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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.
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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 MC cable can be used and installed?
A1: 330.10 Uses Permitted
(A) General Uses. Type MC cable can be used:
(1) For branch circuits, feeders, and services.
(2) For power, lighting, control, and signaling circuits.
(3) For indoor or outdoor locations.
(4) Exposed or concealed.
(5) To be directly buried (if identified for the purpose).
(6) In a cable tray.
(7) In a raceway.
(8) As aerial cable on a messenger.
(9) In hazardous (classified) locations as permitted in 501.10(B), 502.10(B), and 503.10.
(10) Embedded in plaster or brick in dry locations.
(11) In wet locations, where a corrosion-resistant jacket is provided over the metallic sheath and any of the following conditions are met:
a. The metallic covering is impervious to moisture.
b. A jacket is provided under the metal covering that is moisture resistant. Figure 01
(B) Specific Uses.
(1) Cable Tray. Type MC cable can be installed in a cable tray in accordance with Article 392.
(2) Direct Buried. Direct-buried cables must be protected in accordance with 300.5.
(3) Installed as Service-Entrance Cable. Type MC cable is permitted to be used as service-entrance cable when installed in accordance with 230.43.
(4) Installed Outside Buildings. Type MC cable installed outside buildings must comply with 225.10, 396.10, and 396.12.
Note: The “Uses Permitted” is not an all-inclusive list, which indicates other suitable uses are permitted if approved by the authority having jurisdiction.
Q2: Under what conditions can MC cable not be used and installed?
A2: 330.12 Uses Not Permitted
Type MC cable is not permitted to be used where:
(1) Subject to physical damage.
(2) Exposed to the destructive corrosive conditions in (a) or (b), unless the metallic sheath or armor is resistant to the conditions or protected by material resistant to the conditions:
a. Direct burial in the earth or embedded in concrete unless identified for the application.
b. Exposed to cinder fills, strong chlorides, caustic alkalis, or vapors of chlorine or hydrochloric acids.
Q3: What are the NEC requirements for installing MC cable for exposed work?
A3: 330.15 Exposed Work
Exposed runs of Type MC cable, except as provided in 300.11(B), must closely follow the surface of the building finish or running boards. Type MC cable installed on the bottom of floor or ceiling joists must be secured at every joist and not be subject to physical damage.
Q4: What are the NEC requirements for installing MC cable through or parallel to framing members?
A4: 330.17 Through or Parallel to Framing Members
Type MC cable installed through or parallel to framing members or furring strips must be protected against physical damage from the penetration of screws or nails by maintaining a 1¼ in. separation, or by installing a suitable metal plate in accordance with 300.4(A), (C), and (D).
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