5.3 Wiring Closets

5.3 Wiring Closets

A wiring closet is a central junction point for the wiring and wiring equipment used to connect devices in a local area network (LAN). It is the centre point of a star topology.

A wiring closest can either be a specially designed room or cabinet. Normally, the equipment in a wiring closet includes:

  • Patch panels
  • Wiring hubs
  • Bridges
  • Switches
  • Routers

Placement of Wiring Closets

One of the early decisions that must be made when planning a network is the location of the wiring closet(s), since this will be where many of the networking devices and cables will be installed.

The most important decision is the selection of the Main Distribution Facility/Facilities (MDF) and any Intermediate Distribution Facility/Facilities (IDF) if required. A good way to start looking for a potential main wiring closet location is to identify secure locations that are close to the Point of Presence (POP). The selected location can serve as either the sole wiring closet, or as the MDF, if IDFs are required. The POP is where telecommunications services, provided by the telephone company, connect to the building’s communication facilities. It is essential that the hub be located near it, in order to facilitate wide area networking and connection to the Internet.

 Wiring Closet Regulations

Any location selected for a wiring closet must satisfy certain environmental requirements that include, but are not limited to, power supply and heating/ventilation/air conditioning (HVAC) issues. In addition, the location must be secure from unauthorized access, and must meet all applicable building and safety codes.

Any room or closet that is chosen to serve as a wiring closet should adhere to guidelines governing such items as the following:

  • Materials for walls, floors, and ceilings
  • Temperature and humidity
  • Locations and types of lighting
  • Power outlets
  • Room and equipment access
  • Cable access and support

Floor coverings should be tile, or some other type of finished surface. This helps control dust, and shields equipment from static electricity.

Rooms must not have a dropped, or false, ceiling. Failure to observe this specification could result in an insecure facility, allowing possible unauthorized access.

How Many Wiring Closets

It is not unusual for large networks to have more than one wiring closet. Usually, when this occurs, one wiring closet is designated as the main distribution facility (MDF). All others, referred to as intermediate distribution facilities (IDFs), are dependent on it. A topology such as this is described as an extended star topology.

TIA/EIA-569 states that each floor must have a minimum of one wiring closet and that additional wiring closets should be provided for each 1,000 m2, when the area of the floor that is served exceeds 1,000 m2, or the horizontal cabling distance exceeds 90 m.