Routing the Wire and System Termination

Pre-wire Video

I use a front projection system in my theater and I wanted to make sure I had pre-wire to alternate locations in the ceiling just incase I change the projector and it has a shorter throw distance. As you can see in the photo, I have two locations. 2x4’s are nailed across the ceiling trusses to box them in. This provides a sturdy surface in which to bolt a projector. 115 volt outlets are installed for both locations and the low voltage boxes are installed on the other side for separation. For the wire installation, I pre-wired one 35ft. Blue Jeans BJC Series-2 HDMI cable, one 35ft. Impact Acoustics Sonicwave component video cable, and three un-terminated runs of RG6-QS that will remain coiled up in the ceiling. The use of commercial grade outlets is highly recommended for projectors because the power cord hangs upside down.

The correct way to route wire

Having been in many new construction homes, I am often appalled when I see wire installed by the so called “professional low voltage specialist”. If you are going to hire someone to pre-wire your home find a professional A/V installation specialist. Pre-wiring for A/V is different than pre-wiring for phones, alarms and computer networking. Wire installations for A/V systems need to be clean and routed correctly because your systems performance relies on correct installation. Planning, patience, and care are necessary to ensure top performance from your pre-wire installation. First rule: never cross high voltage electrical wire with your low voltage pre-wire. There is always a way to keep your pre-wire away from romex wire runs that feed electrical outlets and lighting. Remember when I told you to add 30-50% to you wire length totals? Now you get to find out why. As shown in the picture, the pre-wire is routed up through the top plate of the wall. As you can see, there is a romex wire run installed on the top plate. The pre-wire is installed at least 12-inches above the romex. The white RG6-QS wire is pulled away from the romex and then stapled above. Note the gentle sweeping bends in the RG6-QS. Never kink or bend a wire with too small of a radius. All wire runs are pulled lightly then stapled to the framing for a nice clean run. Romex staples are used to secure the wire to the framing and the staples are nailed in just enough to hold the wire.

When the wire is secured to the framing, you should be able to lightly pull on the wire and it should move freely inside the nailed staple.

There are many types of wire fasteners, I prefer the romex staples because they are faster to install. Use what works for you. With the wire secured to the side walls, you don’t have to worry about someone accidentally breaking or stepping on a wire because it’s out of the way. There is always a way to avoid crossing romex, sometimes you just need to think about it and be a little creative. One way is to suspend the pre-wire over a romex run. In the photo, the pre-wire is suspended 18-inches above the romex. Staple each wire to the truss cross brace then construct a simple sling with some left over stiff wire (12 AWG romex works). Wrap the stiff wire down each side of the pre-wire and then staple it above. This will relieve tension on the pre-wire run when suspended. If you plan on installing in-wall or in-ceiling speakers, the same rules apply. Routing pre-wire the correct way takes more wire but your installation will be cleaner and your system will be less likely to develop hum, buzz or noise in the video image because you took the time to do it the correct way.

Don’t get my wiring dirty

Now that you have completed your nice neat pre-wire, the last thing you want is the dry wall installers mucking it all up. If you bag and tape your pre-wire before sheet rocking and finishing, you will be thanking yourself. Another thing you need to realize is that many in the construction industry know little about the wiring you just installed. They may believe it’s nothing more than electrical wire. If you don’t want boots tromping all over your wire you may want to pin them up to the framing while your room is under construction and supervise the installation of the insulation and sheetrock.

One Last Word About Electrical

The electrical system that feeds power to your home theater should be a consideration in new construction homes. Obviously, in retro homes it may be harder to update the electrical system but it can be done. I recommend a minimum of one dedicated 20 amp circuit for audio, one 15 amp circuit for video and one circuit for lighting. All circuits should have independent Hot, Neutral and Grounds: thus the name dedicated. If you plan on using a dimmer control for your lighting, make sure the dimmer is high quality. Cheap dimmers can introduce hum and buzz into the system. If you plan on installing home theater chairs with electric recline mechanisms, plan for the placement of a 15 amp outlet in the floor at the position of the chairs.

System termination

After your room’s construction is completed, it’s time to terminate your system’s components. Many installers like to use wall plates with binding posts for a clean look. I don’t like this approach because it adds four more termination points for the speaker wire. Using binding post plates with speaker wire, you will have the connection at the receiver or amplifier, front of the plate behind the A/V rack, back of the plate at the A/V rack, back of the plate at the speaker location, front of the plate at the speaker location and finally the binding posts on the speaker. That’s six termination points, if you are counting for one speaker! Instead of the binding post wall plates I prefer to use pass through wall plates. With the use of a pass through plate, you only have two termination points per speaker, one at the binding posts of the receiver or amplifier and one at the binding posts of the speaker. Wire termination to A/V equipment in the rack should be neat and well organized. Again there is always a way to route interconnects and wire away from power cords in the A/V rack. If you do need to cross a power cord do so at a 90 degree angle. Never run interconnects and power cords side by side. Interconnects to receivers, amps, DVD players and other equipment should be relaxed with gentle bends, don’t try to make too short of a cable reach.

You can keep your cabling neat and together a number of ways. Split Loom is the black plastic tube that is split down one side and has a corrugated look to it. It is available in sizes from 1/4" to 1-1/2”. The use of split loom will keep cabling neat and give the back of your rack a high tech look.

Another option is to use Velcro tie straps to keep your cabling looking neat and together. These are available at most pro sound stores. The last option is plastic zip ties; you can use these (I do) but be careful. Don’t pull them tight around your cables, only enough to hold them in place. The small teeth on them will cut your cables if you pull them too tight.

Attention to detail

There are many was to dress up an installation. I don’t like the idea of running cabling and power cords together down the center post of a projector mount for the reasons previously explained in the article. With a little patience and creativity you can come up with great looking alternatives that will improve your systems performance. A small detail like painting your outlet covers the same color as your walls and ceilings or selecting outlets that closely match your décor are little details that will polish and give your home theater a finished look. Pre-wiring a home theater yourself and doing it the correct way can be very rewarding. Careful planning, patience, research, and attention to detail are the keys to a trouble free high performance home theater installation. Be sure to check with local your local building codes before you begin a pre-wire project. If you are gong to hire a custom installation A/V professional you now know how wiring should be routed and installed and that can prevent costly mistakes.