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Joined: Jan 2004
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Does anyone have any information on the use of reducing washers?
George Little
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UL White Book OUTLET BUSHINGS AND FITTINGS (QCRV) GROUNDING 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.’’ That's all I have except they make big holes small.
Bob Badger Construction & Maintenance Electrician Massachusetts
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Thanks Bob- That's what I needed.
George Little
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That information really makes me question the technical expertise of UL. Don
Don(resqcapt19)
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Don I think the problem is the difference between test conditions and real life.
I have no doubt you or I could make reducing washers carry fault current if we used a wire brush to remove all paint from the enclosure and tightened the lock nuts decently.
However I know I see reducing washers all the time that are up against paint and loose.
I think an inspector could cite 250.12 Clean Surfaces almost every time.
Personally I dislike everything about reducing washers.
Bob Badger Construction & Maintenance Electrician Massachusetts
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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
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I'm sorry, but if the test conditions do not represent a real world installation, the results are worthless. Don
Don(resqcapt19)
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I vote with Bob. Reducing washers keep the connector from falling out but I would use a bonding nut if I wanted to make a secure grounding connection.
Greg Fretwell
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Joined: Jun 2004
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Reducers -- gotta hate 'em....
Every time I see them it's a hack job.
I particularly dislike reducers used at NEMA3R disconnects where the installer is shrinking back from a 1 inch KO goof.
Tesla
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Joined: Jan 2005
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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.
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