NEC Questions and Answers based on 2017 NEC^® - November 2019

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For EC&M Magazine
By Mike Holt, NEC^® Consultant
Here's the follow-up to yesterday's newsletter. This includes the answers to the questions sent, so you can see how you did.

Note: The answers to these questions are based on the 2017 NEC.

Q1. What does the Code require for marking on hermetic refrigerant motor compressors and equipment?
A1. Multimotor and Combination-Load Equipment. Multimotor and combination-load equipment must have a visible nameplate marked with the manufacturer's name, rating in volts, number of phases, minimum conductor ampacity, and the maximum rating of the branch-circuit short-circuit and ground-fault protective device [440.4(B)].

Q2. What does the NEC require for equipment grounding and bonding of air conditioning and refrigeration equipment installed using a metal raceway that is run exposed on a roof?
A2. Where equipment is installed using a metal raceway is run exposed on a roof for air conditioning and refrigeration equipment, an equipment grounding conductor of the wire type must be installed within the outdoor portions of metal raceways that use non threaded fittings [440.9].Figure 01

Q3. What is the Code rule regarding the location of a disconnect for air-conditioning and refrigeration equipment?
A3. A disconnect for air-conditioning or refrigeration equipment must be located within sight from and readily accessible from the equipment [440.14].

Author's Comment:
• According to Article 100, Within Sight means that it's visible and not more than 50 ft from one to the other.

The disconnect can be mounted on or within the air-conditioning equipment, but it isn't permitted to be located on panels designed to allow access to the equipment, or where it will obscure the equipment nameplate.

Ex 1: A disconnecting means isn't required to be within sight from the equipment if the disconnect is lockable with provisions for locking to remain in place whether the lock is installed or not [110.25], and if the equipment is essential to an industrial process in a facility that has written safety procedures, and where the conditions of maintenance and supervision ensure only qualified persons service the equipment.

Ex 2: An accessible attachment plug and receptacle can serve as the disconnect.

Author's Comment:
• The receptacle for the attachment plug isn't required to be readily accessible.

Q4. What are the NEC branch circuit requirements for room air conditioners?
A4. Sizing Conductors and Protection. Branch-circuit conductors for a cord-and-plug-connected room air conditioner must have an ampacity not less than 125 percent of the rated-load current shown on the nameplate providing the unit rating doesn't exceed 40A, 250V single-phase [440.32, 440.62(A)].

Separate Circuit. If the room air conditioner is the only load on a circuit, the marked rating of the air conditioner must not exceed 80 percent of the rating of the circuit overcurrent protection device [440.62(B)].

Other Loads on Circuit. The total rating of a cord-and-plug-connected room air conditioner must not exceed 50 percent of the rating of a branch circuit where lighting outlets, other appliances, or general-use receptacles are also supplied [440.62(C)].

Q5. What does the Code require for the disconnecting means for a room air conditioner?
A5. An attachment plug and receptacle, or a flexible cord connector, can serve as the disconnecting means for a room air conditioner, if [440.63]:
(1) the manual controls on the room air conditioner are readily accessible and within 6 ft of the floor, or
(2) a readily accessible disconnect is within sight from the room air conditioner.