.32(F)].

Ex 1: On busways, fusible switches and circuit breakers can be located at the same level as the busway where suitable means is provided to operate the handle of the device from the floor.

Ex 2: Switches and circuit breakers used as switches can be mounted above 6 ft 7 in. if they’re next to the equipment they supply, and are accessible by portable means [240.24(A)(4)].

Q5.  Does the Code allow range hoods to be cord-and-plug connected?
A5. Range hoods can be cord-and-plug-connected if all of the following conditions are met [422.16(B)(4)]:

• The flexible cord terminates with a grounding-type attachment plug.
• The length of the cord must not be less than 18 in. or longer than 36 in.
• The range hood receptacle must be located to avoid physical damage to the flexible cord.
• The range hood receptacle must be accessible.
• The range hood receptacle must be supplied by an individual branch circuit.

Author’s Comment: An above the range microwave that contains a fan listed as a range hood must comply with this section, if it’s cord-and-plug-connected.

For more NEC Practice, purchase Mike Holt's NEC Exam Practice Questions book based on the 2011 NEC.