Insulated Throat EMT Connectors and 300.4(G)

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infinity

infinity

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Having a discussion recently as to whether or not an EMT connector with an insulated throat meets the intent of 300.4(G) (when used with conductors #4 and larger) in lieu of a plastic bushing. My opinion is that they are complaint because they meet the requirement of the last sentence because they are fastened in place.

300.4(G) Insulated Fittings. Where raceways contain 4 AWG or larger insulated circuit conductors, and these conductors enter a cabinet, a box, an enclosure, or a raceway, the conductors shall be protected by an identified fitting providing a smoothly rounded insulating surface, unless the conductors are separated from the fitting or raceway by identified insulating material that is securely fastened in place.
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TC722A-orig.jpg
 
infinity said:
Having a discussion recently as to whether or not an EMT connector with an insulated throat meets the intent of 300.4(G) (when used with conductors #4 and larger) in lieu of a plastic bushing. My opinion is that they are complaint because they meet the requirement of the last sentence because they are fastened in place.



TC722A-orig.jpg
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If I didn't know what a plastic bushing was, I'd say you just described the fitting in the picture.

JAP>
 
If I were an inspector, I'd let the fitting you pictured slide... but on a personal level I don't think they should be permitted to be compliant. I say this because there is no rounded throat on that fitting, and deeper into the fitting, the fitting metal is not separated from the conductors by the insulating throat.

Compare to rounding of this throat...

arlington-808a-emt-set-screw-connector-with-insulated-throat-1-pack-4-inch_17149300.jpeg
 
I would guess that the fitting in post #1 would keep the conductors from touching the actual fitting. The rounded insulating surface refers to an external bushing so I would see either of those pictured as being compliant.
 
The fitting insulation is rounded in post #1.
It just has a smaller radius that the fitting in post #2.
There is no requirement for the rounded radius.
 
tkb said:
The fitting insulation is rounded in post #1.
It just has a smaller radius that the fitting in post #2.
There is no requirement for the rounded radius.
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I think the rounding should at least be discernible by the naked eye... :happyyes:
 
GoldDigger said:
There is a very discernible rounding in the red plastic of the connector shown. Unfortunately that radiused part is on the outside of the indiscernibly rounded inner edge.
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By golly you are correct. :lol:

The section text is of no help. I inferred the rounded surface is to be the one the conductors make contact with. :slaphead:
 
infinity said:
Having a discussion recently as to whether or not an EMT connector with an insulated throat meets the intent of 300.4(G) (when used with conductors #4 and larger) in lieu of a plastic bushing. My opinion is that they are complaint because they meet the requirement of the last sentence because they are fastened in place.



TC722A-orig.jpg
Click to expand...

Compliant IMO also.
 
I've used these without an external plastic bushing on some larger EMT runs and found that the internal insulated throat didn't survive the rope and nose of the cable coming through it. Typically they popped right out and if you were lucky they didn't break and could be reinstalled. :roll:
 
infinity said:
I've used these without an external plastic bushing on some larger EMT runs and found that the internal insulated throat didn't survive the rope and nose of the cable coming through it. Typically they popped right out and if you were lucky they didn't break and could be reinstalled. :roll:
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Well, thank goodness for split ground bushings. That is, if avoiding repulling the wire saves half an hour or more for two guys it would be worth it.
 
I don't know that any plastic bushings is actually designed to survive the friction of a rope or conductors pulled across them with any resistance at all.
Its the installers job to keep this from happening when the wire starts to comes out of the raceway.

The plastic bushing is more to protect the conductor from the edge of the connector once the conductors are installed that may be sharply bent over the edge.

Wire guage smaller than #4 is more flexible and not as prone being damaged from the rounded edge of an uninsulated fitting.

But that's just my opinion.


JAP.
 
infinity said:
I've used these without an external plastic bushing on some larger EMT runs and found that the internal insulated throat didn't survive the rope and nose of the cable coming through it. Typically they popped right out and if you were lucky they didn't break and could be reinstalled. :roll:
Click to expand...

I agree they are compliant, but for the same reason you just mentioned, I always use a threaded bushing anyway where required.


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jaggedben said:
Well, thank goodness for split ground bushings. That is, if avoiding repulling the wire saves half an hour or more for two guys it would be worth it.
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We recently had an inspector question the use of those bushings and he implied that they were probably installed after the conductors were pulled in and therefore the condcutors may have possibly been damaged during the pull. :slaphead:
 
I always do but is there actually a requirement for a bushings to be installed prior to a pull?

JAP>
 
I used to have a set of steel bushing that got used during pulling so they wouldn't get destroyed. Then I changed them out for plastic once the wire pull was done.
 
Is there any where in the NEC where insulated throat or plastic bushings are required on smaller than #4 wire for branch circuit wiring?
I have an inspector giving me verbal correction that I need insulated throats on all my connectors, i.e. 4S boxes with #12 wire in 1/2" EMT.
I asked him for the code section but he just says it's in the code, I cant find anything.

Thanks
 
heybud said:
Is there any where in the NEC where insulated throat or plastic bushings are required on smaller than #4 wire for branch circuit wiring?
I have an inspector giving me verbal correction that I need insulated throats on all my connectors, i.e. 4S boxes with #12 wire in 1/2" EMT.
I asked him for the code section but he just says it's in the code, I cant find anything.

Thanks
Click to expand...

EMT connectors do not require bushings for conductors smaller than #4. He won't find a code section because he's incorrect.

305ecm31fig1.jpg
 
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