Welcome to DIY skill set 2. Before we get started with the task at hand, wiring our new walls for switches and duplex receptacles, I want to spend a moment talking about electrical codes. The NEC (National Electric Codes) provides the bare minimal requirements that an electrical installation must meet in order to be safe. Almost every area has its own local electric codes which may present requirements more stringent than those of the NEC so it’s essential that every electrician, whether professional or DIY, needs to be familiar with both codes. You need to have copies of both on hand to refer to as you work and as you prepare the documents needed when applying for a building permit.
Tools that you will need
· 16oz claw hammer
· Tape measure
· Ideal Electrician’s Tool pouch
· 3/8” Drill/driver
· Set of spade bits ¼” to 1 1/4”
· Klein 8” High-leverage Lineman pliers
· Klein 8” High-leverage Diagonal Pliers
· Klein 7-piece screwdriver set
These are professional grade tools and may seem expensive but quality tools are not only a joy to work with but they will last you a life time with the proper care. In the long haul cheaper tools actually cost more because you have to keep replacing them.
Supplies that you will need
· Plastic Scotch 88 electrical tape
· Ideal Yellow Wing-Nuts wire connectors
· Ideal Red Wing-Nuts wire connectors
· Ideal Green Wing-Nuts wire connectors
· Carlon single gang, 18 cu. In., blue nonmetallic switch and outlet boxes
For this tutorial we will be working with NM (Nonmetallic-Sheathed) Cable as covered under Article 334 of the NEC. This is the most common wiring system used in homes today although some local codes may require the use AC (Armored Cable) or another wiring method. Nonmetallic-Sheathed cable comes in three basic types. Type NM cable that the codes permits to be used for both exposed and concealed wiring in normally dry locations (NEC 334.10 (A)). Type NMC cable that has a corrosive resistant jacket that is allowed to be used in dry, damp, wet and corrosive locations except where specifically prohibited by code (NEC 334.10(B) and 334.12(A)(B)). Ok, let’s get started roughing in the electrical for our new wall(s).
There isn’t anything in the code that specifies the height of duplex receptacles as measured from the finished floor but the commonly accepted height is between 14” to 16” to the top of the device box. The commonly accepted height for switches is between 42” to 45” to the top of the device box. For aesthetic purpose mount them at the same height as the existing receptacles and switches. On the other hand, the Code has a great deal to say about the number of receptacle required and where they are located. Based on Article 210.52 of the NEC
· Any wall space 24” or greater in width requires a receptacle
· No point along the floor line measured horizontally in any wall space may be more than 6 feet from a receptacle. The easiest way to comply with these requirements is to start measuring at the corner of an opening and place the first receptacle six feet from that point. After that each duplex receptacle can be placed at 6 feet intervals because each half of the double receptacle covers a span of 6 feet in each direction.
· If you are installing receptacles in a new wall that runs perpendicular to an existing wall the best place to start measuring is from the nearest receptacle in the existing wall. Depending on the distance of the last existing receptacle from the point where the new wall intersects the existing wall you may have to install a new receptacle in the existing wall to keep the spacing within Code requirements.
· I’ll cover adding new receptacles to an existing finished wall in another Skill Set. For this tutorial we will assume that the point where the new wall intersects the existing wall is 6 feet or less from an existing outlet allowing you to position the first outlet in the new wall 12 feet from the last outlet in the existing wall.
With that said layout the locations of the new receptacles. Mark the spots on the studs for the device boxes using a Sharpy™. And mount the ABS device boxes to the studs. There are a couple points regarding how the boxes shall be mounted according to the NEC Article 314.21 The boxes must be mounted so that the front lip of the box must not set back further than ¼” from the surface of the finished wall
With the boxes mounted we are ready to start drilling the studs to run the Romex™. These holes must be positioned and drilled according to Code or your job will fail the rough-in inspection. All holes must be drilled so that the edge of the hole is no less than 1 ¼” from the nearest edge of the framing member NEC 300.4(A)(1). When wiring a partition wall this means that you have to drill your ¾” holes dead center to meet Code. If this distance can’t be maintained you have to install 1/16” thick steel guard plates to protect the cable per NEC 300.4(A)(1)(2). The reasons for these requirements are required to prevent the cable from being damaged by a stray screw or nail.
Supporting the cable. The NEC requires that NM cable be supported within 12” of every device box and at 4 ½ foot intervals thereafter per Article 334.30. When using Romex staples to secure the cable they should be used in such a manner as to not damage the cables jacket and/or the conductors inside the jacket. Where the cable enters a device box the cable jacket should extend ¼” beyond the box clamp and there should be a minimum of 6” of free conductor extending into the box per Article 300.14.
Coming up in Skill Set 3 we will cover selecting devices like duplex receptacles and switches and what their specifications means. We will also cover basic switch and receptacle circuits.
