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What's behind that wall?Sunday, March 02, 2008
With most of a day to spend working on the house, I decided to tackle the electrical system to figure out exactly how we're going to install this new (well, okay, it's not so new - it's the one that used to be in the office) ceiling fan.

First task: gain access to the back of the attic. This had been quite a mystery when we toured the home - why was there a wall sealing off the back half of the attic? And even more mysterious - what might be back there? It was time to find out! After a few minutes spent trying to remove all the screws from one of the sheets of drywall, the a few minutes spent prying and pulling, the right-most section was free and I found, well, a bit of a mess.

Fortunately, there's a nice power junction box up here that I might be able to use for our current project - this is where they must have run all the wiring when they redid the third-floor bathroom and the guest room.

After a little clean up, we found a number of moderately interesting things, include a radio shack catalog from the early eighties, a number of bricks, and a rather large rock (why was this in the attic?)

With clear access from above, I decided to try to locate the center of the ceiling and drill a hole up through... I'd been searching down in the basement for some string that I could run from corner to corner, but was coming up empty. Then I saw the fancy little laser level that we bought a few months back... it's got a tripod and leveling screws under a laser head which spins fast enough to create a nice solid line. Though it's meant for indicating horizontal likes for tile and such, I turned the head sideways and it make a nice crisp line across the ceiling!

Doing this on each diagonal, I was able to find a point that seems quite close to the middle of the room. After drilling a small hole, I stuck a short section of electrical cable up through the hole, then ran upstairs to find the other end...

It came up right under the little walkway, but that shouldn't be a problem.

The next task was to figure out exactly how the old system was wired and lay out how we'll run the new system. One thing we've known for a long time is that the outlets in the room were controlled by the switch, and this is something we definitely wanted to undo. Turning off circuit #1 and pulling out the switch, I found just two wires, one running up and one running down...

That's the good old knob and tube wiring - they didn't bother switching the neutral wire, just the hot side (well, in theory they always switched the hot side!) Moving back up to the attic, I measured out the distance to the spot above the switch and started digging through the insulation to find that wire coming up through the ceiling...

After a bit of tracing, I realized that this is running to the outlet on the back wall. Back downstairs, I opened up that outlet, and found that it had four wires running into it, one from above, and three from below... here's a sketch of my best guess of how it's laid out:

It seems that the outlet on the back is serving as a bit of a junction for the wires which then run on to the outlet on the left wall. Now, how to modify things? Realizing that circuit 1 is one of the original circuits in the house and that it's rather overloaded, I wanted to switch over to either circuit 8 or 9 (the two circuits in the junction box we saw earlier). We also wanted to run two wires so that we could control the light and fan independently. Here's the plan...

It's a bit of a mess, but it's going to accomplish everything we were hoping for (it does require running new wire down to the switch and the far-wall outlet, but that "shouldn't" be too hard since there are already holes from the old hot wires). To put this plan to the test, we started with the task of running the new 3-conductor down from the attic to the switch...

and now we've got the fancy new switch installed! (though all it's going to is a coil of wire in the attic :-)

Hopefully I'll have the time over the next few days to wrap up the major electrical work and then it'll be back to the un-painting...

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