grounding bushings

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bhall1

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When do you have to use a grounding bushing?? Do you use one if the conduit does not contain an egc or the conduit was installed with reducing washers.
 
grounding bushings

The most common use, IMHO, is on service conduits when concentric or ecentric knockout as encuntered. See 250.92 for services and 250.97 for bonding over 250 to gr will give more specifics.
If there are no conecentric/eccentric knockouts, a grounding locknut migh suffice.
In general, grounding bushing are used to maintain an effective ground path when needed (around knockouts, etc.).
In regard to your specific question, you wouldn't necessarily need a gr bushing at reducing washers unless you were dealing with 250.92 or 250.97.
Secondly, and EGC in the conduit would not remove the need for a bushing to ground the conduit itslef.
 
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Is bonding conduit(with bushing) that is leaving a cable tray required, or would the U-bolt cover that?
 
i helped work on a portable comm. house for a cell tower that used a halo grounding system around the building and everything in the building had to be bonded using a rigid bonding bushing because of the sensetive of the electonics equipment used in the tower . that was the only time i have ever seen then used, where a degree of bonding had to be meet.
 
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