Overhead power raceway a safe approach in TRs

From the December, 2011 Issue of Cabling Installation & Maintenance Magazine

Ensuring power cables are not draped across the floor of the telecom room is a good idea.

TAKEN FROM THE CABLING INSTALLATION & MAINTENANCE ARCHIVES.

Problem

When laying out an equipment room or telecommunications room, whether in an existing building or for new construction, designers generally specify electrical outlets to be placed 12 to 18 inches above the finished floor. Equipment that requires power is usually installed in racks or shelves with clearance behind it to allow access from the rear. This almost always results in power cords being draped across the access aisle behind the racks. Tripping over these cords can result in bodily injury and serious problems with the electronic equipment.

Solution

Most equipment racks are at least 7 feet tall. Often, a section of ladder-style raceway runs from the top of the rack to a plywood backboard or wall to provide a cable pathway and support for the rack. Install a horizontal power raceway on the wall behind the rack. The raceway should be installed at about the same height as the rack.

A single rack may need only a quad outlet. The power cords can run from the top of the rack along the ladder-style raceway to the power outlets. For large installations, run the power raceway the length of the walls or around the entire equipment room with outlets on 2- to 4-foot centers and multiple circuits to accommodate many pieces of equipment.

Procedure

1) Use 12-inch ladder-style raceway from the top of the rack to the wall. This raceway will provide adequate separation of power and other cables.

2) If your racks are 7 feet tall or shorter, place the power raceway just above the ladder-style raceway. If your racks are 8 feet tall, install the power raceway just below the ladder-style raceway brackets (at about 6 to 6-1/2 feet above the floor).

3) Tie-wrap the power cords to the bottom of the ladder-style raceway, maintaining as much distance as possible from communications cables.

4) If you use multiple circuits for adequate power distribution, alternate outlets among the circuits using different colored duplex outlets, such as black, white and brown, to facilitate identification. Label breakers should correspond to the outlet colors.

Tips Watch

I noticed a problem with the procedure listed in the November Cabling Tip (see “With NENP connectors the cleave makes the difference,” November 2011). The article states that one should cleave the fiber prior to cleaning it. The fiber should be cleaned prior to cleaving for a couple reasons. First, any residue that is on the fiber could interfere with the operation of the cleaver. Second, and most important, the fiber should never contact anything once it has been cleaved.

Todd Bastin, RCDD
Submitted via email