Air Tubing in electrical raceway

[bobgorno]

I have seen some old posts on this subject. 725.3 seem to allow you to ignore 300.8. It does seem Art. 100 definiton of raceways would apply however.

I haved an HVAC controls contractor who cites 725.3 as allowing him to run his plastic air tubing in rigid conduit with 24VAC signal wiring. My opinion differs from his.

Here's the kicker. There are explosion proof conduit boundary seals in this raceway. I believe he needs to separate the systems and remove the tubing from the XP seal.

 

[barbeer]

I would agree that he needs a separate raceway for his pneumatic control tubing. 300.8

 

[bobgorno]

Thanks. Is your opinion based on 300.8 or because of the XP seal?

 

[don_resqcapt19]

barbeer,
While in general 300.8 would prohibit the air tube in the conduit, that section does not apply where the conductors in the conduit are covered by Article 725. I am not sure how the fact that this conduit is in a classified area changes things. I am not sure that it does.
Don

 

[petersonra]

barbeer,
While in general 300.8 would prohibit the air tube in the conduit, that section does not apply where the conductors in the conduit are covered by Article 725. I am not sure how the fact that this conduit is in a classified area changes things. I am not sure that it does.
Don

Take a look at 500.3.

 

[bobgorno]

I've spent some time bouncing through the Code today and offer the following:

Many people have differing opinions of the statement in 725.3 that says only those sections in Article 300 that are specifically referenced shall apply. That would seem to allow us to ignore Article 300.8 which prohibits mixing of air and electrical in the same raceway.

725.3 does refer to 300.17, so 300.17 applies. 300.17 is number and size of conductors in a raceway. 300.17 refers to 342.22 and 344.22, Number of Conductors. These refer to Chapter 9. All articles and tables refer to conductors, conductor sizes, etc,. I see nothing in the NEC that defines conductors as anything but electrical or gives allowances for the sizing of air tubing fill in conduit

Article 100, defines Raceways. 725.3 does not exclude Article 100, so 100 applies. The definition of Raceway shows it as being expressly for wires, cables, busbars and other functions as permitted in the Code. Other functions permitted in the Code are its use for grounding and where specifically allowed, as a support. Nowhere is the function of a raceway specifically allowed to include the mixing air with electrical.

Article 725.54 says Class 2 circuits shall be installed in accordance with 725.55 thru 725.58. Nowhere in these articles does it say Class 2 wiring can be installed in the same raceway with air or other systems.

Article 725.3 says installations must comply with Articles 500 thru 516. For this installation 500 and 501 apply. Nowhere in these articles is air tubing allowed to share a raceway or conduit seal. Article 500.3 says all other applicable rules in this Code shall apply except as modified in 500-504. So, 300.8 applies.

Article 500.3 trumps all. The air tube must be removed. I'm not sure that being in an unclassified area would matter based on 725.54.

 

[petersonra]

Article 725.54 says Class 2 circuits shall be installed in accordance with 725.55 thru 725.58. Nowhere in these articles does it say Class 2 wiring can be installed in the same raceway with air or other systems.
...
I'm not sure that being in an unclassified area would matter based on 725.54.

If it is not forbidden, it is allowed.

Take a look at 725 .61D too.