I just read a post that reminded me of an ongoing dispute with a local AHJ that has yet to be fully resolved.
This is for a solar electric system. An inverter manufacturer we use has really crappy knockouts in their metal wiring boxes. So we end up installing metal reducing washers, on 3/4" knockouts for our 1/2" EMT (DC side) connections to the wiring box. (all knockouts have been removed)
The UL listing for metal reducing washers states "Metal reducing washers are considered suitable for grounding for use in circuits over and under 250 V and where installed in accordance with ANSI/NFPA 70, "National Electrical Code." Reducing washers are intended for use with metal enclosures having a minimum thickness of 0.053 in. for non-service conductors only. Reducing washers may be installed in enclosures provided with concentric or eccentric knockouts, only after all of the concentric and eccentric rings have been removed. However, those enclosures containing concentric and eccentric knockouts that have been Listed for bonding purposes may be used with reducing washers without all knockouts being removed."
This seems to tell me that ground bushing and jumper is NOT required because the metal reducing washer would meet sec. NEC 250.97 except 4.
The local AHJ is telling me they are required per NEC 250.97. Am I missing something? Would another code section apply?
Since it is just a ground bushing and jumper, I had one installed and past inspection. But I have followed up with the AHJ to get clarification, the last message I got simply stated that the AHJ would not be allowing metal reducing washers to be installed w/o a ground bushing and a jumper.
Can anyone shed some light on this of me?