Bonding bushing requirements. Anyone able to correct or complete my checklist?

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Carultch

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Here's my bonding bushing requirement checklist. Anyone want to add to it?


You need a bonding bushing if:
1. Your raceway contains service conductors.
2. Your raceway contains grounding electrode conductors. In fact, you may need one on both ends, for GEC performance. Is there a practical "short length" below which standard conduit bonding practices are acceptable in this application?
3. Your raceway terminates on non-metallic enclosures
4. Your raceway terminates on ring knockouts remaining, and the circuit exceeds 250 V to ground nominal
5. Your raceway does not terminate on an enclosure.

You do not need a bonding bushing if:
1. Your raceway is non-metallic.
2. The other end of your raceway terminates on another enclosure with proper electrical continuity to the raceway. Except where needed for GEC performance.
3. You use alternative fittings, such as a bonding locknut, a bonding Myers hub, with a screw to connect the EGC. Or other listed bonding fittings, which can receive a jumper.
4. In any of the above examples, a standard plastic bushing is an acceptable alternative
 
As you've noted for #1 in paragraph 1 there are other means to bond service raceways besides bonding bushings.
There are bonding hubs that can be used with GEC's.
 
infinity said:
As you've noted for #1 in paragraph 1 there are other means to bond service raceways besides bonding bushings.
There are bonding hubs that can be used with GEC's.
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I guess what I'm trying to say, is have I missed any applications where standard locknuts are insufficient for electrical continuity?
 
In #3, paragraph 1, if your raceway is metallic and contains an EGC would you still need the bonding bushing or is that covered by #2 in paragraph 2?
 
infinity said:
In #3, paragraph 1, if your raceway is metallic and contains an EGC would you still need the bonding bushing or is that covered by #2 in paragraph 2?
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That's my understanding. If your conduit has an EGC, you only need to bond one end of it. And if one end is already bonded to a bonded enclosure via a standard locknuts getting proper continuity, then there is no need for anything more substantial.
 
Carultch said:
That's my understanding. If your conduit has an EGC, you only need to bond one end of it. And if one end is already bonded to a bonded enclosure via a standard locknuts getting proper continuity, then there is no need for anything more substantial.
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I agree but there are some here who disagree.
 
6. Class I Div 2 grounding when using non explosion proof equipment. And other hazardous locations.

7. For SSBJ in SDS with EMT or RMC. :D

To specify for #4 - all boxes up to 100 cu in are evaluated for bonding circuits more than 250V. Cabinets are not.

My personal opinion - required when reducing donuts are used.
 
Or fact that one may think that enclosure of xfmr rattles thus the extra bushing. But it's the core that buzzez not the enclosure.


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don_resqcapt19 said:
The .30(A) sections in 501, 502 and 503.
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To add to Don's list, it also applies to x.25(A) in Articles 505 and 506 for Zone classified locations. It even applies to "unclassified" wiring methods where Article 504 is used. See Section 504.60. For reasons I can only partially explain, CMP14 is paranoid about bonding.
 
Carultch said:
You do not need a bonding bushing if:

2. The other end of your raceway terminates on another enclosure with proper electrical continuity to the raceway. Except where needed for GEC performance.
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Not trying to come up with convoluted ways to add find fault with your list ;), I have run into times where a bonding bushing is required on both ends of a raceway containing service conductors. Consider meter -> EMT -> trough -> PVC to service disconnect. Installer elects to NOT bond the neutral to the trough in the trough which is reasonable due to the hassle of it. He/she could install a bonding bushing at each end of the EMT with jumper to meter and trough.
 
electrofelon said:
Not trying to come up with convoluted ways to add find fault with your list ;), I have run into times where a bonding bushing is required on both ends of a raceway containing service conductors. Consider meter -> EMT -> trough -> PVC to service disconnect. Installer elects to NOT bond the neutral to the trough in the trough which is reasonable due to the hassle of it. He/she could install a bonding bushing at each end of the EMT with jumper to meter and trough.
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IMO the NEC requires the neutral to be directly bonded to the trough in that example.
 
Flex said:
#3. I have a question on. Can someone explain the purpose of this please? Also which code section
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Which #3? The one about nonmetallic enclosures, or the one about alternative bonding fittings?

Suppose you are running metal conduit from a fiberglass box to another fiberglass box. For obvious reasons, it isn't possible to bond it to the box via standard locknuts or standard Myers hubs. And any piece of metal that doesn't intentionally carry current needs to be bonded to ground. Metal conduit included. Therefore, if you run metal conduit from fiberglass to fiberglass, you need to run a separate jumper from the ground busbar to the conduit.

If by contrast, you run from a fiberglass box to a standard no-knockout metal box, then bonding the conduit to the already bonded metal box is sufficient. Even if the other side terminates on a fiberglass box.
 
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