300.4(F)

Status
Not open for further replies.

ryan_618

Senior Member
(F) Insulated Fittings. Where raceways containing delete "ungrounded"ungrounded conductors 4 AWG or larger 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.


Change to read:


(F) Insulated Fittings. Where raceways containing conductors 4 AWG or larger 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.


Substantiation:

As written, this important protection requirement does not apply to the grounded conductor. The grounded conductor, in many cases, is every bit as dangerous as the ungrounded conductor. This is especially true when multi-wire circuits are employed. Isolated phase installations permitted by 300.3(B)(1) are an example of where this could apply.

[ May 11, 2005, 09:55 PM: Message edited by: ryan_618 ]
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
Re: 300.4(F)

Looks good, one thought:

Originally posted by ryan_618:
...the conductors shall be protected by a substantial fitting providing a smoothly rounded insulating surface...
What does substantial mean? Have you seen a bushing with no substance? :)
 

charlie

Senior Member
Location
Indianapolis
Re: 300.4(F)

George, how about solidly built; strong for a definition. That is straight out of the dictionary which is what is supposed to be used if the definition is not in the Code. In other words, I don't feel like it is a nebulous statement. :D
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Re: 300.4(F)

I would add the words "or cables" after raceways. The same problem exists with cable connectors as with raceway terminations.
Don
 
Status
Not open for further replies.
Top