Drilling Walls For Electrical Wiring

· Residential Electricity 102

How to Drill Walls

As mentioned in Residential Electricity 101 the basic idea of the Drilling step of an Electrical Rough In, is to provide a pathway for all the wiring that you will be running throughout the house.
Not only electrical wires but also low voltage wiring for door bells, garage doors, phone and TV coax.
The key points we learned;
> Keep your holes in the center of the stud
> Drill as many holes as possible without drilling any unnecessary holes.

 > The more holes (necessary holes) that are drilled before pulling wire, the less risk there is of accidentally drilling through a wire.   
 > Keep your holes in the center of the stud
 > Try to drill your holes level with each other, the same height off the floor. It doesn’t have to be exact, just somewhat level.
 > Avoid the area where wood trim is nailed so the nails don’t hit your wiring;   Trim is nailed close to the floor and close to windows and doors.
 > Avoid the mounting screws of upper and lower kitchen cabinets by drilling your holes across the back splash area of the kitchen counter.
 > And in case you missed it,  Keep your holes in the center of the stud! 
   If you did miss it; that this was mentioned 2 times before, you need to pay closer attention. 
When electrical apprentices don’t absorb or clarify instructions they end up getting shocked or hurting someone else.  Pay attention, listen closely. To clarify instructions you can ask questions about the instructions or repeat the instructions back to your boss;  
   You ask,”OK So you want me to run a 14/2 home run from the panel up to the attic, across the attic and down to the hot tub, right?” 
    Boss, “Yes but use 12/2 not 14 and run it down to a GFI receptacle in the closet first, then to the hot tub.”
   You “Can’t you use a GFI breaker and run the 12/2 directly to the hot tub?
This nail plate is used to protect the wire
from screws and nails like those used to
attach sheet rock and wood trim.
Nail plates are attached to the stud where
the wire is too close to the surface. 

   Boss, ” GFI breakers cost $30 and GFI receptacles cost $10″   
   Knowing why something is done can help you remember to do it.  So why should we drill our holes in the center of the stud?  Because the closer the hole is to the nailing edge of the stud the greater the risk of a sheet rock screw or a trim nail penetrating your wire.  If there is a concrete basement wall one one side of your stud then you can drill your hole off center closer to the concrete where nails cannot enter the stud. The idea is not as much about “center” as it is to be as far away from nailing surface as possible. The code requires a nail plate to  be nailed on the stud by your wire if the hole is too close to the nailing surface. Nail plates are an extra cost taking extra time. Apprentices that use less material in less time and don’t fail an electrical inspection, are worth more dollars per hour. 
   There will be times when you cannot drill your holes in the center of the stud, when it happens use a nail plate to protect your wire.

Drill with a close angle

   Keep your drill close to the wall and pointing in the right direction.
Stay in the center of the stud and watch out for nails. If you hit a nail, pull the bit out and start a new hole nearby.

   This drill is pointing in the wrong direction. The angle off the wall is too large.  The holes in the 2nd, 3rd and 4th stud will not be in the center of the stud. This bit will not make it to the box but will end up out in the back yard.

Avoid “Built in” Ironing boards

   Because “built in” ironing boards (built into and flush with the wall) are not set in place during the electrical rough in, the wiring passing through the holes you drilled along the wall can interfere with the installation of the ironing unit. Check to see if the house will have a “built in” and mark the pocket location on the sole plate down at the floor. Any holes drilled at this pocket will need to be above or below the ironing board. 
   Notice in the photos below how the wire coming from the left is dropped down below the receptacle height to avoid the unit. Some “built in” ironing boards require a receptacle on the wall near the unit others require direct wiring to the top of the unit to power a light and a receptacle that turns on and off with a timer. In this example, we did both a receptacle below and a direct wire to the unit coming out of the same receptacle. This wire runs straight up the stud with the outlet and enters the ironing board pocket high above the unit. The wire is stapled loosely inside the pocket so that it can be easily removed when the sheet rock is cut out. 

An installed built in ironing board after sheet rock.
Notice how the unit is set deep into the wall
With most units the board unfolds straight down.
This unit also pivots to align with the wall.
A wall where a built in ironing board will be
installed in the 3rd pocket from the left. Holes
entering this pocket are drilled below receptacle
height and about 7 feet high to avoid the unit.

