Welcome back to our Basement Remodel Pro-Follow. I’ve been shadowing expert general contractor Joe Bianco and his crew as they finish an unfinished basement. This is the third installment in our series.

• Day 1 covered framing out the basement into four distinct rooms.
• Day 2 covered the plumbing rough-in, which included re-positioning an underground drain for the bathroom shower.

Today I’m covering the electric rough-in, following a subcontracted master electrician through a two-day process. We’ll be reviewing installation of a new sub-panel, recessed lights, receptacles, and more. Here’s a diagram of the plan for this space and a picture post-framing to refresh your memory on our progress to date.

Step 3: Plan the Electrical Rough-In & Obtain Permits

The day before the electrician began work, he came out and walked the floor with Joe and the homeowner. Together, they discussed the vision for the basement. As the homeowner and Joe described the basement’s individual functional areas, the electrician translated their discussion into electrical markings throughout the space, making recommendations to keep the basement in line with local codes. In this way, the homeowner and the contractor team came to a solid understanding of where all receptacles, recessed lights, cable connections, smoke detectors, and light switches would be placed, and where the sub-panel that would power the basement would be located.

In finished areas, code requires that outlets be spaced such that an outlet is reachable within 6′ horizontally of any place on an unbroken wall. This means that the maximum spacing for receptacles is every 12 feet; however, in practice, electrical outlets are often placed closer together for convenience. The code also specifies that Ground Fault Interrupters (GFI)-protected outlets must be used in all unfinished spaces, as well as in wet locations, such as the bathroom and wet bar.

Pro-Tip: Although not required by code, receptacles, switches and cable connections are typically placed 15″, 48″ and 62″, respectively off the ground.

SD indicates a smoke detector and R indicates recessed lights.

This electrical plan not only ensures the right expectations for the homeowner, it also allows the master electrician to obtain a permit for the job.

Step 4: Install the Electrical Components, Per the Rough-In Plan

Note that throughout the following steps, the electricians are fully cognizant of the plan for the space. Included in that plan is the installation of a sub-panel that will power the basement. Accordingly, as the crew runs cable to connect receptacles and cans, the source of any given circuit in this basement is the sub-panel, which itself will be tied into the main breaker panel in Step 4f.

Step 4a: Install boxes for Outlets, Switches, and Smoke Detectors

The next day, two electricians arrived and began by mounting boxes for outlets, switches and smoke detectors. Installing boxes first gives the electricians a solid understanding of which studs will need to be drilled to run Romex for the circuit.

As they worked, the team considered challenges with individual placements. For example, they added an extra 2×4 to move this box out from the corner, making it easier to hang drywall.

Pro-Tip: New code requires a neutral wire be located at every switch, because neutral is required for some newer dimmer switches to function. In the past, an electrician could run a 2-wire “switch cable” from an overhead lamp down to the switch. This cable would bring power down to the switch on the white wire, and take “switched power” back to the lamp on the black wire. (This could be remembered with the saying “white going down, black coming back.”). This switching strategy does not bring a neutral wire to the box. When the crew runs Romex for lights in this basement, the circuit will originate at the sub-panel and travel to the switch boxes first, before heading on to the lights, resulting in a neutral wire at both the switch and the lights.

Step 4b: Install Overhead Recessed Cans

The crew installed “new work”, IC (insulation contact) recessed cans, spacing them out evenly by measuring the area into thirds. For instance, in a 12 x 12′ space, four recessed lights are positioned in a square at 4′ intervals.

Pro-Talk: Recessed cans are rated IC (insulation contact) or Non-IC (no insulation contact) depending on whether the fixture can come in direct contact with insulation. Most Non-IC cans require a 6″ air gap between the can and the nearest insulation; whereas IC cans can have insulation packed tightly against them. IC cans are required in top-floor installations, but may be used in any installation.

Part of the electrical planning process focused on positioning switches along expected walkways. That means that as the homeowner enters a room, the switch is right where they’d expect it to be, and as they leave the room, they’ll never have to backtrack to turn off any lights. For instance, as they enter the basement, light switches are there to illuminate the large, entertaining area. These same lights can be turned off by another switch by the bedroom door. The electricians achieved this by running 3-wire between the two switches.

There are many articles already written that describe how to wire a three-way switch to accomplish this. Here’s a great one at The Home Improvement Web.

Pro-Talk: The term “2-wire” refers to a cable with a hot, neutral and ground wire within the wire sheathing. “3-wire” includes these wires an additional red wire called a traveler or signal wire, required in three-way switch configurations (where two switches control the same light), as well as in linked smoke detectors.

In this diagram of the entertainment area, the blue circles represent recessed lights, the green boxes indicate switches and the numbers denote the type of wire (2-wire or 3-wire) between them.

