The Nitty Gritty

July 1, 2004
Ensuring Reliable Telephone Exchange Building Operations
When telephone equipment goes down, it often goes down like a row of dominos – one after another. Suddenly, an entire city may be without telephone service and unable to connect to the Internet.To ensure efficient and reliable telephone exchange building operations, following are some specific dos and don’ts for design consideration within telephone equipment spaces:Do not route any type of water piping over the switch. (The reason for this should be obvious.) If at all possible, don’t even route piping through the switch space. As a last resort, route piping around the switch – and show this routing on drawings so that contractors aren’t left with an option.If a roof or floor drain must be located directly over the switch, install a sealed sheet metal drain pan beneath the drain. The pan should be fitted with a pipe leading to within eight inches of the floor. While a sweating or leaking pipe might create a puddle this close to the floor, it is a better option than a pipe going straight to a drain. Also, any horizontal section of the drain pipe should be insulated.Place pipe, ducts, or any other roof penetration so that it is not above current or future telephone equipment areas.Hang mechanical items only from the building structure – not from cable racks, conduit, pipe, or ducts.Critical phasing of work is of utmost importance to ensure the telephone equipment environment is maintained. It is up to the facility manager to plan and understand how the work can be done without disruption of service. A manager should never assume that a contractor or third-party designer will handle the work in the manner of least disruption. Staging of work notes on drawings will be necessary if critical phasing is to be properly communicated.If maintenance is required on mechanical cooling units when there is no back-up cooling, it should be scheduled during cool weather months. If back-up is available, scheduling becomes less critical.If equipment must be shut down for maintenance, consider the load of the equipment. It may be necessary to limit system shut-downs to small time frames, depending on other factors, such as the time of the year.Floor fans may be used to extend work time frames, but sometimes temporary cooling units must be provided. When this is the case, it should be clearly shown on the drawings. Drainage from these units must also be taken into consideration. (Managers should be creative when organizing sources for emergency cooling. An old air handler, or even an air-conditioned adjacent space used in conjunction with floor fans, may provide adequate cooling and avoid the cost of additional equipment that may never need to be used. The objective is simply to get cooling to the switch.)If a dust partition is part of the project, the partition should be routed so that it does not cut off air supply ducts or block temperature control sensors. The needs and path of return air should also be considered.Telephone DC power rooms should be air-conditioned. Some codes also require exhausting the space of hydrogen gas, which is usually only a concern in a small, unventilated room. The Occupational Safety and Health Administration (OSHA) establishes acceptable hydrogen levels at one percent. A room containing four-percent hydrogen becomes an explosion hazard.During planning, take into account the proposed location of the equipment and of relief equipment. Try to stay away from the western exposure for relief air exhausting. Proximity of other wall penetrations should also be a consideration.Ductwork should be routed so that it doesn’t cover ceiling inserts, and this should be shown on the drawings.Ducts should never be painted in telephone equipment spaces. Paint will eventually flake off, introducing contaminants into the switch and transport space. Likewise, do not use fiber glass duct liner. Air erosion will cause the fiber glass particles to enter the switch and deposit in the circuits. If the humidity is right, these deposits can lead to a short-circuit.

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