wrapping rigid conduit

[mannyb]

Is it required to wrap rigid or IMC with wrap if it has contact with concrete? 344 does mention where protected by protection??

 

[petersonra]

Is it required to wrap rigid or IMC with wrap if it has contact with concrete? 344 does mention where protected by protection??

I don't see anywhere that it is "required". It is one way to protect the conduit from corrosion. I think a zinc coating would also be acceptable.

 

[tom baker]

At our Waste Water Treatment Plant, circa 1985, the RMC stubs out of the slab were badly corroded in 10 years..
I have used 3M pipe wrap, but one time looked at the instructions and it required a special primer.
For RMC I would wrap with 3M 70, half lapped, below and above the slab.
In an outdoor slab I would suggest a coated RMC.

 

[infinity]

Is it required to wrap rigid or IMC with wrap if it has contact with concrete? 344 does mention where protected by protection??

Short is no. Even old black pipe that was embedded 75 years ago is still around.

 

[winnie]

Of concern in some environments is the transition out of the concrete.

Conduit that is fully embedded in concrete is protected by a passivation layer in the alkaline environment.

Where the conduit exits the concrete you might have a focal point for corrosion.

-Jon

 

[don_resqcapt19]

My specs require a corrosion wrap at the concrete to earth interface, or concrete to air interface. From the UL Guide Information for "Rigid Ferrous Metal Conduit (DYIX)".

Galvanized rigid steel conduit installed in concrete does not require supplementary corrosion protection.
Galvanized rigid steel conduit installed in contact with soil does not generally require supplementary corrosion protection.
In the absence of specific local experience, soils producing severe corrosive effects are generally characterized by low resistivity (less than 2000 ohm-centimeters).
Wherever ferrous metal conduit runs directly from concrete encasement to soil burial, severe corrosive effects are likely to occur on the metal in contact with the soil.

 

[hillbilly1]

Back in the old days when I done new construction, nobody wrapped it, but recently I stopped by a job, and my foreman said the inspector wanted it wrapped, and he had been on some previous jobs elsewhere that required it. May be in the specs now, as Don mentioned he required it.