How to drill up through the top plate

   Make sure there is no wires or pipes hiding on top of the wall. Wear safety glasses or at least look down and away to prevent hot metal fragments (nails) and sawdust from entering your eyes. Look for signs of nails coming through and avoid drilling them.  Start your hole in the center of the top plate. Rest the handle on the stud, as shown, so that it doesn’t spin around and hit you in the head. Keep the drill pointing straight up and begin drilling.

How to Drill Corners

Drill at a 45 degree angle

   With 2 inch by 6 inch studs you can hold your drill at a 45 degree angle and drill a hole through a corner. If the hole, at the inner corner,  gets within 1 1/2 inch of the nailing surface you may have to use nail plates to protect your wire from the screws used to mount the sheet rock.
  There are times when I have gone outside and drilled into the rough plywood siding to get a good angle on a tight corner. In this photo⇒
I’m in another room, not outside.

Drill an Access Hole

   Sometime corners are framed in a way that allows no access to the space within the corner. 
When this happens, drill an extra hole so you can see into the blind spot and guide your wire through the holes.
The handle on this drill, and others, can be unscrewed and moved to the other side for left handed operation. 
  A side note, these blind spots are often not insulated, if you are building a house you might want to drill more of these holes and spray some expanding insulating foam into these hidden corners for better energy savings.

Drilling wooden I-beams

  Wooden I beams normally come with pre-punched knock out holes that can be removed by hitting the knock out with your hammer. If you have to drill through an I beam, stay in the thin center section not the wide upper and lower supports. Drilling through the supports will weaken the beam and require reinforcement or replacement. Always check the other side for plumbing or wires before drilling. 

   When your bit passes through these beams the thin panel will get caught in the groove of your drill bit and pull you forward, sharply. Prepare yourself for this pulling force so you don’t fall off your ladder. To prevent it, try to drill straight and push the drill real easy just before it passes through. 
   Also notice how a staple can pass through the thin center panel into your wires on the other side. 
Look before you staple and look before you drill.

Drilling above panels

Many wires will pass through the top plate above the electrical panels. Several holes will need to be drilled.

Some electricians like to drill one large 2” hole above the panel for all the home runs (a wire that feeds power from the panel to a circuit) but this is not recommended. The code has limits on how many conductors (wires) can be packed together as they pass through a hole because of the heat and resistance created by the magnetic fields that encompass a conductor. Also a large hole in the top of a wall can weaken the strength of the wall, for these 2 reasons it is best to drill several holes across the top plate above the panels. 5 x 1 inch holes is a good average for a 20 space panel and about 10 x 1 inch holes above a 40 space panel.
   First drill the large hole for the service wires then drill the 1 inch holes. When all the drilling and wiring is complete, you should have at least one empty hole for future wires. 
It is better to have too many holes above a panel than too few. You never want to have to drill a hole next to several wires especially if they are hot.

Some Drilling Tools

   When working your way through out a house drilling the framing, it is easy for the extension cord to get hung up on something and become unplugged. Some electricians will tie the connection into a big knot but this still gets hung up. This Qwiklok product locks on to your drill cord by pulling back on the At one time, we offered these colors - they are all identical and were used for ID and cosmetic reasonsyellow section as you insert the plug. When you release the yellow grip your drill cord is locked to the extention cord. It works great for drilling a rough in. You have to cut the female end off of your extention cord and attach the Qwiklok to your cord.

Insert a 17 inch drill bit into this extension to drill
out the tops of tall walls without a ladder. Or you
 can  insert a short 5 inch bit to equal the more
 expensive 17 inch bit and save money when 
the bit has to be replaced.
photo courtesy www.idealindustries.com 

Ideal’s 17 inch auger bit with 2 cutting blades
Photo courtesy www.idealindustries.com  

You either love it or hate it, this 33 Degree Angle Extension Drill by Milwaukee will allow you to drill across the ceiling joists without the use of a ladder. If you have a lot of ceiling joists to drill, you’ll love this model but get the one with a power cord. Drilling out a new house requires a lot of electrical power that will
cause excessive drain on battery packs like the one shown here. Photo by 

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