I recieved the following note on the use of conduit drains.
The NEC states that conduit systems shall be provided with an "approved means" to prevent accumulation of condensation and permit drainage of such liquid (Ref. Article 501 Class 1 Locations, Par. 501.15 Sealing and Drainage, (F) Drainage, (1) Control Equipment). In addition, the NEC Handbook provides an example of breather-drain fitting for this purpose. Based on this, I feel that drain fittings are required on conduits.
However,
The NEC also states that cable tray systems shall be permitted to have "mechanically discontinuous segments" between cable tray runs and equipment. The code permits wiring across the discontinuous segment up to 6 feet in length with proper support and guarding from physical damage. (Ref. Article 392 Cable Trays, Par. 392.6 Installation, (A) Complete System.)
Discussion/Interpretation:
The above articles actually address two types of wiring systems (ie; conduit and cable tray). In the plant, we can have 3 types of wiring systems; (1) a totally conduit system, (2) a totally cable tray system, and (3) a combination of conduit and cable tray. In totally conduit systems, standard individual building wire (ie: TW, THW, etc.) may be used. In cable tray systems, tray rated cable (ie: PLTC, TC, etc.) must be used. In a combination conduit and cable tray system, again, tray rated cable (ie: PLTC, TC, etc.) must be used.
In the case where totally conduit systems are installed with standard building wire, an approved drain or breather-drain fitting must be used. Standard building wire (ie, TW, THW, etc) is not rated or constructed for protection against physical damage, so the conduit system must protect it. Yes, even at the fitting.
In the case where tray rated cable is used in cable tray or combination conduit and cable tray systems, the code allows for mechanically discontinuous segments as long as 6 ft. Since tray rated cable has an additional jacket for physical protection, the wiring is protected over the discontinuous segment (3/4" hole). Based on this, I feel that any conduit systems using tray rated cable are in still in compliance without a drain fitting
I would appreciate your opinions.
The NEC states that conduit systems shall be provided with an "approved means" to prevent accumulation of condensation and permit drainage of such liquid (Ref. Article 501 Class 1 Locations, Par. 501.15 Sealing and Drainage, (F) Drainage, (1) Control Equipment). In addition, the NEC Handbook provides an example of breather-drain fitting for this purpose. Based on this, I feel that drain fittings are required on conduits.
However,
The NEC also states that cable tray systems shall be permitted to have "mechanically discontinuous segments" between cable tray runs and equipment. The code permits wiring across the discontinuous segment up to 6 feet in length with proper support and guarding from physical damage. (Ref. Article 392 Cable Trays, Par. 392.6 Installation, (A) Complete System.)
Discussion/Interpretation:
The above articles actually address two types of wiring systems (ie; conduit and cable tray). In the plant, we can have 3 types of wiring systems; (1) a totally conduit system, (2) a totally cable tray system, and (3) a combination of conduit and cable tray. In totally conduit systems, standard individual building wire (ie: TW, THW, etc.) may be used. In cable tray systems, tray rated cable (ie: PLTC, TC, etc.) must be used. In a combination conduit and cable tray system, again, tray rated cable (ie: PLTC, TC, etc.) must be used.
In the case where totally conduit systems are installed with standard building wire, an approved drain or breather-drain fitting must be used. Standard building wire (ie, TW, THW, etc) is not rated or constructed for protection against physical damage, so the conduit system must protect it. Yes, even at the fitting.
In the case where tray rated cable is used in cable tray or combination conduit and cable tray systems, the code allows for mechanically discontinuous segments as long as 6 ft. Since tray rated cable has an additional jacket for physical protection, the wiring is protected over the discontinuous segment (3/4" hole). Based on this, I feel that any conduit systems using tray rated cable are in still in compliance without a drain fitting
I would appreciate your opinions.