by Jeff Fisher
What's the most common piece of "20/20 hindsight" when it comes to how low-voltage wiring is done in a home? Wishing that there was better wiring "access" to the head-end from the attic and crawl-space. The corridor between your attic, your head-end, and your crawl-space is the real "information highway" in your home. This area will have to take a lot of wires, both during and after construction.
So how do you provide easy wire access between these three areas? Install wiring chases, that's how.
This application note describes how and when to install wiring chases in your new home.
What is a Chase?
Chases are basically large conduits strategically placed in your walls where large numbers of cables gather and run together for short distances. There are two, relatively "semantic" differences between a chase and a conduit:
- A conduit usually goes from a wall plate or some other "firm" destination, to another solid destination. (I.E.: From a wall-switch box to a breaker panel.) While a chase often simply goes from one open space to another. (I.E.: From the crawl-space to the attic.)
- A conduit usually smaller than a chase (less than or equal to 1") and carries fewer wires. (Less than 4.)
On the more practical side, my feeling about the main differences between a chase and conduit is that you can put conduit just about anywhere because you are drilling relatively small holes in the studs, rafters, and/or joists. But chases are large enough that you have to be a bit more careful about where you go punching the holes!
Where to Locate Chases
When someone brings in their plans to our showroom to begin the process of "specking out" their new home for low-voltage wiring, the first thing we look for is a good place for the headend. The primary consideration here is access, though the walls, to the attic and crawl-space. In a 2-story home the choice is even more difficult as we try to find a location with a common wall. This is so that cables can run straight up inside a wall all the way from the crawl-space or basement to the attic.
Why is this "common wall" so important? If you asked this question, you need to see a fully-wired house just before the walls are closed up. There are a lot of wires in the walls. Simple paths from major spaces like the crawl-space and attic really clean up and simplify the cabling. And the simpler it is, the less likely that there are mistakes. And just as importantly, a common wall greatly simplifies the addition of cables after the walls are closed in.
Chases just take this "common wall" approach to it's logical conclusion. Provide a really simple, clean, easy access way to get wires up and down (or across in unusual situations) between these "high traffic" areas.
Once the appropriate wall is located, you'll need to work with your builder to "stake out" one or two stud bays in this wall for your exclusive use. While you can work around a little AC in the stud-bay, plumbing would definitely be in the way. The builder will have to approve of you drilling up to four 2 1/8" holes through the top and bottom of the stud-bay. If this is a load-bearing wall, the builder may need to add some compensating structure.
The chases will go from the attic to the headend, and from the headend to the crawl-space. How many chases you need will depend on the size of your home and how much low-voltage wiring you are putting in. (See below.)
What Materials to Use for Chases
You can get these materials at your local home-improvement store or lumber-yard:
- PVC Pipe, 1 1/2" Schedule 40. Comes in 10 foot lengths for around $5.
- 1 1/2" Female-Female Splices. About $2.
- 45 degree 1 1/2" Female-Female Elbow fittings. About $2.
- PVC Cement
- 1/16" Steel Nail-Plate
- A 2 1/8" Boring Drill Bit
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