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For EC&M Magazine
By Mike Holt, NEC® Consultant
Here's the follow-up to yesterday's newsletter.
This includes the answers to the questions sent, so you can see how you did.
Figure 01
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Figure 01
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For EC&M Magazine
By Mike Holt, NEC® Consultant
Here's the follow-up to yesterday's newsletter.
This includes the answers to the questions sent, so you can see how you did.
Note: The answers to these questions are based on the 2020 NEC.
Q1: What are the conditions wireways can be used and installed?
A1: 376.10 Uses Permitted
Wireways are permitted to be used in the following manners:
(1) Exposed.
(2) In any hazardous (classified) locations as permitted by other articles in the Code.
(3) In wet locations where listed for the purpose.
(4) Unbroken through walls, partitions, and floors.
Q2: Under what conditions can wireways not be used and installed?
A2: 376.12 Uses Not Permitted
Wireways are not permitted to be used:
(1) Where subject to severe physical damage.
(2) Where subject to corrosive environments.
Q3: What are the NEC requirements for installing conductors in parallel inside wireways?
A3: 376.20 Conductors Connected in Parallel
Where conductors are installed in parallel as permitted in 310.10(G), the parallel conductors must be installed in groups consisting of not more than one conductor per phase or neutral conductor to prevent current imbalance in the paralleled conductors due to inductive reactance. Figure 01 Note: The purpose of having all parallel conductor sets within the same group is to prevent current imbalance in the paralleled conductors due to inductive reactance.
Q4: What is the NEC requirement for cables and conductor transitioning from a cable tray to a raceway?
A4: 392.46 Bushed Conduit and Tubing
A box is not required where cables or conductors are installed in a bushed raceway used for support, protection against physical damage, or where conductors or cables transition to a raceway from the cable tray.
(A) Through Bushed Conduit or Tubing. Individual conductors or multiconductor cables with entirely nonmetallic sheaths, can enter enclosures where they are terminated through nonflexible bushed conduit or tubing installed for their protection, provided they are secured at the point of transition from the cable tray and the raceway is sealed at the outer end using an approved means so debris is prevented debris from entering the equipment through the raceway.
(B) Flanged Connections. Individual conductors or multiconductor cables with entirely nonmetallic sheaths can enter enclosures through openings associated with flanges from cable trays where the cable tray is attached to the flange and the flange is mounted directly to the equipment. The openings must be made so the conductors are protected from abrasion and must be sealed or covered to prevent debris from entering the enclosure through them.
Note: One method of preventing debris from entering the enclosure is to seal the outer end of the raceway or the opening with duct seal.
Q5: What is the NEC requirement for splicing cables and conductors installed in cable trays?
A5: 392.56 Cable Splices
Splices are permitted in a cable tray if the splice is accessible and insulated by a method approved by the authority having jurisdiction. Splices can project above the side rails of the cable tray if not subject to physical damage.
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