Is it a NEC code violation to paint PVC

[kwired]

EMT does fine in many environments as long as physical abuse isn't too severe. The key to success is installation practices not so much the product itself.

Use of low grade die cast fittings may be more subject to breaking then a good steel fitting. Proper securing and supporting comes into play as well. Rusted out tubing? Usually because of failure to arrange the system to drain. Failure to arrange to drain does allow the tube to fill with water and in areas that get cold results in that water freezing and splitting the tubing open. This can happen with RMC/IMC though not as easily.

 

[Carultch]

EMT does fine in many environments as long as physical abuse isn't too severe. The key to success is installation practices not so much the product itself.

Use of low grade die cast fittings may be more subject to breaking then a good steel fitting. Proper securing and supporting comes into play as well. Rusted out tubing? Usually because of failure to arrange the system to drain. Failure to arrange to drain does allow the tube to fill with water and in areas that get cold results in that water freezing and splitting the tubing open. This can happen with RMC/IMC though not as easily.

Die cast vs steel is a tradeoff. Die cast isn't as strong as steel, but the coating on the steel is only zinc plated. Not galvanized. The zinc plated steel corrodes in typical outdoor environments. Die cast zinc will not corrode nearly as much as zinc plated steel, but as mentioned, it isn't as mechanically robust as steel.

 

[Fulthrotl]

I know it is prudent to confirm everything with JHA, however does painting PVC violate 110.3 (B) Installation and Use, or 110.21(A) Marking: Manufacturers Marking as referenced in 352.120 Marking? The conduit is not going underground. The example would be running PVC exterior on a roof associated with a Photovoltaic system. I guess I am answering my own question but I suppose PVC can be painted if the manufacturers mark can still be observed....?

the truth is, PVC degrades in direct sunlight, and painting it helps prevent that.

as for the inspector needing to see it, he probably will be mostly interested in
the schedule of the pipe. anyone stepping on 2" PVC will not mistake it for GRC,
and are not likely to mistake sch. 40 or sch. A for schedule 80.

ASK the ahj before you paint. anyone who has ever put in telephone backboards
without leaving the fireproof marking visible will never do it a second time. i'd
approach this the same way.

 

[Carultch]

the truth is, PVC degrades in direct sunlight, and painting it helps prevent that.

as for the inspector needing to see it, he probably will be mostly interested in
the schedule of the pipe. anyone stepping on 2" PVC will not mistake it for GRC,
and are not likely to mistake sch. 40 or sch. A for schedule 80.

ASK the ahj before you paint. anyone who has ever put in telephone backboards
without leaving the fireproof marking visible will never do it a second time. i'd
approach this the same way.

Why is it acceptable for a product to be listed and marked as sunlight resistant or UV stable, if it still degrades in sunlight?

 

[mgookin]

Why is it acceptable for a product to be listed and marked as sunlight resistant or UV stable, if it still degrades in sunlight?

Sunlight resistant does not mean sunlightproof.


UV inhibitor is added to the mix when they make CPVC. It is more sunlight resistant than PVC which does not contain the inhibitor.

 

[mgookin]

Stumbled on this today, from Carlon:
How to paint a PVC raceway:
http://www.carlonsales.com/techinfo/installationtraining/IT-PVC_Conduit_Painting.pdf

 

[gadfly56]

Sunlight resistant does not mean sunlightproof.


UV inhibitor is added to the mix when they make CPVC. It is more sunlight resistant than PVC which does not contain the inhibitor.

Very true. The same stick of PVC might last 50 years on a roof in Scotland but only 3-5 years in Arizona.

 

[jaggedben]

Very true. The same stick of PVC might last 50 years on a roof in Scotland but only 3-5 years in Arizona.

Or 50 years on the east or west wall of a house, but only 3-5 years on the roof.

 

[pv_n00b]

A lot of things that are labeled sunlight resistant get that label through a 700 hour UV lamp test. So they will not break down for a few years under average conditions. But then again even when the PVC starts to breakdown it's not like the sunlight is able to instantly penetrate the full depth of the wall. It's going to start to breakdown on the surface and as long as that UV damaged material stays around it slows further damage. So it's a few years before visible damage shows but many more years before serious structural compromise occurs. I've run across some pretty old PVC conduit on roofs in Hawaii that looks pretty bad but structurally is still hanging in there.

For small plastic items like cable ties where there is much less material and it is generally under stress a complete UV breakdown can take only a few years.

 

[ggunn]

A lot of things that are labeled sunlight resistant get that label through a 700 hour UV lamp test. So they will not break down for a few years under average conditions. But then again even when the PVC starts to breakdown it's not like the sunlight is able to instantly penetrate the full depth of the wall. It's going to start to breakdown on the surface and as long as that UV damaged material stays around it slows further damage. So it's a few years before visible damage shows but many more years before serious structural compromise occurs. I've run across some pretty old PVC conduit on roofs in Hawaii that looks pretty bad but structurally is still hanging in there.

For small plastic items like cable ties where there is much less material and it is generally under stress a complete UV breakdown can take only a few years.

Nevertheless, I will not be using PVC conduit on rooftops. With PV systems being warrantied for 20 years I don't trust it to last that long.