NFPA79 11.4.3 ??

[milmat1]

NFPA79 11.4.3
"Subplates with area greater than 1.5484 m^2 requires additional support. Is this referring to a control panel backplate ?
What exactly is this telling us ?

 

[infinity]

Here's the definition of a Subplate from NFPA79 and the section you asked about.

3.3.99 Subplate. An internal metal surface separate from the walls of an enclosure or controller on which various component parts of the controller are mounted and wired.


11.4 Enclosures, Doors, and Openings.
11.4.1 Enclosures shall be constructed and finished using materials capable of withstanding the mechanical, electrical, and thermal stresses, as well as the effects of humidity and corrosion, that are likely to be encountered in normal service.
11.4.2 Where corrosion protection beyond normal requirements is needed, nonmetallic enclosures identified for the purposes shall be permitted if they meet the requirements of UL 508.
11.4.3 Subplates having a surface area of more than 15,484 cm2 (2400 in.2) shall have supports provided in addition to the panel mounting means to aid in subplate installation.

 

[petersonra]

NFPA79 11.4.3
"Subplates with area greater than 1.5484 m^2 requires additional support. Is this referring to a control panel backplate ?
What exactly is this telling us ?

Large sub panels usually come with brackets welded to the enclosure that the panel sits on. That way the weight is on the bottom of the box and not just the back wall