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Welcome to our wiki. Here, you'll find guides on some basic networking concepts.

We connect Central New York businesses with Wi-Fi, security cameras, phone systems, and more.

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guides:cabling

Basics of Structured Cabling

These are the structured cabling guidelines we use for our SMB customers. They have been compiled based on a combination of our experience and a variety of established safety and best-practice standards.

This is by no means a comprehensive guide. Use at your own risk, and always check your local laws and building codes.

If you are unsure whether your cabling is safe or appropriate, consult a qualified professional.

If nothing else, remember this:
NEC 800.24: “Equipment and communications cabling must be installed in a neat and workmanlike manner.”

On Electricians

We are not licensed electricians, as that is not required in the jurisdictions in which we operate. We’ll hire an electrical contractor rather than pulling cables ourselves for large or specialized construction projects, or when doing so is required by law.

IDF/MDF Design

Leave Room for Expansion

In general, the system designer should allow room for additional future equipment to be added to all backboards and racks.

Installing Equipment Near Electrical Equipment

When installing communications equipment in the same room as electrical equipment like breaker panels, adequate space must be left around such equipment in accordance with NEC 110.26. Generally, this means a minimum of:

  • Depth: From the wall to 3 feet in front of the equipment
  • Width: 30 inches or the width of the equipment, whichever is greater
  • Height: From the floor to 6 feet above the equipment or to the structural ceiling, whichever is lower

Communications cables and raceways can be installed within these spaces, so long as room for expansion is left for the electrical equipment. For example, communications conduit that passes above or below an electrical panel should not block the panel’s knockout blanks in case they are needed in the future.

All electrical panel doors must be able to open at least 90 degrees.

Don’t Create Fire Hazards

Don’t install communications equipment (other than cables and raceways) within the opening radius of any door. Do not block or impede access to exit signs, fire extinguishers, sprinklers, or other fire safety equipment.

Backboards

Equipment in an IDF/MDF should be mounted to a backboard. We prefer readymade fire-retardant backboards available from many commercial electric suppliers. They should be 4 foot x 8 foot x ¾ inches, mounted vertically with the center point at 6 feet above the floor. Secure backboards at the top, bottom, and sides using heavy-duty wall anchors.

Equipment Racks

Equipment racks come in many shapes and sizes, and it is up to the system designer to determine what kind, if any, is appropriate for the installation. Wall-mounted racks should be mounted to a backboard. Racks designed to be secured to a floor must be secured before any equipment is installed.

Equipment in racks must either be designed for rack mounting or secured to a rack-mounted shelf. Do not use equipment as a shelf for other equipment.

Keep Patch Cables Short

When patching together equipment and/or patch panels in the same IDF/MDF, use short and direct patch cables to avoid creating wire spaghetti.

mdf.jpg

This is what happens when your patch cables are too long. Don't do this.

Installing Equipment in Restrooms

Communications equipment installed in a restroom is susceptible to buildup of bacteria and fecal matter. In restrooms that include a shower, equipment may also be vulnerable to water damage from steam. Install equipment in a restroom only as a last resort.

Selecting Cables

Copper vs. Fiber

For small/medium business clients, copper cabling is appropriate for most situations where the length of the cable run is 328 feet or less. Fiber cabling should be used for runs longer than 328 feet or any links between buildings, regardless of whether the cable is to be run above or below ground. Fiber may also be a desirable choice for links between IDFs for futureproofing or bandwidth purposes.

Shielded vs. Unshielded

As a general rule, most copper patch cables and drops can be unshielded (UTP) cable. Shielded cable should always be used for outdoor devices. We prefer to use shielded cable for WAPs and IP cameras.

Copper Conductor Material and Construction

Use cables with copper conductors only. Copper-clad aluminum (CCA) cables are a fire hazard, prone to corrosion, and tend to offer unreliable connections.

All patch cables shall have stranded conductors. All permanently-installed cables shall have solid conductors, except in situations where the cable will move regularly (PTZ cameras, etc.).

