Bushings on Rigid

[Travel1100]

I am on a job that we are using rigid conduit into metal boxes. I have been told that we do not need bushings on the thread pipe unless it is 1-1/4 pipe in size. The only reference I could find that might allow that is the footnote for 344.46 that refers to nec 300.4 (f). I asume that the pipe size comes from the wire fill table that is the first size that you can install 3 #4 wires in a conduit. I think that the code is talking about a "substanstial fitting" and not just the throat insulators or fiber bushings.

If bushings are not required for 3/4rigid conduit than why are they made? I think the code requires the bushing on threaded RMC that enters a 4 x 4 metal box with a lock nut. Some clearification would be appreciated.

 

[walkerj]

Bushings are required for wire #4 and larger.

They are made that small so the manufacturers can pay off architects/engineers to spec them

 

[forman400b]

All cut & thread conduit shall have bushings, regardless of size:



344.46 Bushings.


Where a conduit enters a box, fitting, or other enclosure, a bushing shall be provided to protect the wire from abrasion unless the design of the box, fitting, or enclosure is such as to afford equivalent protection.

 

[aftershock]

I guess I can start using those 1/2" fiber bushings that have been collecting dust over the past years.

 

[realolman]

I'm with forman400. on RMC you need to use them on all sizes.

 

[LJSMITH1]

They are made that small so the manufacturers can pay off architects/engineers to spec them

Do you really believe that? :roll:

 

[dcspector]

Bushings are required for wire #4 and larger.

They are made that small so the manufacturers can pay off architects/engineers to spec them

Interesting. Look at 342.46 and 352.46...as far as bushings..It is all about protecting the conductors.