Check the whole wall cavity with a stud finder A decent stud finder is a must-have for every wire-fishing job, but don't throw it back in your pouch after you've located the studs. Use your stud finder to check the whole wall cavity for obstacles like blocking and abandoned headers. You don't want to find out the hard way that you should have fished your wire one stud cavity to the left or right.
The tools you need
Flex bits and glow rods are the go-to tools Tim uses to fish wires. Flex bits are great for drilling holes in hard-to-reach spaces (see "Invest in a Bumper Ball." p.102). The two most common lengths are 5 ft. and 6 ft., but extensions are also available. A 3/4-in. x 54-in, flex bit costs about $50 at home centers. Buy a bit that has a hole on the end of it so you can use the bit itself to pull wires (more on that later).
Once your hole is drilled, you can shove a glow rod through the hole, attach your wire to the eyelet at the end and pull it back through. Glow rods can also be used to hook wires to pull them out. As their name suggests, glow rods glow in the dark. This makes them easier to spot when you're working in dark areas (which is most of the time).
Glow rods come in various lengths and thicknesses, and you can combine as many sections as the job requires. Thinner rods flex more and work better when you have to make sharp turns. A thicker rod can span longer distances and is better for hooking wires that are more than a few feet away. A 9-ft. glow rod kit costs about $38 at home centers. Expect to pay about $60 for a 24-ft. kit.
Push through more than you need When hooking a wire to pull it toward you, make sure there's more than enough wire to hook on to. Sometimes it's a real challenge to grab hold of a wire, and once you have it hooked, you don't want to lose it. Tim always makes sure that he has at least 5 or 6 ft. of extra wire to keep up the tension on the hook the whole time he's pulling on it.
SEAL THE HOLES
If you're drilling holes through top and bottom plates or running wires through a fire wall in the garage, you must seal those holes with a fire-resistant caulk or foam sealant to comply with fire and energy codes. Most building officials won't make you bust out large holes in ceilings and walls in order to access hard-to-reach holes, but check with your local official before you begin your project. A can of fire-blocking insulated foam sealant costs about $10 at home centers and hardware stores.
Don't spin apart the glow rods
Sometimes you need to twist and spin glow rods in order to snake them past ductwork, pipes and other obstructions. A great way to lose a rod or attachment in a wall or joist space is to twist it so many times in the same direction that it unthreads and comes apart. Some pros wrap a little electrical tape around the connections to keep them secure.
HOOK ON TO A FLEX BIT
Sometimes you don't need to use glow rods at all. Most flex bits have holes in the ends of them. If you have access to where the flex bit pops out, attach your wire directly to the bit and fish the wire through that way. Tim twists the wire and tapes it up to make sure it doesn't come off when he's pulling it back through (see "Hold On Tight," p.102). Remove your bit from your drill before pulling so you don't accidentally spin the bit and twist up your wire.
Protect drywall with a mud ring
Mud rings, also called drywall brackets or low-voltage "old-work" brackets, are great for protecting the drywall when you're drilling with a flex bit or cranking on a glow rod. They're easy to install (just tighten two screws) and cost less than $2 at home centers. Once the wires are connected, you can screw the wall plate to the mud ring.
Mud rings are approved only for low-voltage wires like communication and coaxial cables. If you need to install a regular gang box for an electrical receptacle or wall switch, install the mud ring temporarily to protect the drywall while you fish the wire, then remove it.
Fish wires through the holes for recessed lights When you're installing new recessed can lighting, fishing wires from one light to another is easy because you have a great big hole to pull the wires through. But even if you're not installing new lighting, you can use the existing openings. Many cans can be easily popped out of the opening by removing a few screws.
INSTALL CONDUIT INSIDE CABINETS
Additional outlets above the counter space--that's one of the most popular electrical retrofits. Tim loves these jobs because he just fishes his wire through a flexible conduit installed right through the base cabinets. If you drill the holes for the conduit as far back and as high as you can, no one will ever notice.
Invest in a Bumper Ball Wires aren't supposed to be installed any closer than 1-1/4 in. from a penetrable surface (the outside of the drywall). That means you shouldn't be drilling holes right next to the drywall. But it's not always easy to control where a flex bit goes. A Bumper Ball flexible drill bit guide installed on the end of your flex bit will help maintain the proper space between the bit and the outside of the wall cavity. You can buy a set of two at electrical suppliers or at licensedelectrician.com for $13.
Hold on tight When Tim hooks cable to the eyelet of a glow rod, he strips the plastic sheathing back about 6 in., then cuts off the hot and neutral wires. He then wraps the remaining ground wire through the rod's eyelet and wraps it back around the wire's sheathing several times. Finally, he wraps the whole area with electrical tape.
When hooking coaxial cable, Tim just tapes the whole wire to the glow rod. He's never lost a wire just using tape.
Tim uses the same technique when working with communication cable like phone wire. If you try to hook one of the small communication wires, you could stretch and damage that individual wire several feet down inside the sheathing.
Get a better view with an inspection mirror You know your wire is in there somewhere, but you just can't seem to find it. It's probably hung up on another wire or pipe, but guessing isn't going to solve the problem. Tim shines a flashlight onto an inspection mirror to find out exactly what's going on. This is a simple, inexpensive tip that can save you a lot of time and frustration. Pick up an inspection mirror at an auto parts store for less than $10. Or bump it up a notch and pay a few more bucks for a mirror with small built-in lights, so you can see exactly what's going on.
DON'T SPIN THE BIT IN INSULATION
The best advice for fishing wires through insulation is "Avoid it if you can." The potential is always there to damage the vapor barrier or bunch up insulation, leaving cold spots in the wall. If you must fish wires through exterior walls, the best tip is to avoid spinning the flex bit until you make solid contact with the wood you plan to drill through. If you drill too early. you'll end up creating a large insulation cotton candy cone, which will make retrieving your bit difficult, if not impossible.
Keep low-voltage wires away from electrical cables
It's really tempting to fish low-voltage wires (like coax and Cat-5e) through existing holes occupied by electrical cables, but don't do it! Even though cables are insulated, the high-voltage current can interfere with the signal in the low-voltage wires. This could result in bad TV reception or unreliable phone and Internet service. Drill a new hole, and keep the new low-voltage wire several inches away from electrical cables. It's OK to run low-voltage wires perpendicular to cables, and it's also OK to run low-voltage wires next to electrical wires that are encased in conduit or metal sheathing.
BUY EXTRA WIRE
Have plenty of extra wire or cable on hand, because it's not likely that you'll be able to fish a wire in a straight line from Point A to Point B. There's also the possibility that your wire might get hung up on something, and you'd have to abandon it and start over.
MEET THE EXPERT
Tim Johnson works for Norske Electric in Savage, MN. He became an electrician 15 years ago after finishing a stint with the U.S. Navy. He works 714, on both commercial and residential projects, and even spent a couple of years wiring up wind turbines 265 ft. in the air!
BY MARK PETERSEN firstname.lastname@example.org