Planning on running wire through cubicle walls in an office? Make sure you’re familiar with the applicable standards and Code sections.
Running data cables and power conductors through furniture wireways is essentially the same as running them through any other types of wireway, except the space in furniture pathways is generally far more limited than in most other circumstances. As such, the size of access openings and tight bending radii become primary concerns in protecting against wire damage.
To better understand these issues, let's go through some of the codes and standards regarding these installations, as well as some design and workmanship issues.
Let's begin by looking at NEC Art. 605, Office Furnishings (Consisting of Lighting Accessories and Wired Partitions). This article covers the installation of “electrical equipment, lighting accessories, and wiring systems used to connect, or contained within, or installed on relocatable wired partitions.” In other words, this article applies to the standard, freestanding cubicle partitions found in office buildings across the country. The NEC classifies these partitions (and their many variations) as furniture.
The provisions of Art. 605 include the following:
Partitions may not extend to the ceiling, except by special permission.
Internal wireways must be identified for their use.
Any lighting equipment used with the partitions must be listed for that use, properly supported, and connected with a properly sized cord no more than 9 ft long. Where a cord-and-plug connection is provided, the cord shall not be smaller than 18 AWG, shall contain an equipment-grounding conductor, and shall be of the hard-usage type.
Interconnections must be identified for such use, or must be made with extra hard-usage cord with 12 AWG or larger conductors with an insulated equipment grounding conductor no more than 2 ft long and fitted with attachment plugs and strain reliefs.
Partitions permanently connected to the building must be permanently connected to the electrical system by standard wiring methods noted in Chap. 3.
Receptacles supplying power to partitions must be located within 12 in. of them.
Multiwire circuits are not permitted.
A maximum of 13 15A, 125V receptacles are permitted on any partition or group of partitions.
In addition to Art. 605 of the NEC, ANSI/TIA/EIA-569-A, Commercial Building Standard for Telecommunications Pathways and Spaces applies directly to the use of furniture wireways for the installation of data cabling. This standard is closely associated with another telecom standard, ANSI/TIA/EIA-568-B.1, Commercial Building Telecommunications Cabling Standard: General Requirements. This document standardizes design and construction practices and provides a telecommunications support system that is adaptable to change during the life of a facility. Standard 568-B covers the pathways and spaces in which telecommunications media are placed and terminated, and it outlines acceptable pathways and spaces within and between buildings, and commercial building design for both single and multi-tenant buildings.
The “Work Areas” portion of ANSI/TIA/EIA-568-B relating to furniture pathways presents the following design considerations:
At least one telecommunications outlet box location shall be planned for each work area.
This location should be coordinated with the furniture plan. A power outlet should be located nearby.
Control center, attendant, and reception areas shall have direct and independent pathways to the serving telecommunications room.
The bend radius of the furniture pathways shall not be less than 25 mm (1 in.).
Furniture spaces designed to house slack storage, consolidation points, or multi-user telecommunications outlet assemblies shall provide space for strain relieving, terminating, and storing slack for the horizontal cables.
Slack storage and furniture pathway fill shall not affect the bend radius or termination of the cable to the connector.
You must meet the minimum separation requirements of NEC 800.52.
You must install fire stopping materials per applicable codes.
Once you are beyond the critical safety and technical concerns outlined in the codes and standards, you must think about the ease of installation and eventual rearrangement of furniture when designing the layout of the partitions. Here are some items to pay attention to:
Filling a cable pathway with wires is feasible on a straight run, but you must avoid kinking at corners. Some corners may not accommodate all the cables that fit into a straight section. Solve this problem by over-sizing or under-filling the straight sections.
While most furniture panels have top pathways for cable routing — valuable for separating data cables from power cables — some specialty furniture offers “beltline” cable and power pathways at desktop height.
Computer and telephone-intensive operations can benefit from work surface cable management, which has the added advantage of out-of-sight cord and cable storage.
Make sure that any wireway in which you install wiring is listed for that purpose by UL.
Running branch circuits and data circuits through wireways embedded in furniture is not a new technology — cable installers have been using the process for nearly 20 years. Keeping cables and wires hidden and out of the way is a must in offices, but you have to understand the codes and standards that dictate their placement before you can undertake such a project.