Plumbing pipe used as electrical conduit?

Tainted

Senior Member
Location
New York
Occupation
Engineer (PE)
There is weird looking piping above an electrical wireway as shown in picture below. I am not sure if this is plumbing piping. Is plumbing piping allowed to be used as an electrical conduit?

1715018882614.png
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
Black iron electrical conduit was a thing a long time ago, but basically people stopped using it post WWII, because galvanizing (as an offshoot of military developments) became too cheap and easy to not just go that route for everything, so conduit suppliers only had to make and inventory one product.

So you can no longer buy black iron electrical conduit now, but you could have in the 1920s and 30s, which is likely what you are looking at here.
But NO, you cannot use "plumbing pipe" as electrical conduit. As mentioned, the plumbing pipe standards are different in terms of the inner surfaces so as to not damage wire insulation. So the material starts out the same, but conduit is given a few extra steps in the manufacturing process that plumbing pipe doesn't require.
 

Tainted

Senior Member
Location
New York
Occupation
Engineer (PE)
Black iron electrical conduit was a thing a long time ago, but basically people stopped using it post WWII, because galvanizing (as an offshoot of military developments) became too cheap and easy to not just go that route for everything, so conduit suppliers only had to make and inventory one product.

So you can no longer buy black iron electrical conduit now, but you could have in the 1920s and 30s, which is likely what you are looking at here.
Got it, I'm also assuming there is nothing in the code that says you can't use conduit that is not recognized by the NEC?
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Got it, I'm also assuming there is nothing in the code that says you can't use conduit that is not recognized by the NEC?
344.6 requires that conduit being installed be listed. All of the listed rigid metal conduit is galvanized, so you can't install black enamel protected rigid metal conduit in a new installation.
There is nothing that prohibits the use or reuse of black enamel protected RMC that was installed when that was hot rigid conduit was protected.
300.6(A)(1) even addresses enamel protected raceways.
(1) Protected from Corrosion Solely by Enamel.
Where protected from corrosion solely by enamel, ferrous metal raceways, cable trays, cablebus, auxiliary gutters, cable armor, boxes, cable sheathing, cabinets, enclosures (other than surrounding fences and walls), elbows, couplings, nipples, fittings, supports, and support hardware shall not be used outdoors or in wet locations as described in 300.6(D).
 

nizak

Senior Member
Must have been a glue as you go type install.

You might be able to pull a couple #14’s thru the 4” elbows☹️
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
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