Last edit: 27/01/2024
On 9th January 2024 the new edition of Industrial Machinery NFPA 79, the electrical standard for industrial machineries in the USA, was published. That will be valid for the next three years.
Here the main changes compared with the 2021 Edition.
- Industrial Control Panel Nameplate: SCCR
- With the new edition of January 2024, it will be clarified that, in case of electrical equipment consisting of multiple panels, the main panel can have 2 SCCR values:
- The first referred to the SCCR of the panel itself, according to UL 508A
- The second referred to the SCCR of the whole Electric equipment, according to NFPA 79
- The second SCCR value (whole electrical equipment) can therefore be less than the first (main panel).
[NFPA 79: 2024] A.16.4.1(6) The short-circuit current rating of the industrial control panel of the machine might include additional industrial control panels supplied from the industrial control panel containing the machine supply circuit disconnecting means. The short-circuit current rating of the industrial control panel of the machine as marked on the nameplate considers the short-circuit current ratings of these additional industrial control panels.
2. Supply Circuit Disconnecting Means
- With the new edition of January 2024 it is confirmed that next to each main disconnecting device there must be the following indications
[NFPA 79: 2024] 5.1 Machine Supply Circuit and Disconnecting Means. 5.1.1 Machine Supply Circuit.
5.1.9.2 Each machine supply circuit disconnecting means shall be legibly marked as Machine Supply Circuit and Disconnecting Means on or adjacent to the device and indicate the equipment it disconnects.
3. Opening of the control panel (Basic protection)
- We remind that, from the 2021 edition of NFPA 79, it is no longer required that the opening of the doors of a control panel be linked to the absence of voltage (NFPA 79 = UL 508A)
- Moreover, with the new January 2024 edition, IPxxB is recognized as sufficient protection against the risk of direct contact (basic protection).
- Therefore, in the case of a Control panel, that can be opened without the use of a key, the interior can simply be IPxxB rather than completely protected from contacts with active parts.
4. Colour of Conductors
- With the new January 2024 edition of NFPA 79 it is required that the DC circuits that remain live when the general disconnector is open are orange with blue stripes
