I discussed this matter with the UL representative of CMP 5 (Article 250). He was surprised as well, but looking at the listing standard, it appears as though under test conditions reducing washers that are listed are capable of carrying a tremendous amount of fault current. I don't recall the exat test now, but it was several thousand amps for a substantial duration.
Ryan Jackson, Salt Lake City
Re: Reducing Washers#95566 09/22/0510:45 AM09/22/0510:45 AM
I hate RE plates. I would rather screw a plate in the can and make sure there is a ground wire. I have had inspectors fail an installation; he wanted reducing washers; I had bolted a cover plate to the top of the box and had a grounding bushing and ground wire in the EMT. My way was better and I proved it to him with a megger. He made me change it to pass inspection. Still scratching my head Rod.