Bonding Bushings

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27hillcrest

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When is it reguired to install a bonding bushing? I have been on many job sites and have noticed locations I feel would require one when there is one. Any help with the NEC article would be great!
 
27hillcrest said:
When is it reguired to install a bonding bushing? I have been on many job sites and have noticed locations I feel would require one when there is one. Any help with the NEC article would be great!
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Give us some examples of when you think that they are required. Generally once you get past the service disconnect they are not required, except for some bonding over 250 volts.
 
always use a grounding bushing on all enclosures up to the first main. Example is: multiple enclosures at the service equipment and no main breaker in the first panel. Use on metallic raceways only, emt, rigid steel, etc. Regular Locknuts are not acceptable for grounding. Also use them on conduit runs when concentric/ecentric k.o.'s are in j.boxes, 480/277 runs. Install grounding conductor per Art. 250.122 The consept is to ensure that if the ungrounded conductor develops a fault, short, there is a good equip. gnd. without relying on those loose locknuts the "other guy" failed to tighten.
 
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Here is a location I assume that would need them a 225kva XFMR 480volt 208/120 being fed with a 4" flex 90 degree. The load side is 3 3" 90 degree flex connectors. Thanks,
 
27hillcrest said:
Here is a location I assume that would need them a 225kva XFMR 480volt 208/120 being fed with a 4" flex 90 degree. The load side is 3 3" 90 degree flex connectors. Thanks,
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Bonding bushing are not required on a transformer unless concentric, eccentric or tangential KO's are used on the over 250 volts conductors. Since I've never seen a 225KVA transformer with concentric, eccentric or tangential KO's, bonding bushing are really never required on a transformer.
 
Here is a location I assume that would need them a 225kva XFMR 480volt 208/120 being fed with a 4" flex 90 degree. The load side is 3 3" 90 degree flex connectors. Thanks,
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You don't need a bonding bushing, but you do need a bonding jumper around the flex.
Don
 
Alot of people use the Bond Bushings on X-Formers because it's easier to install than running a ground back across the flex to keep your bond thru the flex. You also have the issue of having to keep the wire from being damaged by other people working around the area.
Personally... I use 2 Bond bushings on the X-Frmr and the panel side just for good measure.
 
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