Insulating bushings

Status
Not open for further replies.
S

SceneryDriver

Senior Member
Location
NJ
Occupation
Electrical and Automation Designer
I use the screw-on insulating bushings such as these:

http://yblighting.com/media/catalog...f78eab33525d08d6e5fb8d27136e95/8/3/831_21.jpg

whenever I have to use GRS nipples to connect enclosures, and I'm in the habit of using them on larger runs of EMT that terminate in enclosures. I tend to use them when the conduit is filled to near max, or when the conductors might be raked over an edge due to the geometry of a wire pull.

Is there a hard and fast rule of where their use is required? It makes sense to use them on rigid nipples, as there can be sharp edges, but is it really necessary to use them everywhere? I've never seen them used when a 1/2" conduit enters a 4-square box, for instance.



SceneryDriver
 
Thank you. I knew there was a code reference, but I couldn't find it.



SceneryDriver
 
SceneryDriver said:
I use the screw-on insulating bushings such as these:

http://yblighting.com/media/catalog...f78eab33525d08d6e5fb8d27136e95/8/3/831_21.jpg

whenever I have to use GRS nipples to connect enclosures, and I'm in the habit of using them on larger runs of EMT that terminate in enclosures. I tend to use them when the conduit is filled to near max, or when the conductors might be raked over an edge due to the geometry of a wire pull.

Is there a hard and fast rule of where their use is required? It makes sense to use them on rigid nipples, as there can be sharp edges, but is it really necessary to use them everywhere? I've never seen them used when a 1/2" conduit enters a 4-square box, for instance.



SceneryDriver
Click to expand...

There is no hard & fast rule other than 300.4(g) as stated by jumper. Let your personal experience & work habits guide you. So in the past five years how many nicked wires have you encountered due to pulling over connectors ?

When a person turns 100 years old newscasters are likely to ask "What habit has led to your long life ?" The response is likely "Eating turnip soup & a shot of whiskey daily? or some other equally ridiculous response. Which brings up the question How long would they have lived had they not eaten turnip soup ?
Let your personal experience & work habits guide you !!
 
John120/240 said:
There is no hard & fast rule other than 300.4(g) as stated by jumper. Let your personal experience & work habits guide you. So in the past five years how many nicked wires have you encountered due to pulling over connectors ?

When a person turns 100 years old newscasters are likely to ask "What habit has led to your long life ?" The response is likely "Eating turnip soup & a shot of whiskey daily? or some other equally ridiculous response. Which brings up the question How long would they have lived had they not eaten turnip soup ?
Let your personal experience & work habits guide you !!
Click to expand...

I think jumpers reference to 3XX.46, such as 342.46 is pretty hard and fast.
 
This graphic from Mike may help:

300-04F-UN300-13-CO8.jpg
 
Reading 352.46 I do not see it as clear as others do. Although I do not use bushing, I see it as the fittings such as slip fittings, hubs and boxes with hubs are exempt from bushings. I don't see how a standard connector would add adequate protection. There is also no reason for this article if no bushing is needed other than to refer to 330.4(G)
 
It took me a minute to grasp Mike's graphic, but I think it's right on target.
That said, go to your local supply house and see how much dust is on top of the 1/2" & 3/4" box of plastic bushings. :)
 
At least the supply house has bushings to get dust on them. I went the other day to get some of the white plastic bang on bushings for EMT. Nah, we dont have those and the main office in Knoxville doesnt keep them either. Whaaaaat? Lol.
 
augie47 said:
It took me a minute to grasp Mike's graphic, but I think it's right on target.
That said, go to your local supply house and see how much dust is on top of the 1/2" & 3/4" box of plastic bushings. :)
Click to expand...
maybe not as much dust as you might think, I've see them used a lot in places they are not required
 
Status
Not open for further replies.
Top