black pipe

Status
Not open for further replies.
M

mikey1489

New member
Is there something that I have missed. I have been told that there is 2 ways that black schedule 80 pipe can be used as conduit. I was always taught that this was not (NEVER) acceptable. I was told it was in 312 and was told it was in 318 in cases as a tray as long as it was threaded with nps and not npt. I have yet to find where this is aceptatable and what are the restrictions on it. I can not even see where it could be stretched to include it. can any one help me see what I missed?
 
Take a look at 344.6. This section requires that all rigid metal conduit, factory elbows and coupling and associated fittings be listed.

So unless black pipe is also listed as rigid metal conduit you could not use it as such.

The same requirement exists for intermediate metal conduit, see 342.6.

Chris
 
I don't buy it.

I have seen a fair number of electricians who substituted a gavlenized pipe elbow for a rigid conduit elbow though. Probably needed one and didn't have it on the truck so got one from the plumber.
 
When I was a factory electrician, we demo'd areas and reworked/retooled almost constantly. All the long pieces of conduit and plumbing pipe got reused where ever things got relocated to. It was dog-gone hard (sometimes impossible) to tell RMC apart from galvanized iron pipe when it was used and on a pipe cart all mixed up.
 
I run across this in old buildings that used to have gas lamps converted to electric lamps. What a great way to get the new wire to the electric lamp than run zip cord down the old gas pipe. At least thats the way I have seen it used. It drives me crazy to have to refeed some of these old lights and the customer wants to know why it took so long. It is usually not grounded either.
 
I seem to remember seeing somewhere that you could use black pipe as a chase for cables that did not need to be in conduit to meet code. The example I saw was a custom light pole with 12/3 SOWA from a JBOX in the base to the head on the top. Is this valid and if so, would this relate to the OP?
 
I believe the problem with using galvenized pipe or black pipe besides the differnce in the threads is that those pipes have a rougher weld on the inside, and electrical conduit has a slick coating on the inside that is less abrasive on the insulation of the conductors...
 
ultramegabob said:
I believe the problem with using galvenized pipe or black pipe besides the differnce in the threads is that those pipes have a rougher weld on the inside, and electrical conduit has a slick coating on the inside that is less abrasive on the insulation of the conductors...
Click to expand...
There is no difference in the threads between conduit and plumbing pipe.
 
don_resqcapt19 said:
There is no difference in the threads between conduit and plumbing pipe.
Click to expand...


isnt ridged conduit straight thread so you can run a locknut all the way up, and a plumbing pipe is taperd to cinch tite into plumbing fittings?
 
ultramegabob said:
isnt ridged conduit straight thread so you can run a locknut all the way up, and a plumbing pipe is taperd to cinch tite into plumbing fittings?
Click to expand...
Nope. Hubs and couplings are normally straight, however.
 
I'm not sure , but I think it's all tapered 3/4" per foot. I think that's what the npt stands for. (National Pipe Taper?)
I know you use the same dies for both conduit and pipe.
 
When I took my j-man's test back in the early seventies, one of the questions I missed was "What's the difference between galvanized plumbing pipe and rmc?" I remember it because I missed it.
Later that year I was taking an electrical course and asked the instructor the question. He said rmc is galvanized inside and out but plumbers pipe is only galvanized on the outside so we don't get galvanic poisoning from drinking water from them.
I don't know if he a=was right, but it sounded good.
 
DaveBowden said:
. . . I don't know if he was right, but it sounded good.
Click to expand...
I don't think he was right (I also don't know that he was wrong). I have always understood that electrical conduit was reamed so the conductors would not be damaged. I would like confirmation of this "fact" (old wives tale?) from someone who really knows. :-?
 
I to have heard that RMC has been "smoothed out" on the inside, but have been unable t find hard evidence. FWIW, according to Allied Pipe, their GRMC is coated outside and inside and the threads are also coated.
 
Status
Not open for further replies.
Top