Step 4c: Drill Studs and Joists for Wiring

The crew used a 3/4″ auger bit to drill holes through the studs. While not required by code, most electricians will place these about waist height to avoid drywall screws.

Pro-Tip: Romex must be kept at least 1.25″ away from the nailing face. If wire is closer than 1.25″ to the nailing face, protective metal plates must be installed to ensure nails and screws will not penetrate the wire.

TJI joists are convenient for electricians because they feature knock-outs for running utilities, eliminating the need for drilling.

Step 4d: Run Romex Throughout the Basement

The electricians ran 14/2 (14 gauge, 2-wire) wire for most of the basement, securing the wires with insulated staples at 4′ intervals. Typically the crew put 8 to 10 receptacles on a circuit. The bathroom, wet-bar, refrigerator and microwave all receive dedicated circuits and are wired with 12/2 wire.

Additional Information: Below are the National Electric Code’s rules for wire gauges and over-current protection requirements. Note that I’ve simplified this explanation to keep it brief. There are actually more complex restrictions based on the distance the wire is being run and the type of wire being used. However, for most residential installations, the following applies.

• 14 gauge wire – 15 amps maximum – standard lighting and receptacle circuits
• 12 gauge wire – 20 amps maximum – appliance circuits
• 10 gauge wire – 30 amps maximum – water heaters, some HVAC equipment

The code generally allows for circuits to be loaded at 80%, meaning a standard 15-amp circuit can be loaded with 13 amps worth of fixtures and receptacles. The number of receptacles allowed on a circuit varies by district. Rather than specifying a limit for the number of receptacles on a circuit, the NEC uses a square-footage rating to determine the number of circuits required for a space. Generally, a safe assumption is that each receptacle will use 1.5 amps, which equates to eight receptacles per circuit for a standard 15 amp circuit. You should consult the NEC and your local code to determine the requirements for loading in your area.

Pro-Tip: Currently, the color of the sheathing indicates the wire gauge. White wire is 14 gauge, yellow wire is 12 gauge and orange wire is 10 gauge.

Smoke detectors must be wired with 3-wire so that if one alarm goes off, the others will too. The third wire serves as a signal wire between the individual detectors to synchronize their alarms.

It’s good practice to label wires to avoid confusion over which is which.

Step 4e: Tie in the Outlets, Cans, and Switches

After all the wires were in place and secured with staples, the electricians began to tie-in the boxes.

Pro-Tip: Several electricians I’ve spoken with all agree, the most common DIYer mistake is failing to properly twist wires before adding the wire-nut.

Pro-Talk: The term “tied-in” means ready for a receptacle or switch to be installed.

Notice how the white sheathing stops just after the wires enter the box. For spliced wires, the wires are stripped back evenly, twisted together, cut at 1/2″ length and then wire-nutted together.

Step 4f: Install the Sub-Panel

All of the new lights, receptacles and fixtures will be powered off a new sub-panel because the old panel didn’t have enough room.

To connect the two panels, the electricians ran #4 SER aluminum wire, which is capable of providing 60 amps of current. You may not be able to see them, but there are four wires within the gray sheathing: 2 hot, 1 neutral and 1 ground.

The new sub-panel is sized to fit between 16″ oc studs and held in place with screws.

All wires entering the sub-panel are secured with wire connectors.

The electricians use NOALOX, an anti-oxidant joint compound, for all the #4 SER terminations.

Pro-Tip: NOALOX is an oxidation inhibitor. When aluminum oxidizes, it becomes more electrically resistant. As this occurs, current flowing through the wires generates heat. Over time, oxidation can lead to a fire risk. Properly applying Noalox or another oxidation inhibitor to aluminum connections mitigates the risk of fire, and is required by code in most aluminum wiring applications.

Here’s what the panel looks like after some of the wiring has been partially completed. You can see the large, white-striped wire connecting to the neutral bar (left), the two red-striped wires providing power (center), and the ground wire is obscured behind other ground wires (right). This panel uses square-D breakers and provides 20 spaces.

Note that in sub-panels, the ground bus and neutral bus are separate. In the main panel for a house, ground and neutral are tied together on the same bus.

At the other end, the #4 SER connects to the existing panel with a double-breaker.

Pro-Tip: Avert your eyes when you flip the breaker to power the sub-panel for the first time. If there was an error, a bright flash may occur, temporarily blinding you.

Step 5: Electrical Rough In Inspection

The crew double-checked their work, tested a few connections, and will wait for the inspector to give the sign-off before making final connections at the main breaker panel.

Pro-Tip: In virtually every jurisdiction, permits and an electrical rough-in inspection are required prior to installing drywall. Failure to get a proper inspection may lead to the inspector later requiring that all drywall be removed. This can be extremely costly, so this step should never be skipped.

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