Code Change Summary: Section 422.12 was expanded to permit additional associated equipment, including germicidal irradiation luminaires, service receptacles, and required lighting outlets, to be connected to the individual branch circuit supplying central heating equipment.

SME commentary: The 2026 NEC^® revises Section 422.12 to broaden the list of equipment permitted to share the individual branch circuit supplying central heating equipment. Previously, exception 1 only permitted auxiliary equipment such as pumps, valves, humidifiers, or electrostatic air cleaners directly associated with heating equipment on this circuit. The revision was prompted by a public input requesting that germicidal irradiation luminaires, which are commonly installed within the plenum of a central heating system, be recognized as permissible connected loads in exception 1. These fixtures are designed to disinfect air as it circulates through the system and are typically low-current devices that present negligible impact on circuit loading.

During the public input process, it was noted that these luminaires may already be permitted in exception 1 under the umbrella of “auxiliary equipment” but without solid code language it may be open to interpretation. The code panel acknowledged that requiring a separate branch circuit for such low-current devices would serve little practical or safety purpose. To address this and avoid having to repeatedly expand the list in future cycles, Exception No. 1 to 422.12 was modified to include the term “similar equipment”. Now, “auxiliary equipment, such as pumps, valves, humidifiers, electrostatic air cleaners, and similar equipment directly associated with the heating equipment, shall be permitted to be connected to the same branch circuit as the central heating equipment. This language provides flexibility for additional associated components, such as germicidal irradiation luminaires, to be connected to the same branch circuit when their electrical characteristics and association with the heating system justify doing so.

Additionally, exception 2 was expanded to allow the receptacle outlet required by 210.63(A) and the lighting outlet required by 210.70(C) to be supplied from the individual branch circuit required by the parent text for the central heating equipment. These receptacles and lighting outlets are typically installed in attics, crawl spaces, or mechanical rooms where central heating equipment is located. The inclusion of these outlets on the same individual branch circuit is both practical and safe since the combined load of the heating equipment, service receptacle, and lighting outlet would not typically overburden the circuit.

The revised language in Section 422.12 reflects an effort by the NEC^® to balance electrical safety with functional design efficiency. By adding the phrase “similar equipment,” the Code now accommodates modern auxiliary components that directly support heating systems without forcing installers to install unnecessary additional circuits. The inclusion of service and lighting outlets under exception 2 simplifies installations while maintaining compliance with required accessibility and servicing provisions. These updates make the rule more adaptable to current HVAC practices and emerging technologies, ensuring that low-current associated equipment, including germicidal irradiation luminaires, can safely operate on the same circuit as central heating systems.

Below is a preview of the NEC^®. See the actual NEC^® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2026 NEC^® edition of NFPA 70.

2023 Code Language:

422.12 Central Heating Equipment. Central heating equipment other than fixed electric space-heating equipment shall be supplied by an individual branch circuit.

Exception No. 1: Auxiliary equipment, such as a pump, valve, humidifier, or electrostatic air cleaner directly associated with the heating equipment, shall be permitted to be connected to the same branch circuit.

Exception No. 2: Permanently connected air-conditioning equipment shall be permitted to be connected to the same branch circuit.

2026 Code Language:

422.12 Central Heating Equipment. Central heating equipment other than fixed electric space-heating equipment shall be supplied by an individual branch circuit.

Exception No. 1: Auxiliary equipment, such as pumps, valves, humidifiers, electrostatic air cleaners, and similar equipment directly associated with the heating equipment, shall be permitted to be connected to the same branch circuit.

Exception No. 2: Permanently connected air-conditioning equipment, receptacles required by 210.63(A), and lighting outlets required by 210.70(C) shall be permitted to be connected to the same branch circuit.