Kee Electric – Design-build Services, Nashville TN

:: What is structured cabling?

Modern computer LAN (local area network) wiring has the concept of structured cabling.

With today’s high speed networks, people realize that the networking system must be broken up into shorter chunks that allow workstation wiring to be concentrated, with each cable length short enough to support the high data rate.

Based on aforementioned reasons, structured wiring standard has been developed to help define a computer wiring system that stays within the maximum wiring distance for various LAN topologies. For example, the horizontal cable wiring length is 100 meters for 100BaseT networks.

:: What do we do to observe the 100 meters wiring standard?

In order to achieve the wiring concentration standard, telecommunication rooms (wiring centers) are placed at planned locations in a building. These telecom rooms are then interconnected to provide the total network connectivity for the building.

This can be explained in a three stories building. At one same corner of each floor, a telecom rooms is constructed; these telecom rooms are then connected by backbone wiring (cables run vertically through the floors and link all telecom rooms together).

On each floor, a telecom room concentrates all workstation cables for that floor. Each workstation has a wall mounted jack. The network cable is terminated at that jack and runs directly to the telecom room. The cable may run in wire trays or conduit, or be draped over supports such as a drop ceiling. For larger floors, more than one telecom room may be needed.

:: Horizontal Cabling

The horizontal wires, which run from workstations on the same floor to the telecom room, are then terminated on punchdown termination, or directly onto a patch panel. The punchdown terminations or patch panels could be rack mounted (19″ or 23″ racks), cabinet mounted or wall mounted.

In the telecom room, network equipment such as a hub or switch is connected to each station cable, which electrically terminates the cable run. The hub or switch then passes the computer signal on to other work stations or servers, or even to other telecom rooms for ultimate connectivity with the entire network.

:: Vertical Cabling (Backbone Cabling)

Telecom rooms on each floor are then connected together by backbone cabling (also called vertical cabling for floor to floor connections). These backbone cablings typically are done from floor to floor to floor.

Usually telecom rooms should be located directly above one another in order to minimize the cable runs length, but this also varies from building to building.

With the emerge of Gigabit Ethernet and 10 Gigabit Ethernet, fiber optic cable is the most appropriate choice for backbone cabling since they provide much higher bandwidth than traditional Cat5, Cat6 or even Cat7 twisted pair copper cables. Another advantage of fiber is that fibers can run much longer distance than copper cable, which makes them especially attractive for backbone cabling.

:: The difference between backbone cabling and horizontal cabling

Since backbone cabling typically passes through from floor to floor, the cables used for backbone cabling have very different requirement than the horizontal cablings.

1. Fire ratings. Backbone cables must have standard imposed fire rating specifications. Typically this is OFNR (Optical Fiber Non-Conductive Riser) rated. If the backbone cable passes through plenum area (spaces in the building used for air return in air conditioning), the cable must be OFNP (Optical Fiber Non-conductive Plenum) rated.

2. Physical securing. Physical securing for vertical riser cables is also different than horizontal cables. So is the cable strength, since vertical riser cables need to have enough strength to support its own weight.

It is always recommended that the construction work you plan on doing in your house is drawn by a professional such as a residential designer or an architect. There are no licenses required to prepare drawings for a home design project or any kind of project for that matter, specially if they are considered standard construction and the details for construction follow the general guidelines from the city or county. But sometimes depending on the job, even when the job seems simple, the city and county officials ask for the stamp and signature of a structural engineer. That is the only license anybody needs to officially submit plans at the city or county offices and to get them approved. If the designer follows the city standard details and notes, the project can be approved easily and sometimes even without a structural engineer’s stamp. It depends on the project.

Hiring someone who is not a residential designer or architect to prepare your plans is not advisable. There are construction companies called “design build” that offer design services along with their construction services and guess what? They do not emphasize on the design but the construction because that is where they make their money. So they really do not care about the look or the feel of the projects in terms of design. Do not hire contractors to prepare your home design layouts because contractors build and their specialty is not ‘design’. Get a residential design professional to design your addition or remodel and to prepare your home design plans and then hire a contractor to build the project.

In the state of California, as well as in many other states, there is no license required to prepare plans, to submit them at the city/county or to even get them approved for construction. But not everybody can do it either because it is not that easy. Home or residential design is a very specialized kind of field. When you hire someone who does this kind of work for a living, not only they should know about home design and everything related to it but they usually also know how to work with the city and county officials, which is a job in itself and not very easy for regular people. Residential designers should know what is required for the different types of home or residential design jobs (remodels, additions, new construction, etc.) and they can usually expedite the process which is usually a tedious and boring ordeal.

If the residential designers or architects do not hire outside help to take care of the submittal process, they are the ones who have to spend hours at the city and county offices waiting to meet with the different officials from each and every one of the disciplines to make sure they all approve and stamp the plans, so you can get a construction permit. Believe me, you do not want to do this yourself. If an inexperienced person meets with the officials and he or she does not provide the answers to the questions the officials have at the time of the submittal or on their correction sheets, they would have to get them and come back as many times as necessary until the officials are satisfied with the answers, which would unnecessarily delay the process. If the officials notice this person has no clue, you can rest assured, they will not make it easy for you.

Another reason why you should hire a residential designer or architect to prepare your plans is the fact that they can also refer you to consultants they work with like soils engineers (if the city requires a soils report), land surveyors (if the city requires a property line survey or topography map), energy consultants who prepare the energy calculations showing how much energy your project would save or waste which is required no matter how small the project is, etc. Residential designers and architects usually have a team of consultants they work with which is always a plus. You never know what is going to come out when you submit the plans to the city or county, so having a team of professionals handy is a plus.

A residential designer’s job is to prepare your home design layouts first and later on the construction documents required to get approval from the city or county officials, whichever has jurisdiction. Never let anybody prepare plans for you and just give them to you without the approval stamps. Their job is done only when all the disciplines at the city or county have reviewed and stamped your plans as approved.

Residential electrical systems may not contain some of the complexities of commercial or industrial control systems, but the risk associated with failures may be even higher and recognizing faults and potential dangers can be a daunting task for the average homeowner. Knowing how to recognize a possible hazard before it occurs can be as easy as following a few key steps if you know what where how and when to look.

A visual inspection should be performed annually, and followed by a licensed electrician if anything seems questionable. One of the first things to look for would be dimming lights. This could be a sign of a loose or weak neutral, often occurring the same time a refrigerator , ac system, or other large load comes on. A visual electrical evaluation should also include removing the cover from the service panel and looking for traces of arcs or burn marks, without putting your hands or other tools inside and always turning the power off first. Testing individual outlets and gfci receptacles requires a plug tester, available at any hardware store for about $5. Typically a plug tester will have three small lights on it and a legend as to which pattern of lights is correct and which is not. I also recommend gently shaking the plug tester while it is plugged in to check for loose connections. Loose connections on a receptacle can result in unnecessary heat build up and fire. Do not plug more appliances into an outlet then it can handle, put your hand near it, if its warm to the touch, its too hot, use a surge strip. Devices and appliances that have large transformers on the plug should not be plugged in near curtains. If you have the type of air freshener that plugs in and releases a timed fragrance throw it away (please). I have personally seen them cause more then 1 fire. Don’t plug in more then one transformer to a single electrical outlet. Put the curling iron away, even turned off sitting next to the sink there are risk. Use the appropriate sized cords, generally speaking extension cords are for temporary 1 time usage, and not designed for prolonged use. Finally have your home checked out every few year by a trained technician.

Electrical safety in the home is as easy as being aware and conscience, if your not sure, ask, and change those batteries in your smoke detector.