Copper Cable Standards

For small/medium business clients, Cat5e or Cat6 cabling is appropriate for most situations, as they are functionally equivalent for up to 2.5 gigabit Ethernet. Cat6a or Cat8 should be considered if:

  • a highly future-proof installation is desired
  • the cabling is being installed in a very hard-to-access location
  • a 10 Gbps or faster connection is required or may be required in the future

Fiber Cable Standards

We prefer single mode fiber for its lower attenuation and reliability over longer distances. Multimode fiber can be used for shorter intra-building links between switches or other devices. The system designer should select the appropriate grade of cable (indoor, outdoor, etc.) for the application. For long, exposed runs where innerduct is not practical, armored cable should be used.

Fire Rating

Plenum-rated cabling (CMP) must be used in plenum spaces. The most common plenum spaces are drop ceilings where the building’s air handling system does not use ducting for the air return. If you remove a ceiling tile and feel a rush of air, you probably need plenum-rated cable.

We use riser-rated cabling (CMR) for all other permanent indoor cable runs.

Color Coding

There are no industry or legal standards for color coding communications cables.

When adding new cabling to an existing structured cabling system, any color coding system used in the original installation should be followed to the best of our ability. Otherwise, we prefer the following color coding system for the copper cables and their corresponding RJ45 jacks unless doing so would create confusion during maintenance (as determined by the system designer):

  • Blue: Data
  • Gray: Voice
  • Black/White (match to ceiling/wall color): Security cameras
  • Red: Uplink from switch to gateway or other switch (patch cables only)

In situations where using this system would create confusion during maintenance, the system designer must select and document an appropriate color coding system.

When appropriate, the system designer may select colors based on aesthetics. For example, they may choose green cabling in a building with green walls and exposed communications cabling.

Raceways and Conduit

According to TIA 569:

The use of conduit as a horizontal raceway system for telecommunications cabling is considered when: it is required by code, … device densities are low, special mechanical protection is required, or flexibility is not required. In-floor conduit systems are especially inflexible as they are usually buried in concrete.

Common Raceways and Conduit

Surface-Mount Raceways

Surface-mount raceways are rectangular or semi-circular, plastic or metal raceways available at most hardware stores. These can be used for covering small groups of cables across or down a wall. We favor these for indoor installations where mechanical protection (from physical damage) is not a concern.

An example of a situation requiring mechanical protection is a warehouse with forklift or pallet jack traffic.

EMT Conduit

EMT should be used for interior installations where cables require mechanical protection. EMT conduit must be terminated with a plastic bushing to prevent sharp edges (TIA 569). It must be secured and fastened within 3 feet of a box, conduit body, or other point of termination and every 10 feet thereafter (NEC 358.30).

Rigid PVC Conduit

PVC conduit should be used for all outdoor and underground installations. Try to avoid running PVC conduit horizontally outdoors, as it tends to sag after being exposed to sunlight. Use expansion fittings at regular intervals when possible, as PVC can also expand and contract with the weather. Securely fasten within 3 feet of a box, conduit body, or other point of termination (NEC 352.30) and support as per NEC table 352.30:

Trade Size (inches)Maximum Spacing Between Supports (feet)
½ - 13
1 ¼ - 25
2 ½ - 36
3 ½ - 57
68

Preventing Water Jets from Underground Conduit

It should be expected that underground PVC conduit, no matter how well it was put together, will eventually fill with water. Be mindful that if there is an elevation change in the conduit run, gravity may cause any combination of frost, rainwater, or melting snow that rapidly seeps into the conduit to jet out of the lower end. This should be mitigated by avoiding underground elevation changes or by creating a pathway for water to drain before it exits the lower end.

Length

No section of conduit shall be longer than 100 feet between pull points, and the sum of all bends in each section shall be less than 180 degrees (TIA 569). We recognize this may be impossible or highly impractical for some underground runs. In these cases, use oversized conduit and use as few bends as possible.

Maximum Fill

When first installed, conduit shall be filled no more than 40%. While not an NEC requirement for communications cabling, we do this to reduce the stress on cables (and the installer) when pulling and to allow for additional cabling to be added later. For PVC conduit, refer to the PVC conduit size and fill guide.

Special Requirements for Conduit Terminating in an IDF/MDF

According to ANSI/NECA/BICSI 568-2006:

Conduits that enter a telecommunications room should be terminated on the wall to enable orderly routing of the cables to termination hardware within the room or routed through the room to another location.

Conduit should protrude from the floor or ceiling at least 2 feet and be securely fastened to the backboard or other support structure.

Don’t Mix Power and Data

Do not install communications cables in a raceway or conduit containing power conductors (NEC 800.133).

