The typical solution is to cut access holes in the walls and run the cables. In our older home, the walls are wood paneling which has been covered in heavy wallpaper and painted. Not an easy thing to repair without obvious blemishes remaining. A second option is to use the mantel to hide the cables and that is the option I chose. To my amazement, this worked very well.
This instructable will show you how to use a board, a hinge and a magnet to run cables down to the floor (left of fireplace). I also discuss alternatives to accomplish the same thing without using a hinge. Hopefully, this will provide you with some good ideas for your home.
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Step 1: How This Works
Before you decide to install a TV above your fireplace, it is advisable to place a thermometer above the mantel and make a fire. Monitor the temperature over an hour or so and make sure it does not exceed 90°F. If the temperature remains below 90°F, it is safe to mount a TV above your fireplace. It is also advisable to check your local codes for running cables.
You will also need to use a stud finder and mark the location of the wall studs. The wall stud locations will determine where you will make the wall holes for access. This is especially true for the hole near the edge of the fireplace as this is a common place for a single or double stud. In my case, there were 2 studs to the left of the fireplace which I had to drill through but that wasn't really a problem.
Step 2: Attaching the Hinge
Determine the distance from the end of the board to the point where your cables will be coming down the wall. You'll want to locate your hinge a few inches further from the end of the board to accomodate the cables. It's easiest to attach the hinge prior to cutting the access door and then remove it. In this way, you know the holes are drilled so the edges of the door line up with the rest of the board. I didn't have any rusty screws so I spattered some new ones with brown metal primer and flat black paint from spray cans.
Step 3: Cutting the Access Door
I'm guessing most of you aren't planning on using barn wood and hinges to hide your TV cables so here's a few alternative plans. My original idea was to use two 3/4" thick boards which both ran the entire length of the mantel. One board would be fastened to the wall and the front board would be held by rare earth magnets to the rear board. Magnets would be counter sunk and glued in one board and metal washers counter sunk in the other. When finished, the front board would simply snap into place and could be easily removed when necessary. The boards could have a variety of appearances from plain 4" boards to fancy trim boards.
A third option is to simply cut a groove in the wall itself and cover it with a piece of trim. This is possibly the easiest technique, however, you will not be able to easily access the cables without removing the trim. Considering the likelihood that we would be running additional cables in the future, I opted for having access to the cabling via a door.
Step 4: Cutting the Channel
Step 5: Installing the Mantel Board
Set your mantel board on the mantel and trace the circles as a drilling guide on to the wall. I drilled 2 1/2" holes. Pic 2 shows the hole I drilled through the double stud on the left side of the fireplace. This hole was made with a 1 1/2" spade blade. Thankfully, the bit was long enough. Next, secure the mantel board to the wall using nails placed into the wall studs.
Step 6: Pulling the Cables
The magnets make short work of running the first string since you can guide the bolt & washers down the wall to your exit hole. The toughest part was passing the bolt & washers through the wood studs and placing them between the wood paneling and the insulation inside the wall. If you are working on an interior wall, this won't be a problem as only exterior walls are insulated. Overall, it wasn't very difficult to place and guide the string down to the exit hole near the floor.
Once you have your first string run, tie multiple strings to it and pull them back up to the mantel top. How many cables you plan to run will determine the number of strings to pull. In my case, I pulled 5 strings for 3 HDMI cables and one power cord. The 5th string will remain in the wall for future use.
Next, pull your cables one at a time. What worked well for me was to tie the string securely behind the plug and then cover the cable end with electrical tape. This helps the cable follow the string and eliminates any edges on the plug which might get hung up. Make sure you have your other strings secured so they do not get pulled along with the cable. It is a good idea to tape the extra strings to the mantel with packing tape. Pull all necessary cables and secure the remaining pull string in the wall for future use.
Hook up your TV and you're done! I hope this instructable was helpful and sparked some ideas for running cables above a fireplace.
Thanks for checking it out and I look forward to your comments and suggestions for improvement.