Tuesday, January 1, 2019

Drilling Walls

As mentioned in Residential Electricity 101 the basic idea of the Drilling step 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. 

Begin drilling when everything is nailed in place.  This will help prevent wasting time drilling unnecessary holes. A box might end up being mounted over the hole you just drilled.

When drilling be careful:
- Don't let the handle spin around and club you in the head.
- Don't allow long hair or a hoodie draw string get twisted up in the spinning bit and hurt you.
- Wear safety glasses to keep a hot chip off a nail from burning your eye. 
- Be sure there is nothing on the other side of the board you are drilling. Items like a wire or a plumbing pipe.

   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. 
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. 
 Keep your holes in the center of the stud 
 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 review the instructions your boss just gave you by asking,"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 ask, "Can't we use a GFI breaker and run the 12/2 directly to the hot tub?
   Boss, "Yes some companies do but we don't because GFI breakers cost $30 and GFI receptacles cost $10"

Knowing why something is done can help you remember how to wire different circuits.
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 on one side of your stud then you can drill your hole "off center" but 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.

Electricians like to use 17 inch long ship auger bits and high speed, heavy duty 1/2 inch drills

Nail Plates 
There will be times when you have to drill a hole close to the edge and not in the center of the stud. When this happens use a nail plate to protect your wire.

Nail plates are used to protect your wiring from screws and nails like those used to attach sheet rock and wood trim. The plates have sharp teeth that are hammered into the stud covering the spot where the wire is too close to the surface.

Drilling the walls.

This is the correct way to drill a wall. 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.

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 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.

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 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.

Some Drilling Tools
Locking Cord ends
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. 

Specialty Drill.

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 https://www.redtoolstore.com


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