Seal-Tight Through Steel Jacket of A/C unit okay?

[drchcllc]

Does the NEC permit 3/4" seal-tight (FNM) conduit containing power via 8/2 + ground to pass through the steel jacket of an A/C condensing unit without the protection of a grommet? We're the installing HVAC outfit. The ST conduit is, of course, anchored at the local disconnect box and as it passes into the control box within the condensing unit, but passes bare as it enters the unit. Length of the conduit is less than 6'. Although the electrician has wired our units thusly for years, we finally came across an inspector who's raised his eyebrow at the practice. Hole is 1"1/8 and not tight to the ST.

 

[raider1]

How is the end of the sealtight flex terminated within the A/C unit?

The fact that the sealtight flex passes through a hole in a piece of metal is not a problem. For instance you can run sealtight flex through metal framing members without protection.

Chris

 

[mdshunk]

That sounds like how Rheem/Ruud set up their condensing units. It's kinda dumb. The sealtite goes through a big hole in the case of the unit, then termintates with a regular sealtite connector on the control box inside. I've serviced many of these that have been installed without the benefit of a grommet where the sealtite passes through the case, and have observed no visible damage among those I've seen.

 

[chris kennedy]

The fact that the sealtight flex passes through a hole in a piece of metal is not a problem. For instance you can run sealtight flex through metal framing members without protection.

Chris

Walls don't vibrate like an A/C unit.

 

[raider1]

Walls don't vibrate like an A/C unit.

Depends on where the walls are.

I am not advocating this as a good design, just that there is no code prohibiting LNFC from passing through a metal hole.

Chris

 

[Pierre C Belarge]

300.10, the last sentence
300.12
314.17(B)- last sentence
314.17(C)- last sentence


I do not see where any of these references would restrict the installation in the OP's post...as long as the raceway is secured to the enclosure inside the A/C unit.

 

[Cavie]

Does the NEC permit 3/4" seal-tight (FNM) conduit containing power via 8/2 + ground to pass through the steel jacket of an A/C condensing unit without the protection of a grommet? We're the installing HVAC outfit. The ST conduit is, of course, anchored at the local disconnect box and as it passes into the control box within the condensing unit, but passes bare as it enters the unit. Length of the conduit is less than 6'. Although the electrician has wired our units thusly for years, we finally came across an inspector who's raised his eyebrow at the practice. Hole is 1"1/8 and not tight to the ST.

8/2 + ground is a violation of wet location.

 

[wireman71]

Some sealtight has a metal internal jacket that would protect against any damage. There is some cheap, I think it's called Carlon, stuff that is just plastic. I personaly would use the stuff with the metal jacket inside it.

 

[mdshunk]

Some sealtight has a metal internal jacket that would protect against any damage. There is some cheap, I think it's called Carlon, stuff that is just plastic. I personaly would use the stuff with the metal jacket inside it.

That's two different classes of product.

Liquidtight Flexible Metallic Conduit (LTFMC), aka "SealTite"

Liquidtight Flexible Nonmetallic Conduit (LTFNMC), aka "Carflex"

Carflex is normally cheaper, but I find it a bit "sticky" to pull in. For whips and such, I often prefer to just push the conductors from point to point. This is sometimes frustrating with Carflex.