408.18(C) Connections.
Code Change Summary: New code section requires manufacturer marking to identify when equipment requires side or rear access for terminals.
The new code language in 408.18(C) is for manufacturers, and the intent is to let the service electrician know which sections of equipment contains terminals for field connections. The new code language requires the manufacturer to provide a label on the front of the equipment that identifies any side or rear access needed to make field connections.
There are many switchboard or switchgear configurations where the only way to make terminations in the field is to have access to the sides or rear of the equipment (see image). Working space is required for the sides and rear of any such electrical equipment if it might be examined or worked on while energized.
Simply having a disclaimer in the installation instructions regarding the possibility of rear access is not enough. The manufacturer is now required to have a marking on the front of the equipment if rear or side access is required. This ensures that the installing electrician will see the label and provide proper working space on the side or behind the equipment when it is initially installed. Realizing this after the equipment is installed is way too late.
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.
2017 Code Language:
This code section did not exist.
2020 Code Language:
N 408.18(C) Connections. Each section of equipment that requires rear or side access to make field connections shall be so marked by the manufacturer on the front. Section openings requiring rear or side access shall comply with 110.26. Load terminals for field wiring shall comply with 408.18(C)(1), (C)(2), or (C)(3) as applicable.
N (1) Equipment Grounding Conductors. Load terminals for field wiring shall be so located that it is not necessary to reach across uninsulated ungrounded bus in order to make connections.
N (2) Grounded Circuit Conductors. Where multiple branch or feeder grounded circuit conductor load terminals for field wiring are grouped together in one location, they shall be so located that it is not necessary to reach across uninsulated ungrounded bus, whether or not energized, in order to make connections.
Where only one branch or feeder set of load terminals for field wiring are grouped with its associated ungrounded load terminals, they shall be so located that it is not necessary to reach across energized uninsulated bus including other branch or feeder bus in order to make connections. Bus on the line side of service, branch, or feeder disconnects is considered energized with respect to its associated load side circuits.
N (3) Ungrounded Conductors. Load terminals for ungrounded conductors shall be so located that it is not necessary to reach across energized uninsulated bus in order to make connections. Bus on the line side of service, branch, or feeder disconnects is considered energized with respect to its associated load side circuits.