Teflon tape on RMC joints?

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kameele

kameele

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I was working on an upgrade bid at a gas metering station and noticed some existing conduit that was put together with Teflon tape on the joints. i had thought that this was specifically prohibited by the code, but cannot find any references where I thought they might be. obviously, this is prohibited if it makes the connection non-conductive, but I'd still like to know if there's a actual mention.

Thanks for any info.
 
I don't believe the Teflon will prevent metal-to-metal contact when the pipe is wrench-tightened. Teflon acts as a lubricant to allow deeper thread penetration, but it should squeeze out where the greatest contact-pressure points are.
 
You could always ask someone with a DLRO to make up a joint without and then with tape and compare the results. If I had one I'd try it.
 
kameele said:
I was working on an upgrade bid at a gas metering station and noticed some existing conduit that was put together with Teflon tape on the joints. i had thought that this was specifically prohibited by the code, but cannot find any references where I thought they might be. obviously, this is prohibited if it makes the connection non-conductive, but I'd still like to know if there's a actual mention.

Thanks for any info.
Click to expand...

You might be able to use 300.10 as a reference in the 2008 NEC. Note the words "effective electrical continuity"
 
300.6(A) mentions corrosion protection using "approved electrically conductive" compounds.
Teflon is not electrically conductive.
T&B Kopr-Shield could be used on the threads, but I don't think teflon tape is proper.
BUT - "APPROVED" indicates that, if the inspector approves it, you're ok.
As just a plain old Engineer - I would not approve it.

Years ago I had a summer job working for the gas company, and we put pipe dope on all the threaded joints. Maybe one of the pipe fitters was moonlighting as an electrican.
:smile:
db
 
kameele said:
I was working on an upgrade bid at a gas metering station and noticed some existing conduit that was put together with Teflon tape on the joints. i had thought that this was specifically prohibited by the code, but cannot find any references where I thought they might be. obviously, this is prohibited if it makes the connection non-conductive, but I'd still like to know if there's a actual mention.

Thanks for any info.
Click to expand...

As you working around gas, I presume that it is a classified area and as such at least some of it requires the conduit system to be XP rated. As the XP rating depends on the threaded joints relieving the gas pressure in case of internal explosion, the Teflon tape would interefere with that relieving capacity. This and the grounding continuity would be definite showstopper for me.

Just say no to drugs and Teflon on conduit threads and you'be fine....:D
 
barclayd said:
300.6(A) mentions corrosion protection using "approved electrically conductive" compounds.
Teflon is not electrically conductive.
T&B Kopr-Shield could be used on the threads, but I don't think teflon tape is proper.
BUT - "APPROVED" indicates that, if the inspector approves it, you're ok.
As just a plain old Engineer - I would not approve it.

Years ago I had a summer job working for the gas company, and we put pipe dope on all the threaded joints. Maybe one of the pipe fitters was moonlighting as an electrican.
:smile:
db
Click to expand...

Thank you all for your responses. I think this was the section I was thinking of. 300.10 is where I thought it would fall. I somehow doubt that Teflon tape is list for use on electrical fittings.
 
weressl said:
As you working around gas, I presume that it is a classified area and as such at least some of it requires the conduit system to be XP rated. As the XP rating depends on the threaded joints relieving the gas pressure in case of internal explosion, the Teflon tape would interefere with that relieving capacity. This and the grounding continuity would be definite showstopper for me.

Just say no to drugs and Teflon on conduit threads and you'be fine....:D
Click to expand...



Good catch, some forget in Classified locations how important the threaded connection is. That is the primary reason for 5 threads...allows for cooling of the fault/arc.
 
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