Other Cable Supports

The Basic Rule

From NEC 800.24:

Exposed communications cables must be supported by the structural components of the building so that the communications cable won’t be damaged by normal building use. Cables must be secured with straps, staples, cable ties, hangers, or similar fittings designed and installed so as to not damage the communications cable.

Non-Continuous Supports

All non-continuous supports should be attached to a building’s structural components and spaced no more than 5 feet apart (TIA 569).

Our preferred methods of cable support when mechanical protection is not required are J-hooks and bridle rings rated for the type and quantity of cabling being used. D-rings can be used sparingly when running small cable bundles on an IDF/MDF backboard.

All cables on non-continuous supports should be bundled neatly with Velcro strips.

Limited Quantity Cable Runs

Using J-hooks or other support methods for very small quantities of cables can be impractical. Groups of 1 to 3 cables can be attached directly to a building’s structural components using Velcro or loosely-fitting nylon cable clamps.

Cable Trays

While not a common method of cable support for our work, the system designer may choose to include cable trays when large numbers of cables will follow a single path. Every tray system is different, so be sure to follow the included installation instructions.

Preventing Cable Stress and Damage

From TIA 568C.0:

Cable stress, such as that caused by tension in suspended cable runs and tightly cinched bundles, should be minimized. Cable bindings, if used to tie multiple cables together, should be irregularly spaced and should be loosely fitted (easily moveable).

A minimum bend radius of one inch shall be followed for Cat5e, Cat6, and Cat6A cables. A minimum bend radius of 2.6 inches shall be followed for Cat8 cables. Ensure that cables are not making contact with any sharp edges, especially in aluminum-stud buildings.

Velcro vs. Zip Ties

From the BICSI Information Transport Systems Installation Methods Manual (ITSIMM):

Use hook and loop straps to secure the cables. The hook and loop straps should be evenly spaced throughout the dressed length. Hook and loop straps should be used to prevent a change in the physical geometry of the cable that typically results from use of nylon tie wraps.

There are a limited set of circumstances when nylon zip ties are appropriate, including outdoor installations. Consider the likelihood of cable stress, use your best judgement, and don't over-tighten zip ties when you use them.

A Note on Drop Ceilings

As per NEC 800.21, cabling must be installed so as to not impede the removal of any drop ceiling tiles. Do not support cables with any part of a drop ceiling.

Special Requirements for Fiber Optic Cabling

Exposed non-armored fiber optic cabling should be installed inside purpose-built innerduct whenever possible. Innerduct shall be supported at least every 3 feet and shall account for the bend radius of the fiber.

Air Ducts

Never, ever run cables inside an air duct. This is a massive fire hazard.

An Incomplete List of Things to Not Hang Cables and Their Supports From

  • Electric service entrances (NEC 230.28)
  • The outside of raceways/conduit, with the exception of vertical communications masts (NEC 800.154)
  • Drop ceiling grids and their support wires (NEC 800.24)
  • Sprinkler pipes
  • Other cables or cable bundles
  • Drywall, unless proper anchors are used
  • The cable’s connectors, with the exception of very short patch cables

Installing Cable

First, Remove Abandoned Cabling

Removing cabling that is no longer in use is not only good for aesthetics and freeing up space, it is required by the NEC “to limit the spread of fire or products of combustion within a building” (800.25). Therefore, the customer should be informed that the NEC requires that “the accessible portion of communications cable that isn’t terminated at equipment and not identified for future use with a tag must be removed” (800.25).

Pulling Cables

The end of each cable and its corresponding reel or box must be color-coded with electrical tape before being pulled. For best results, bundle the cables with electrical tape, then use lock stitch knots and ample electrical tape to secure the pull string to the cables.


Illustration of our recommended cable pulling setup.
Note the cone of tape at the cable bundle end to prevent snags.

Be sure not to exceed the maximum pull tension for the cable. When pulling through especially long or bendy conduit runs, apply cable lubricant as the cable makes its way into the conduit. You might also consider having a helper feed the cable into the conduit while you pull. Color code the spool end of each cable before cutting it. Make sure to leave pull string behind for the next installer—it might be you!

Labeling

Each cable shall be labeled on both ends with a self-laminating vinyl or heat-shrink label. If there is no existing labeling convention for the building, it is up to the system designer to create and document such a convention.

