rigid metal conduit

[joe]

A contractor at our facility is running 1" rigid conduit on our roof.While they are coupling this together they are using teflon tape at the threaded couplings.My question is are they following code?
I have never seen anyone before use anything like this.Does this have an effect on the bonding of the conduit?
Can someone show me what article in the NEC refers to this?I couldn't find anything in the rigid section or the grounding and bonding section.
By the way,these conduits are for security cameras.One conduit for power to the cameras and the other one is low voltage.

 

[pierre]

Re: rigid metal conduit

Joe

Are you sure these are not plumbers doing electrical work?
IMHO the teflon tape is a violation. The resistance built up by the tape will not allow fault current to flow, making the RMC a potential hazard.
250.96

Pierre

 

[hornetd]

Re: rigid metal conduit

If the couplings are made up wrench tight then the threads will cut through the tape to make an adequate connection.
--
Tom

 

[don_resqcapt19]

Re: rigid metal conduit

Is the use of teflon tape a violation of 250.12 or 250.96? What is the reason for using the tape? You may be required to use an electrically conductive, corrosion-resistant compound but 300.6. I don't think that teflon tape is electrically conductive.
Don

 

[flightline]

Re: rigid metal conduit

It's nice to say theat something is still before my time, but I believe that when they built some of the buildings at our facility, the threads were coated with "red lead". I do see most of the old pipe joints or exposed thread having this "orange" colored compound on them. I don't know of anyone today that uses the stuff anymore, perhaps due to the health risks.

When I have been faced with a situation where I wanted a "seal" as it were on the conduits, I have used Penetrox "E".

Here is an except from their website:

PEN_E-PT
PENETROX oxide-inhibiting compounds produce low initial contact resistance, seal out air and moisture, prevent oxidation or corrosion, exhibit superior weathering characteristics, are usable over wide temperature ranges, and provide a high conductivity "gas-tight" joint. All PENETROX compounds contain homogeneously suspended particles. The particles assist in penetrating thin oxide films, act as electrical "bridges" between conductor strands, aid in gripping conductor, improve electrical conductivity and enhance integrity of the connection. The specially formulated PENETROX compounds are for use with compression and bolted connectors providing an improved service life for both copper and aluminum connections. Additionally, the non toxic compounds are an excellent lubricant for threaded applications reducing galling and seizing.

I don't know if this is true for ALL of the Penetrox compounds, but it would appear that this one does.

I hope that this helps, Gregg.