There are two steps to installing a cabling system: installing the wires and connecting the wires. The standard for structured cabling systems is the EIA/TIA 568. This standard, which identifies how many outlets should be installed, gives two options for wiring outlets.
Things You'll Need
- Wire in an unreel box
- Electrical fish tape
- Wall sockets
- Punch down blocks
- Manufacturer's punch down tool
- Wire cutters
- RJ-48 plugs
- RJ-48 crimp tool
Design the outlet locations. The EIA/TIA 568 standards recommends two outlets per 9 square meters or 95 square feet of office space. Each outlet should have one voice and one data socket. With a floor plan of the building, identify the proposed locations of the outlets by using small colored circular labels.
Plan how the wire will run from the central wire point. Use cable trays or conduit if possible. Be sure not to run wire through air ducts or plenum air spaces unless it has the correct fire test rating. Check local building codes for proper wire regulations. Remember the standard limits the maximum cable run to 90 meters or about 295 feet.
If you plan to pull more than one wire at a time, each wire will come from a different reel or unreel box. Label the unreel box and label the end of the wire so they can be identified after pulling.
Pull the wires carefully, using an electrical fish tape or fish cord to get through conduit, over ceilings or behind walls. Leave enough slack at each end for the connection. Do not bend the wire beyond the minimum bend radius as defined by the manufacturer.
Label the wires uniquely at each end. Make sure to use special wire labels or crimp on labels. Remember that Teflon used for fire-rated wire is slippery and normal labels might fall off.
Understand the two wiring standards. The EIA/TIA 568 standard gives two options for wiring sockets: 568-A or 568-B. The central two pins, pins 4 and 5, are reserved for a telephone and will always be the blue/white-white/blue pair. The last two pins, pins 7 and 8, will always be the white/brown-brown/white pair. EIA/TIA 568-B specifies pair two should be on pins 1 and 2. These are the white/orange and orange/white wires. Pair three is put on pins 3 and 6, surrounding the central pins for pair one. These are the white/green and green/white wires. The 568-A standard exchanges pairs two and three.
Which standard is used, 568-A or 568-B really doesn't matter as long as the same standard is used on both ends of the same wire. The 568-B standard is more common within the United States and the 568-A standard is more common elsewhere, although any building could be either. Identify if a building standard already exists by checking existing documentation or examining the installed wire. Punch down jacks at the central site will often be labeled as "A" or "B." Examining the wire labels at existing sockets will also identify A or B.
Prepare the wires for connection. Remove several inches of the outer sheath with a data cable sheath removing tool if available, or use wire cutters or scissors. Place the wire against the blades and move the cutting edge in a circular motion around the wire to score the outer sheath almost all the way through. Be careful to cut only the outer sheath and not to nick the insulation of the underlying wire. Remove the outer sheath by grabbing it with one hand on either side of the score and using a twisting, pulling motion to remove several inches of the sheath.
Punch down the wire at the central wire station. The block manufacturer will have a special tool to punch down wires onto their proprietary block. Position the wire on the block so the outer sheath is within 1.25 inches of the punch down point. The wiring block should allow you to connect the wires with no more than 0.75 inches of untwisted wire. Remember that the wires should be connected in order, white/blue, blue/white, white/orange, orange/white, white/green, green/white, white/brown and brown/white.
Connect the wires at the socket. Wires connected at a socket should be prepared in the same way, removing the outer sheath back several inches. The socket manufacturer must provide a mechanism for spitting an crimping the wires with no more than 0.75 inches untwisted. Follow the manufacturer's color scheme for using either 568-A or 568-B standards.
Prepare the wire for the plugs. If patch cables or plugs are required, they should be wired according to the chosen scheme of 568-A or 568-B. Remove the outer sheath back several inches as described earlier. Do not untwist the wires. Rather, flatten the twists by pushing them with your fingers and sort them into the correct order. For 568-B this is white/orange, orange/white, white/green, blue/white, white/blue, green/white, white/brown, brown/white. For 568-A, exchange the orange and green pairs. Note the reversal of the wires on pair one, the blue/white pair. These will connect to pins 4 and 5. There will now be several inches of untwisted wire, but be sure that the wires flatten into their correct place within 0.25 to 0.5 inches of the outer sheath.
Crimp the wires onto the plugs. Now cut the flattened, sorted wires with a wire cutter or scissors to be no more than 0.75 inches of untwisted wire. Insert the wires into the plug being certain that the wires are pushed all the way to the end and that the outer sheath is inside the plug so it will be secured by the stress relief clamp when the wire is crimped. In the case of 568-B, the white/orange wire should be on the left hand side of the RJ-48 plug with the clip of the plug facing away. Crimp the wires using the RJ-48 crimp tool.
Test the connections and the patch cables using a certified cable tester.
Tips & Warnings
- Practice stripping, flattening twists and sorting wires several times before trying to connect to sockets.
- Practice with crimping down plugs before wiring sockets. Plugs are much cheaper than sockets.
- Label every cable at each end.
- Label the punch down blocks, identifying each connection.
- Make a simple tester by crimping a short length--one or two feet--of wire onto an RJ-45 jack and wire the other end to a set of screw down terminals. Test pairs by placing a short circuit on each pair, one at a time or place high value, very different resisters between the pairs. Pairs can then be identified with a multimeter at the other end of the cable.
- Be sure to follow fire codes.
- Avoid running wires in air ducts.
- Observe the cable's minimum bend radius at all times.
- Do not use metal staples to secure the cable. Use only plastic nailed wire supports.