Many guidelines and installation procedures for single-family homes also apply to multiple dwelling units
Single-family homes aren't the only dwelling units in which you'll be able to put your home technology knowledge to work. Multiple dwelling unit (MDU) properties have many of the same needs as single-family properties. And just as homeowners recognize the value in outfitting their homes with the latest voice, data, audio, video, and security technologies, many MDU owners also recognize the value in outfitting their properties with the latest in technology.
This last installment of a 12-part series of articles meant to prepare electrical contractors to take the test to be certified as home technology integrators (HTIs) addresses installation issues in MDUs. While many of the installation and service procedures are similar to those for single-family homes, which were discussed in detail in the previous articles in this series, MDU work offers some special challenges. This article addresses those issues and wraps up our yearlong coverage of the wired home.
Point of entry and demarcation points.
In MDUs, the point where the telephone company service cable meets the customer premises equipment is called the main point of entry (MPOE) or the demarcation point. The MPOE is the transition point from telephone company equipment, which is typically located on the outside of the MPOE, to building management ownership equipment, which is often installed on the inside of the MPOE. The MPOE provides a mechanism for bringing the communications provider and customer equipment together in a safe, structured manner. In all new construction, the MPOE is usually located within 12 in. of the point of cable entry to the point at which the telephone service cable crosses the customer property line, or the closest practical point at which the telephone cable enters the building.
In most modern MDUs, you'll find the MPOE in a secure, climate-controlled room, usually in the basement. All of the service provider's cables will connect to a telecommunications rack in this closet. The punchdown block, which allows multiple input cable pairs to be distributed to various units within the building, is installed in the closet and on the rack.
Punchdown blocks available for use in a telecommunications closet include the following types:
Type 110 blocks are based on the latest technology. These units support higher bandwidth communications and networking standards, including Cat. 5e and Cat. 6 networking.
Type 66 blocks are used in many voice-only wiring systems where high-speed data networking won't be required.
You may need to include filters in the telecommunications rack for digital subscriber line (DSL) broadband Internet connectivity. These filters allow DSL Internet connectivity and voice communications to share a single pair of copper wires by preventing the high-frequency DSL carrier interference signal to leak through.
Calculating the total electrical power requirements for a telecommunications rack is rather easy. It's advisable to create a spreadsheet that lists the power requirements for all devices located in the telecom rack. Once the listing is complete, it's simply a matter of summing the power requirements column on the spreadsheet to determine the proper size electrical feed required for this unit. The power requirements for individual rack components can be found on labels or plates affixed to the rear or bottom of each piece of equipment.
You should include the power requirements for all equipment within the MPOE, including climate control, security, and automation equipment. You should also take into account the load requirements of an uninterruptible power supply unit. It's also a good idea to install an instant equipment shutoff device, or emergency power off (EPO) switch, that cuts power to circuits in the event of fire, flood, or other disaster.
It's important to note that when multiple service providers bring their cables into the building, each will make use of an MPOE. All providers will be brought together in the main distribution frame (MDF) where telecommunications, Internet, and other communications providers will house their customer premises equipment. It's your responsibility to provide the backbone cabling system that interconnects the telecommunications closets, equipment rooms, and entrance facilities located throughout the building.
Route cables from the MDF to intermediate distribution frames (IDFs) located on each floor where each telecommunications and Internet vendor can designate and split off cable pairs for individual customers. Cables that pierce floors, walls, and other fire-stop structures must be carried within conduits.
In some instances, building layout or unit density may indicate the need for additional distribution frames. In this case, satellite distribution frames (SDFs) may be constructed on floors where physical distances or the number of customer lines to be installed exceed the limits of an IDF. Depending on the communications service and provider involved, trunk cables may consist of a bundled 50-pair copper cable or a fiber optic cable. Cables that run vertically between floors of the building are called risers; those that stretch horizontally within the confines of one floor are called ties. All of these cables must be plenum rated.
The use of fiber optic cables is becoming more popular in apartments and condominiums. In many cases, the fiber will be used as part of the backbone wiring plant, connecting the MDF to IDFs, and on to SDFs. In these installations, it's necessary to install a switch or router that also performs a media conversion.
You must not route telecommunications or Internet access cables in the same conduits or cableways as electrical service cables. In addition, you should limit the distance from the distribution frame to the telephone instrument to less than 328 ft. Connect the cable from each wall outlet to the intermediate or satellite distribution frame using a “home run” configuration rather than a daisy chain.
Locate central controllers — whether telecommunications or Internet — with the distribution frames nearest the individual residence. If you can keep overall cable runs within allowable parameters — 462 ft from MDU to wall plate and 328 ft from controller to instrument — then you can locate the controllers in the same room as the MDF and MPOE. If the building you're working in is large and you can't meet these required cable run lengths, you may have to install multiple controller locations within intermediate or satellite distribution frames.
An auxiliary disconnect outlet (ADO) provides an easy way of disconnecting or redeploying lines in locations that are readily accessible to telephone and Internet service technicians. The ADO is located on the MDF or distribution device and provides a connection from the MPOE via the ADO cable. The ADO isn't a requirement in installations where the MPOE and MDF share a room, but provisions for the ADO are part of most telecommunications equipment, and the ADO may be used with no detrimental effects even when it isn't strictly necessary.
It's advisable to install wall plates for telecommunications and Internet service in the same position in all units. This not only creates a uniform, equal appearance, but it also allows for increased serviceability because technicians won't have to spend unnecessary time searching for wall plates in the event of service disruptions or changeorders. Uniformity in design will also ease calculations of overall cable length and wire order requirements.
The importance of maintaining firestops in an MDU can't be overemphasized. Any penetration or coring made to ceilings or walls during the installation of conduit or cable, whether during installation or troubleshooting, should be repaired with approved firestop material. Firestop systems are designed to protect against the passing of fire, deadly gases, and toxic smoke through openings that exist in joints and gaps in fire-resistive walls, floors, and floor/ceiling assemblies. The International Firestop Council, a not-for-profit association of manufacturers, distributors, and installers of fire protective materials and systems, is a good resource for additional information on firestop systems.
Basic telecommunications testing equipment used in single-family dwelling units, including network tone generators and butt sets, can also be used in MDUs. These devices not only help you during the installation phase of the project, but they also help the technicians who work for the building owner or communications service providers troubleshoot the system after it's up and running. One of the most important requirements is that you properly label the punchdown blocks and patch panels during the installation phase of the project. This will allow the technicians, especially those who will be working at a particular facility on a frequent basis, to efficiently troubleshoot the system during maintenance or emergency repair situations.
Service provider access.
There are a variety of reasons to house telecommunications and Internet service equipment in dedicated rooms. Security, climate control, and electrical service continuity are all key considerations to take into account during the design and installation phase of the project. Another crucial consideration is the topic of access. Depending on the policies set forth by the building owner, service providers may be issued keys to the MPOE, MDF, and any IDF facilities where future access may be required. Alternatively, the building owner may set policies and procedures that direct a building employee to provide access to these rooms on an as needed basis. In either case, the building owner must provide access so no tenant or unit owner is left without communications for extended periods of time.
As you can see, the design and installation procedures for MDUs aren't much different than working in a single-family home. The occupants in these dwelling units are looking for the same technology features individual homeowners crave. And who better to design and install the technology systems for these facilities than a qualified home technology integrator (HTI).
Dusthimer is publisher of Cisco Learning Institute, York, Pa.