tapped copper bar on UL508A Cabinet

[WKI]

Hello, I work for a European machine manufacturer, and we have to build UL508A electrical cabinets.
I was wondering if it is possible to use tapped grounding bars for field connections. I am asking because the copper bar is not certified.
My idea was to include the tightening torque information in the electrical diagram.

Thanks in advance for your responses

 

[Jraef]

Technically, all components inside of a UL-508A panel must be listed for the purpose used. But personally, in my many years of building panels and going through UL inspections, none of the UL inspectors paid any attention to ground bus arrangements that we often fabricated ourselves. If it were power bus, absolutely, because it also involved temperature rises, fault bracing etc. But ground bars, meh.

 

[WKI]

Thank your for your reply.

In the UL508A standard I found the information below, it is noted that for grounding it is necessary to refer to section 28.
See point 28.2.3 below, but it doesn't say whether the components must be certified....

14.2 An industrial control panel shall be provided with a field wiring terminal for the connection of an
equipment grounding conductor. The terminal shall comply with:
a) The component requirements of a field wiring terminal in accordance with Section 28, Field
Wiring; or
b) The requirements in the Standard for Grounding and Bonding Equipment, UL 467.


28.2.3 A wire binding screw, other than one on a terminal block or a component, shall comply with the
following:
a) A terminal plate tapped for a wire-binding screw shall be of metal not less than 0.030 inch (0.76
mm) thick for a 14 AWG (2.1 mm2) or smaller wire, and not less than 0.050 inch (1.27 mm) thick for
a wire larger than 14 AWG (2.1 mm2). There shall be at least two full threads in the plate; and
Exception: Two full threads are not required if fewer threads result in a secure connection in which
the threads will not strip upon application of a 20 pound-inch (2.3 N·m) tightening torque.
b) A terminal plate formed from stock having the required thickness specified in (a) is able to have
the metal extruded at the tapped hole for the binding screw to provide two full threads; and
c) A wire-binding screw shall thread into metal; and
d) A wire-binding screw shall be No. 8 (4.2 mm diameter) or larger screw for securing a 10 AWG
(5.3 mm2) or smaller conductor, or a No. 6 (3.5 mm diameter) screw for securing a 14 AWG (2.1
mm2) conductor only.

 

[petersonra]

Technically, all components inside of a UL-508A panel must be listed for the purpose used. But personally, in my many years of building panels and going through UL inspections, none of the UL inspectors paid any attention to ground bus arrangements that we often fabricated ourselves. If it were power bus, absolutely, because it also involved temperature rises, fault bracing etc. But ground bars, meh.

There is no requirement that the metal meet any special requirements, just the termination itself. You can drill and tap a hole in the panel and screw the ground lug to that if you have two full threads of engagement and remove the paint under the lug.

 

[WKI]

Thank you for your expertise