RMC and Teflon tape

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jwelectric

jwelectric

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North Carolina
Although this may sound a little silly I was wondering if anyone has an opinion on the use of threading compounds for Rigid Metal Conduit. Could Teflon Tape be used on the threads and the conduit still is the grounding path for fault current.
How about plumber?s joint compound for preventing leaks.
 
jwelectric said:
Although this may sound a little silly I was wondering if anyone has an opinion on the use of threading compounds for Rigid Metal Conduit. Could Teflon Tape be used on the threads and the conduit still is the grounding path for fault current.
How about plumber?s joint compound for preventing leaks.
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When I was working with AL rigid in a baby food plant, a non-toxic thread lube was required. I have never seen such a thing on steel RMC.

As for thread tape, I know it will insulate well. I spent years as a vehicle tech and people would put tape on sensors when they put them back in and sensors that used that connection for a ground wouldn't work.
 
If our conduit couplings did not have straight threads, I would say that there would be no real issue, but our couplings do have straight threads and the teflon tape or pipe dope may act as an insulator between the male and female threads. That being said, I have seen specs that required the use of plumbing pipe joint compound on the conduit threads. The only thing that I use now is something that meets the requirements of 300.6(A).

Plumbing pipe and fittings both have tapered threads. The purpose of the teflon tape or pipe dope is not to seal the joint, but rather to provide lubrication so that the joint can be tighened enough so that there is a metal on metal seal. The tape or dope does assist in the sealing by filling small imperfections in the threads.
 
don_resqcapt19 said:
If our conduit couplings did not have straight threads, I would say that there would be no real issue, but our couplings do have straight threads and the teflon tape or pipe dope may act as an insulator between the male and female threads. That being said, I have seen specs that required the use of plumbing pipe joint compound on the conduit threads. The only thing that I use now is something that meets the requirements of 300.6(A).

Plumbing pipe and fittings both have tapered threads. The purpose of the teflon tape or pipe dope is not to seal the joint, but rather to provide lubrication so that the joint can be tighened enough so that there is a metal on metal seal. The tape or dope does assist in the sealing by filling small imperfections in the threads.
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As I mentioned, tape will insulate. That may not be the intent, but I have seen it happen.

That being said, the method and material is moot. 300.10 requires electrical conductivity so whatever you do use, 300.10 has to be met.
 
don_resqcapt19 said:
The purpose of the teflon tape or pipe dope is not to seal the joint, but rather to provide lubrication so that the joint can be tighened enough so that there is a metal on metal seal. The tape or dope does assist in the sealing by filling small imperfections in the threads.
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This was the part I was seeking for, thanks. :)
 
K8MHZ said:
As I mentioned, tape will insulate. That may not be the intent, but I have seen it happen. ...
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I am sure it can happen, but it shouldn't happen when both the male and female threads are tapered. It is my opinion that it would be more likely to happen with conduit and conduit couplings, because the couplings are straight thread and not tapered thread like plumbing couplings.
 
don_resqcapt19 said:
I am sure it can happen, but it shouldn't happen when both the male and female threads are tapered. It is my opinion that it would be more likely to happen with conduit and conduit couplings, because the couplings are straight thread and not tapered thread like plumbing couplings.
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I saw it with tapered threads. It's not the threads, it's the person that wraps a half dozen wraps around the male part of the thread and then installs it.
 
don_resqcapt19 said:
The only other one that I know of is Crouse's STL.
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http://www.sanchem.com/aSpecialE.html
http://vendor.parker.com/Groups/Sea...1e00467ebc/$FILE/Compounds-Selector-Guide.pdf

...and many come in the form of an electrically-conductive anti-seize compound, such as:

http://www.permatex.com/products/au...ts/Permatex_Copper_Anti-Seize_Lubricant_b.htm

...and others:

https://www.google.com/webhp?source....,cf.osb&fp=62036adb3ec7aa61&biw=971&bih=1071

The compound does not have to be listed for the application. The key word in the requirement is the compound be approved.
 
Smart $ said:
... The compound does not have to be listed for the application. The key word in the requirement is the compound be approved.
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I don't think there is a listing for that type of product, but around here if it doesn't say something about use on electrical joints on the label, it won't be approved.
 
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