Planning the wire route

How close can you get to AC power wires
There are a number of good reasons to avoid AC wires. For one thing, drilling and working near AC wires increases the chance you'll accidentally damage them. Also, if you pull your wire through the same hole as AC lines, friction can wear down the AC cable's jacket, which could create a short. If you're running audio/video cables, it's especially important to avoid them, since it can result in performance-robbing interference.

Here are some rules to keep in mind:

• If AC and low-voltage wires cross, keep them at 90-degree angles.
• Don't install your wires beside AC power lines for more than 5 feet. When you have to run your wire beside an AC line, keep it a minimum of 1 foot away from the power line throughout the entire run.
• Never use the same hole to feed both AC wire and low-voltage wire.

(A) Running low-voltage cables with power cable may result in poor performance and increases the chances of damaging AC lines. (B) If cables and power cable run parallel, keep them a minimum of 12" apart. If they intersect, keep them at 90-degree angles.

Can I run low-voltage cables together?
Yes, you can safely run audio and video in the same bundle as security, phone, data, and other low-voltage wire. If you're working in new construction, make sure that no other subcontractor is planning to use that hole for their run.

Once you've chosen the locations for your speakers, controllers, outlets, and audio/video gear, you need to figure out how to run the wire. Where you route your wire will depend on a number of factors. Are you working in new construction with exposed studs? If you're working in a finished home, do you have access to crawl spaces and unfinished basements? Below, we've offered some specific tips for both new construction and finished homes.

Also see The rules of routing wire for additional guidance as you plan your wire routes.

Wire routes in new construction
Because wire costs money, you'll want each wire run to be as direct as possible. However, in order to avoid AC power wires, or keep from drilling holes through every stud all the way around your room, you'll probably have to compromise. The trick is to minimize your work, not your wire length.

Although it may seem like wasting wire, your attic, basement, or crawlspace can provide you with great wire pathways — where you don't have to drill, you simply hang your wire in clamps and brackets. Plan to use these spaces as much as possible, even if it means a much longer length of wire. The time you save not drilling studs and joists can more than compensate for the longer wire runs.

See page 7 for step-by-step advice on the process of wiring new construction.

Wire routes in finished construction
While installing in-wall wire in a finished home can be trickier than in a home still under construction, there are a few ways to make it easier. If you can run your cables in places that won't require drywall repair afterwards, you can save yourself lots of time and effort. Also, avoid exterior walls when possible. These walls have extra bracing and insulation which can make installing gear and running wire more difficult.

We've listed some common options below. Take a look and consider which one(s) would be the best option for your house and setup.

• inside the wall
• under your carpet
• behind a baseboard, door jamb, or crown molding
• through a heating or air conditioning vent*
• inside cabinetry, bookshelves, drawers, or closets
• through a crawl space, or unfinished basement or attic

*Note: Use wire that meets local building and fire code. If running wire in heating/AC vents, use "plenum-rated" wire — CLP2 or CLP3.

See pages 8-9 for more tips on working in a finished home.

Making sure you have enough wire
After planning where you're going to route your wire, calculate how much you'll need. Work your way from point to point carefully, without overlooking anything. You may want to sketch out a wiring "map" — a record of what you're installing in each room and all of the cables, brackets, and other items you'll be installing. If you work from floor plans, use a scale ruler. Better yet, walk through your home, pacing off each run and thinking through where the wire will have to turn a corner or go up or down a wall. Convert your paces to feet and keep a record of each run. Here are five keys to estimating wire runs:

1. Careful inspection: Make a note of which direction ceiling joists run and where other structural obstacles might lie.
2. Pace off the entire route: Don't guess, pace off everything. Estimate small runs first and double-check yourself for consistency.
3. Measure the ceiling height: Don't guess at the ceiling height, measure it. If you "eyeball" a vaulted ceiling, you're asking for trouble.
4. Allow extra wire for termination and connection to your gear. For example, if you intend to install speakers and volume controls by yourself, allow 4-6 feet of extra wire so you can set the device on a ladder or on the floor while you hook it up. Consider leaving even more wire for an in-ceiling speaker installation, so you can wire your speakers while standing on the floor (instead of precariously balanced on a ladder).
5. Allow 10 to 15 percent extra: Your planned wire route might be thrown off by an unexpected obstacle. To be safe, buy a minimum of 10 percent more wire than you think you need. Some professionals use a 20 percent fudge factor, but that's easy for pros to justify, since they can use the excess wire on their next job.

Here's an example of how to calculate a wire run from a receiver to a right in-ceiling surround speaker:

The same technique should be applied to a multi-room system. Depending on your setup, this process might be a bit more involved. Here's an example of a wire run in a one-story home, from a receiver in the family room to a volume control and speakers in the home office.

So for this room you would buy 78 feet of 4-conductor speaker wire and 69 feet of 2-conductor wire, or 147 feet of 2-conductor wire.

Many professional installers simply take the longest speaker run (in this case, 39 feet) and use that for both speakers — or for all 5, 6, or 7 speakers in a home theater setup. Why? If the signal travels the same distance to each speaker, it will arrive at each speaker at the same time, which gives you perfectly timed, in-sync audio. However, for relatively small variances in length, most people probably won't be able to hear the difference. Plus, using the longest run for all speakers in a home theater setup could add quite a bit to your wire costs, and leave you with many extra feet of wire to dress and hide inside the wall. For optimum performance, equal lengths of wire are ideal, but you'll have to decide if that makes sense for you.