370.10 and 370.12 Cablebus. Uses Permitted, Uses Not Permitted.

Cablebus is an assembly of sections with insulated conductors forming a structural system used to securely support conductors in a protective metal housing. The assembly is designed to carry fault current and to withstand the magnetic forces of such current.
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Cablebus is an assembly of sections with insulated conductors forming a structural system used to securely support conductors in a protective metal housing. The assembly is designed to carry fault current and to withstand the magnetic forces of such current.

Code Change Summary: The applications where cablebus can be used has been restructured to align with the NEC® format used in other articles.

According to 370.2, cablebus is “an assembly of units or sections with insulated conductors having associated fittings forming a structural system used to securely fasten or support conductors and conductor terminations in a completely enclosed, ventilated, protective metal housing. This assembly is designed to carry fault current and to withstand the magnetic forces of such current”.

As can be seen in other code articles, the .10 section of the article is generally used to describe the uses permitted for a wiring method or material and the .12 section is reserved for the uses not permitted for a wiring method or material.

In the 2011 NEC®, both the uses permitted and not permitted for cablebus were located in 370.3. In the 2014 NEC®, the uses permitted were relocated to new section 370.10 and the uses not permitted were relocated to 370.12 to align with the majority of other NEC® articles.

Below is a preview of the NEC®.  See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on the “free access” tab and select the applicable year of NFPA 70 (National Electrical code).

2011 Code language:

370.3 Use. Approved cablebus shall be permitted at any voltage or current for which spaced conductors are rated and shall be installed only for exposed work, except as permitted in 370.6. Cablebus installed outdoors or in corrosive, wet, or damp locations shall be identified for such use. Cablebus shall not be installed in hoistways or hazardous (classified) locations unless specifically approved for such use. Cablebus shall be permitted to be used for branch circuits, feeders, and services.

Cablebus framework, where bonded, shall be permitted to be used as the equipment grounding conductor for branch circuits and feeders.

2014 Code Language:

370.10 Uses Permitted. Approved cablebus shall be permitted:

(1) At any voltage or current for which spaced conductors are rated and where installed only for exposed work, except as permitted in 370.18

(2) For branch circuits, feeders, and services

(3) To be installed outdoors or in corrosive, wet, or damp locations where identified for the use

370.12 Uses Not Permitted. Cablebus shall not be permitted to be installed:

(1) In hoistways

(2) In hazardous (classified) locations, unless specifically approved for the use

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370.10 and 370.12 Cablebus. Uses Permitted, Uses Not Permitted.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Which of the following is true of cablebus?

A: It can be used in hoistways.
B: It can be used in any hazardous location.
C: It can be used for services.
D: It is NOT permitted for branch circuits.
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