Shot in the dark...
Anybody know conclusively whether the back panel of a UL508A control panel can be used as EGC bus? Meaning, let's say you have a 3-terminal mechanical lug for incoming connections, and then need to also have 3-terminal mechanical lug for outgoing. Do you absolutely have to run a jumper between the two different lug sets, or is it good without the jumper because both lug sets are connected to the solid, single-piece back panel.
The language in 14.3 says "...by means of metal-to-metal contact or by means of an internal bonding conductor that complies with 15.2".
"metal to metal" seems to imply that this is ok.... but "metal to metal" seems way too broad and easy to attain (number of threads, etc), so it seems like it would be harder than that.
We usually just end up just playing it safe and running a jumper, but I don't like not knowing whether it is actually required or not.
Anybody know conclusively whether the back panel of a UL508A control panel can be used as EGC bus? Meaning, let's say you have a 3-terminal mechanical lug for incoming connections, and then need to also have 3-terminal mechanical lug for outgoing. Do you absolutely have to run a jumper between the two different lug sets, or is it good without the jumper because both lug sets are connected to the solid, single-piece back panel.
The language in 14.3 says "...by means of metal-to-metal contact or by means of an internal bonding conductor that complies with 15.2".
"metal to metal" seems to imply that this is ok.... but "metal to metal" seems way too broad and easy to attain (number of threads, etc), so it seems like it would be harder than that.
We usually just end up just playing it safe and running a jumper, but I don't like not knowing whether it is actually required or not.