bonding with reducing washers

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SceneryDriver

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Electrical and Automation Designer
I seem to be missing the part of 250 that clearly states that if one end of an EMT conduit run (feeder, not service conductors) is in a field-punched, non-concentric KO, it's OK to use reducing washers on the other end of the conduit run without the use of a bonding bushing.

For reference:
-120/240V single phase feeder
-Reducing washers on the "supply end" of the conduit run
-Ground wire (sized for the feeder) pulled in and landed in the non-concentric KO's enclosure.

Ironically, the concentric is still in place, but we used reducing washers because the concentric KO on the Square D fused switches are terrible and very weak. I'm being told we need a bonding bushing at reducing washers end.

I've seen the handy flowchart that floats around on this forum, but the version I have doesn't cite code sections and I can't find the above. I really wish it was made clearer and easier to grasp.



SceneryDriver
 
UL Listing QCRV states the following:
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,’’ for raceways containing other than service conductors. Reducing washers are intended for use with metal enclosures having a minimum thickness of 0.053 in. 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 certified for bonding purposes may be used with reducing washers without all knockouts being removed.
 
Devil's advocate:
250.97 Exception 4 indicates bonding per 250.92 is not required for "Listed Fittings"/
IF reducing washers are listed and installed per Post #2, would and additional bonding be requiired on circuits > 250 volts ??
 
But regardless of the reducing washers, the fact that the other end of the conduit run terminates in a enclosure with a field-punched 2" KO (no reducing washers), and that enclosure is properly bonded with a wire-type EGC negates the whole reducing washers discussion, yes?


SceneryDriver
 
SceneryDriver said:
But regardless of the reducing washers, the fact that the other end of the conduit run terminates in a enclosure with a field-punched 2" KO (no reducing washers), and that enclosure is properly bonded with a wire-type EGC negates the whole reducing washers discussion, yes?


SceneryDriver
Click to expand...
IMO, yes
 
Absent other language on the matter, one can infer from the requirement in 250.64(E)(1) to bond a GEC to both ends of a metal raceway containing it that a double-ended bonding requirement is the exception, rather that the general rule.

Cheers, Wayne
 
electrofelon said:
Not really, it's more that the code just says it has to be bonded, and doesn't say it needs to be bonded twice or on both ends
Click to expand...
Get this - he's now saying that I need bonding bushings because even though they're feeder conductors they originate in the service disconnect, so that makes them service conductors according to him. I just can't with this guy any more.


SceneryDriver
 
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