# EMT Busing???



## Dude Man (Dec 15, 2008)

I went back to work on Monday. We are running parallel 3" EMT for 600Amp Panels out of the service. In our pull boxes and any other terminating point we have the 3" EMT Compression type Insulating Throat Connectors. I thought you have to but a Bushing on. The guy I am working with says no. Looking at 

*300.4(G)*
(G) Insulated Fittings. Where raceways contain 4 AWG
or larger insulated circuit conductors and these conductors enter a cabinet, box, enclosure, or raceway, the conductors shall be protected by a substantial fitting providing a smoothly rounded insulating surface, unless the conductors are separated from the fitting or raceway by substantial insulating material that is securely fastened in place.

Exception: Where threaded hubs or bosses that are an integral part of a cabinet, box, enclosure, or raceway provide a smoothly rounded or flared entry for conductors.

Conduit bushings constructed wholly of insulating material shall not be used to secure a fitting or raceway. The insulating fitting or insulating material shall have a temperature rating not less than the insulation temperature rating of the installed conductors.

So now I am thinking he is right. However my next question arrives at: substantial insulating material that is securely fastened in place. The connectors we have have this insulating insert stuck it won't move. So I think we don't need bushings. I have seen the ones that the insulating part is loose, a person can spin around inside the connector and sometimes the fall out. So would you need in on this type of connector?

In the back of my mind I think the plastic bushings are cheap for a little added security when pulling in large conductors, even with insulated throat.

Thanks for any input.


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## Thayer (Sep 22, 2008)

I believe that you came to the correct conclusion. I have always interpreted that an additional bushing is not required to be used. With this said, I always add an additional thread on bushing just for increased safety:thumbsup:.


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## Dude Man (Dec 15, 2008)

Ooops, I see the typo in my title. Supposed to be bushing not busing. I would change it but I don't know how.


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## nick (Feb 14, 2008)

Dude Man said:


> Ooops, I see the typo in my title. Supposed to be bushing not busing. I would change it but I don't know how.



Well its ok i never could spell myself , ya we kinda do lots of feeder stuff on projects power distibution large feeders . http://i611.photobucket.com/albums/tt195/stringking/P1010009_02.jpg
Heres what we due if the connector is insulated throat then we do not add or install a plastic bushing , 

If we install flex connectors in a transformer we always use bonding bushings on transformer side even if its a insulated throat each with a pass thur lug .

If we install a connector in a concentric ko we install a bonding bushing .

If we have unprotected feeders meaning a parallel group of secondarys out of a transformer or a group of feeders out of a generator unprotected its bonding bushings and grounded . 

If we wire up a motor its a bonding bushing .

If in vibrates or moves its a bonding bushing .

If its a vertical riser we use wire support bushings for that size wire .

If its just pvc and not rigid or emt stubs we use pvc bells for protection of conductors . 

we agree anything larger than no. 4 awg and 3/4 pipe or larger it needsl protection meaning plastic bushings or bonding bushings . Take care


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## william1978 (Sep 21, 2008)

If it has an insulated throat in the connector than you don't need a plastic bushing.


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## leland (Dec 28, 2007)

Dude Man said:


> Ooops, I see the typo in my title. Supposed to be bushing not busing. I would change it but I don't know how.



Good catch. Busing didn't work too well here.:whistling2:


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## Pierre Belarge (Feb 3, 2007)

nick said:


> Well its ok i never could spell myself , ya we kinda do lots of feeder stuff on projects power distibution large feeders . http://i611.photobucket.com/albums/tt195/stringking/P1010009_02.jpg
> Heres what we due if the connector is insulated throat then we do not add or install a plastic bushing ,


 

I am curious, what are the different bare conductors that enter the 2 different sections of the gear?


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## william1978 (Sep 21, 2008)

Pierre Belarge said:


> I am curious, what are the different bare conductors that enter the 2 different sections of the gear?


 I'm thinking water pipe, building steel, ground rods thats just what I think.


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## nick (Feb 14, 2008)

Pierre Belarge said:


> I am curious, what are the different bare conductors that enter the 2 different sections of the gear?


Well its a bare ground which runs on top of the duck bank of that section each switch board has a group of conduits that run underground to other parts of the project they have a 3/0 bare thats one foot above top of duck bank and runs the length of duck bank . 

We install building steel, ground rods, uffer ground, cold water and lighting protection counter posie ground , to the main GROUND BAR located in main electrical room this also goes to the section one of the main gear .

When the duck bank hits the other side it goes to a ground bar in that new remote sub electrical room .

Each 50 foot run of duck bank out side building slab has a ground rod sunk and all rods cadwelded to the attached 3/0 bare conductor as engineer specs and drawns details show this is on most of our projects one line grounding plans lots of fun . Take care


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