Conduit drains

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cornbread

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Given the following: I'm in a chemical plant where the equipment motors / instruments are exposed the the weather. I have cable tray with tray rated cables running thru out the process, again exposed to the weather. I branch off the cable tray with conduit to a motor (approx. 30 ft). One engineer says I need to install a drain in the conduit and another engineer said I can leave the "tee" open as this will accomplish the same thing as the drain. The engineer that said to use drains cites NEC 501.15. The engineer that said not to use drains, considers the conduit run from the tray to the motor / instrument as part of the tray system and cites NEC 392.6.

Reason behind the debate is we have had problems using drains in this type of application. What say all you NEC guru's?
 
cornbread said:
Reason behind the debate is we have had problems using drains in this type of application. What say all you NEC guru's?
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I'd go with whichever will get you an engineer's seal or signature, so you can point and say "look at what it says here."
 
cornbread said:
Given the following: I'm in a chemical plant where the equipment motors / instruments are exposed the the weather. I have cable tray with tray rated cables running thru out the process, again exposed to the weather. I branch off the cable tray with conduit to a motor (approx. 30 ft). One engineer says I need to install a drain in the conduit and another engineer said I can leave the "tee" open as this will accomplish the same thing as the drain. The engineer that said to use drains cites NEC 501.15. The engineer that said not to use drains, considers the conduit run from the tray to the motor / instrument as part of the tray system and cites NEC 392.6.

Reason behind the debate is we have had problems using drains in this type of application. What say all you NEC guru's?
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Good question.

392.6 seems to differentiate between the raceway and the cable tray.
 
cornbread said:
Given the following: I'm in a chemical plant where the equipment motors / instruments are exposed the the weather. I have cable tray with tray rated cables running thru out the process, again exposed to the weather. I branch off the cable tray with conduit to a motor (approx. 30 ft). One engineer says I need to install a drain in the conduit and another engineer said I can leave the "tee" open as this will accomplish the same thing as the drain. The engineer that said to use drains cites NEC 501.15. The engineer that said not to use drains, considers the conduit run from the tray to the motor / instrument as part of the tray system and cites NEC 392.6.

Reason behind the debate is we have had problems using drains in this type of application. What say all you NEC guru's?
Click to expand...

1./ If you leave the conduit open where the cable enters the raceway then it is not a raceway, but a support for TC. In that case you can leave the T open since it is not a conduit system.

2./ If the cable enters into the conduit via a CGB, now you have a properly closed raceway - you may even strip the cable jacket from this point, but it is usually not practical - and the T should have an approved drain fitting on it.


The question in 1./ installation is where do you provide proper termination for the cable to transit from cable to single conductor. Since the motor termination enclosure is NEMA 3R/4 and it's rating integrity must be maintained. all openings and entries into that box should provide the same protection. Also the cable entering an enclosure must be secured at the point of entry to relieve stress from the conductor termination point.

IMO the best solution is to use -ER rated cable, use the conduit as a support, leqave the conduit open on both end and have a short drip-loop of TC-ER between the conduit and the motor JB and terminate the TC with a CGB. Use wire basket to route more than one cable and to save over conduit cost.
 
Does 110.12 (A) Unused openings..... force me in to using a drain fitting? Can one make the argument that the open leg of the TEE is used...used for a drain?
 
cornbread said:
Does 110.12 (A) Unused openings..... force me in to using a drain fitting? Can one make the argument that the open leg of the TEE is used...used for a drain?
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As I said earlier, use logic, but don't twist it. :D

The threaded openings on the fittings are designed - and tested for during the UL process - to facilitate entry into the condulet body by approved means and via approved devices. Conduit systems are designed to be closed systems. When you leave any opening 'unfinished' it flagged as a missing cover or open enrty point, regardless of reasoning.

If you decide to leave it open it can no longer be called a conduit or condulet, but a support system. Other parts of the support system and cabling would need to have a different installation method/features from the conduit installation to meet the NEC.
 
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At BASF.. I take it you folks use conduit drains in this type of application? Have you seen many failed drains?
 
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