Additionally, each jack in a wall plate, surface-mount box, or patch panel is to be labeled identically to its corresponding cable. Cabling that is reserved for future use should be clearly labeled as such to avoid being misidentified as abandoned (NEC 800.25).

Dressing and Cable Management

Bundled cables in an IDF/MDF should be dressed using a cable comb. Other exposed cable bundles do not necessarily need to be combed, but should be tidy and tangle-free.

Service Loops

Ample slack should be available in service loops for every cable we run. For copper cabling, the BICSI Telecommunications Distribution Methods Manual (TDMM) recommends slack of no less than 10 feet at the IDF/MDF and no less than 1 foot at the outlet. Because we work exclusively with pre-terminated fiber assemblies, expect fiber service loops to be much larger than this. The system designer may wish to include fiber storage rings to account for this.

Copper service loops can be horizontal or vertical; fiber service loops must be either horizontal and stored on a flat surface or stored on a fiber storage ring. All service loops should be secured with 2-4 evenly spaced Velcro strips, then placed in a location that does not take up critical space (i.e. preferably not on the backboard) and is not prone to snagging or other damage.

Installing Patch Panels

Patch panels should be installed in an equipment rack or bracket. Once cables are punched down, they should be secured on the rear of the panel or by some other means so that their support does not rely on the punched-down conductors. Cables should be managed so that each patch panel can be pulled a few inches away from the rack and new drops can be added.

Installing Outlets

For wall outlets, use low voltage brackets that tighten using screws. Ensure that outlets are level, flush with the wall, and in line with any electrical outlets. Surface-mounted outlets can be installed in biscuit boxes or in gang boxes that are part of a surface-mounted raceway system.

Fire stops

Fire stops help prevent the spread of fires through cabling or openings in fire barriers. Correctly installing fire stops can literally save lives, so please take extra care to do so properly.

The Basic Rule

From NEC 300.21:

Openings around electrical penetrations through fire-resistant rated walls, partitions, floors or ceilings shall be fire stopped using approved methods to maintain the fire-resistance rating.

Identifying Fire Barriers

In newer buildings, walls and floors that are fire barriers should be labeled:

In older construction, the easiest way to recognize fire barriers is usually to look for red fire stop material that was previously installed by electricians. For walls where no previous penetrations exist, we should assume it is a fire barrier if the wall runs all the way from the floor to the hard ceiling (doesn’t stop at the drop ceiling). Fire stop should always be installed in penetrations through floors.

Firestop Types

Foam

This is like typical expanding foam but is red in color and has special fire-blocking properties. Use this around single cables that go directly through fire barriers and in the gap between conduit runs and their fire barrier through-holes.

Putty

This is similar to duct seal but is red and color and has special fire-blocking properties. Use this to plug the inside of conduit risers and through-wall conduit segments once cables have been pulled through.

When cables need to be added or removed, any putty should be removed before work begins and replaced once the work is completed.

Specialty Devices

For large groups of cables, specialty devices can be purchased that allow for easier fire stopping, often without the use of foams or putties. When using these devices, follow the manufacturer’s instructions carefully.

firestopdevice.jpg
An example of a firestop device.

Weatherproofing

Drip Loops

The intersection between an exposed cable and an external wall or enclosure must be sealed with silicone or duct seal. When an exposed outdoor cable passes into a building or enclosure, a drip loop must be created immediately before the wall penetration:

Sealing Conduit

For runs of PVC conduit that start inside a building and continue outside, you may wish to seal the inside end of the conduit with duct seal, duct tape, or by other means. This will not prevent large amounts of water from exiting the conduit, but it will minimize drafts, wildlife entry, and the accidental dropping of objects into the conduit. Any gap in the conduit’s wall through-hole should be filled with expanding foam.

After the Installation

Verification

Every new or modified drop should be verified for continuity using a cable verification tool. Clients may also request additional qualification or certification. You can learn about the differences between these processes here.

Clean Up

There are two things that clients always say they have on-site and are always broken when we arrive: ladders and vacuum cleaners. At minimum, installers should carry a small shop vacuum, light-duty all-surface spray cleaner, a roll of paper towels, and a box of contractor garbage bags.

Leave the client’s site better than you found it. They’ll be happy, and you’ll be proud of your work.

guides/cabling.txt · Last modified: 2021/03/25 19:30 by Aaron Zufall