Code Change Summary: Revised code section now permits energy management devices inside overcurrent device enclosures.

In the 2017 NEC^®, Section 312.8(B) only addressed power monitoring equipment installed inside overcurrent device enclosures such as cabinets or cutout boxes. It’s very common to see power monitoring equipment installed in panelboard cabinets and the intent of this section is to ensure that the presence of power monitoring equipment inside an enclosure doesn’t create an overcrowding issue or violate any product certifications.

In the 2020 NEC^®, a public input (code change proposal) was accepted to also include energy management equipment in this section. To monitor power consumption is one thing, to manage or control the power usage is altogether different and yet both power monitoring and energy management equipment is currently available for purchase.

If installing power monitoring or energy management equipment inside a switch enclosure or other overcurrent device enclosure, the power monitoring or energy management equipment must be identified as a field installable accessory as part of a listed equipment, or must be a listed kit, evaluated for field installation in switch or overcurrent device enclosures. As well, the total area of all conductors, splices, taps, and equipment at any cross section of the wiring space cannot exceed 75 percent of the cross-sectional area of that space.

New line item 3 was added to address instrumentation and control circuits for such devices which are often between 18 AWG and 22 AWG conductors. This new section provides two options for these instrumentation or control circuits:

• Install only a specific type of insulated conductor as a class 1 circuit in accordance with the rules in Section 725.49.

OR

• Conductors smaller than 18 AWG, but not smaller than 22 AWG for a single conductor, and 26 AWG for a multiconductor cable, can be installed if all of the following conditions are met:
  • Conductors must be enclosed within raceways or routed along one or more walls of the enclosure and secured at intervals that do not exceed 10 inches.
  • Conductors must be secured within 10 inches of terminations.
  • Conductors must be secured to prevent contact with current carrying components within the enclosure.
  • Conductors must be rated for the system voltage and not less than 600 volts.
  • Conductors must have a minimum insulation temperature rating of 90°C.

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 2020 NEC^® edition of NFPA 70.