Floor cabling

October 25, 2007 8:21 AM

How do I run a cable under my floor?

Let me be a little more precise: How do I run a string from one hole, under 12 feet of floor, and then fish it out of a second hole on the other side? Once I have the string, I can then pull heavier cord, then my cables, etc.

I've been considering everything from fishing poles, powerful magnets, to mice and cheese.

If it is impossible w/o pulling up the floorboards or turning them into swiss cheese, then I will admit defeat and buy those raceways mentioned in previous AskMeFi posts.

Thanks for your help!

posted by cgs to home & garden (12 comments total)

What's under your floor? I mean, what's the structure made of?
posted by aramaic at 8:24 AM on October 25, 2007

Depends what is under the floor, if it's a concrete slab you are out of luck, if the joists are running perpendicular to the direction you are trying to go then again out of luck. If the joists are going parallel to where you want to go then you may be able to do it with a metal chain and a real strong magnet, or some of those bendy poles/fish tape you can get at Home Depot for just this purpose
posted by zeoslap at 8:26 AM on October 25, 2007

Here are some tools that may help
posted by zeoslap at 8:27 AM on October 25, 2007

Use an air compressor. Blow the air in one side, if there is no other place for the air to go, you can send a string to the other end. Progressively pull more secure cords through.
posted by enobeet at 8:27 AM on October 25, 2007

You need an electrician's snake. You can push this under the floor (assuming there are no barriers between the holes), then catch it at the other hole with another snake or just a coat hanger, and then pull your wire or string back from second hole to first.
posted by beagle at 8:29 AM on October 25, 2007

What beagle said, though I have always called it "fish tape".
posted by GuyZero at 8:40 AM on October 25, 2007

When I was doing this, I used 30 amp cable (the stuff you use for showers and cookers). It's stiff enough to get to the other end, but flexible enough that you can ram it down a hole behind the skirting board. Conduit can work for short runs, but doesn't bend.

But sometimes, there's no choice but to cut a trap or to get under there and pull the cable yourself. Small children are useful for this.
posted by Leon at 8:49 AM on October 25, 2007

Thirding the fish-tape with the caveats as listed by zeoslap above. The fish-tape is also useful for other things, like dragging dryer-vent brushes through long stretches of ductwork.
posted by jquinby at 9:01 AM on October 25, 2007

what about using a 20' tape measure with a piece of string tied to it?
posted by noloveforned at 9:51 AM on October 25, 2007

If the under-the-floor route doesn't work out and you have base and/or shoe molding over drywall, it's possible to run low-voltage wires behind the molding. You'll need to remove the it and possibly cut a channel in the wall. I had a contractor do this once when they had finished a room without properly installing all the wires that they should have. Whether it's worth the work in your situation is of course up to you.
posted by metric space at 9:58 AM on October 25, 2007

holy crap.... that fish-tape is perfect! there is space under the floor, and the joists are running my way, so i'm good to go.

noloveforned- i'll try your way first... i hadn't thought at all about my tape measure.

thanks everyone!
posted by cgs at 10:57 AM on October 25, 2007

Sometimes using the lid from a piece of square conduite can do the job, tape the cable to one end and bend the lid under the floor. It's rigid enough to pus most things out the way, and be able to be controlled as you push it through (unline solid core 30A cable) but bendy enough to go through.

http://www.networkcablingservices.co.uk/acatalog/standard_trunking.jpg


Also concider putting a "drawline" through as you place the cable, should you or someone else want to pull any other cables through. A bit of nylon string/rope will do it.
posted by ilumos at 4:48 PM on October 29, 2007