dmulhol925
Member
Where does the NEC require using two lock nuts, 1 inside, 1 outside on rigid conduit?
Lock Nuts
- Thread starter dmulhol925
- Start date
- Status
Ohms law
Senior Member
- Location
- Sioux Falls,SD
This is coming from the 2014 NEC book, if you look in the glossary under (Locknuts,double, required), you will find a list of references.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
I don't think it is ever actually required.
It is one installation option of several.
It is one installation option of several.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
It is also required in hazardous areas and mobile homes--550.15(F). I will add that I have never seen RMC run without a locknut on both sides unless a threadless connector was used.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
I have. It is a violation, but some people will use a locknut and a metal bushing.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Well you say it is a violation but I have not seen an article other than the few mentioned that requires 2 locknuts. I thought it was a violation but I don't see the art.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
The violation is using a bushing where a locknut is required. The bushing is not listed as a fitting to secure the RMC.
http://www.emersonindustrial.com/en...tting/conduit-bush-rmc-imc/Pages/default.aspx
Is that more clear as to what I was trying to say?
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I can't imagine why a locknut is only required on one side. Just does not seem right. :thumbsdown:
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
It would depend whether there is a fitting, such as the threadless connector you mentioned earlier, or some other fitting is used I suppose.
As I think of it, a coupling and a chase nipple would not use a locknut at all, silly install, but could be compliant.
In don't read it that way. Unless otherwise specified a metal bushing on the inside and a locknut on the outside of the enclosure is an acceptable means.
I discussed it with a UL rep and he is in agreement. To me, the wording on the referenced Appleton cut sheet can indicate a locknut on the outside and a metal bushing on the inside.
We my end up agreeing to disagree.
I discussed it with a UL rep and he is in agreement. To me, the wording on the referenced Appleton cut sheet can indicate a locknut on the outside and a metal bushing on the inside.
We my end up agreeing to disagree.
kwired
Electron manager
- Location
- NE Nebraska
Until the conductors are 4AWG or larger, then the bushing must be "insulating" according to 300.4(G).
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
True but that is not what Gus is addressing. Besides you could have a metal bushing with an insulated throat
kwired
Electron manager
- Location
- NE Nebraska
I think it is what is addressed. A metal bushing can be on inside of enclosure and locknut on outside to secure the raceway to the enclosure, then we have 300.4(G) to comply with on top of securing the raceway. I did not quote the entire section, but yes a metal bushing with insulated throat should fulfill the requirements of that section.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I understand that but the insulated throat or bushing was not what this thread is about. That is all I am saying. You just added another dimension to the question.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
So now the question is why is a locknut needed on the rmc with the bushing but not the locknut.
kwired
Electron manager
- Location
- NE Nebraska
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Yes what the heck is that---:lol:
Why is a locknut not needed on the outside for RMC but it is required with the bushing
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
That never happens here
Yes it does but when you quoted Gus it seems like you are trying to correct him. Maybe I just read it that way- no biggie.
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