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Article 409 provides the minimum safety requirements for industrial control panels ( What's an Industrial Control Panel? on page C12). Because this section of the Code is only a couple of pages long, it isn't that comprehensive. However, Table 409.3 lists more than two dozen other Articles that may apply to a given control panel, which definitely broadens its scope.
The NEC is primarily concerned with the hazards arising from the use of electricity, not the myriad of other issues that arise with industrial control panels. Thus, some things allowed by Art. 409 aren't optimal ( What Purpose Does it Serve? ). When there's a controls malfunction, the cause is unlikely to be an Art. 409 violation, unless the problem is of the "where's that smoke coming from?" variety.
Standards other than the NEC also apply to industrial control panels. Two that always apply are UL 508A, "Standard for Industrial Control Panels, and NFPA 79, "Electrical Standard for Industrial Machinery." NECA, NETA, and IEEE also have produced applicable standards for design, installation, testing, and/or maintenance. One more reference is critical. When industrial controls exhibit intermittent operation, a common cause is non-compliance with Art. 250 Part V (bonding). So make sure to build that compliance into your design and installation specs. Let's take a look at some specific guidelines.
Typing, sizing, and siting
Using Table 110.20, select the type of enclosure based on the intended environment. To determine the enclosure size, rough out its back planes, termination strips, and major component locations. Allow for enough space to install and wire these items with proper routing and bend radii.
An overlooked issue with larger control panels is the need to power test equipment and appliances, such as vacuums used for maintenance. Rather than ensure the need for extension cords, add sufficient receptacles at convenient locations, and allow for these in your rough layout. But don't place the order just yet. Work with your electrical distributor to see what standard offerings are closest to what you need. This collaboration can produce significant savings in cost and delivery.
If your panel is moderately complex, then you may have the option of "supplier engineering." Don't try to save money by not purchasing this. Have the supplier engineer the panel...