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BLD-ELEC05-05 · Lesson 12 · 39 clock hours · lab

Integrated Wiring Project: Plan, Build, and Inspect a Complete Rough-In and Trim-Out

Objective. Students will independently plan, rough-in, trim out, and submit for mock inspection a complete wiring installation—including panel, branch circuits, devices, and luminaires—for a supplied residential/light-commercial floor plan, demonstrating integrated mastery of all course skills.

Integrated Wiring Project: Plan, Build, and Inspect a Complete Rough-In and Trim-Out

This lab brings together every skill you have developed in Residential and Commercial Wiring. You will act as the electrician of record for a mock installation: planning the work on paper, executing rough-in and trim-out on a physical mock-up, and defending your installation to a mock inspector. Mastery here means you can perform—and explain—every step without prompting.

Phase 1: Planning Before You Touch Any Material

Professional electricians plan before they pull a single wire. Your plan package must be approved before rough-in begins. It consists of four documents:

Circuit layout drawing. Mark every outlet, switch, luminaire, and special appliance on the supplied floor plan. Show the home run for each circuit and label the circuit number. Use standard electrical symbols so any qualified reader can follow the drawing.

Panel schedule. List every circuit by number, describe the load it serves, record the breaker amperage and pole count, and note the wire gauge. The schedule must match your layout drawing exactly.

Box fill calculation sheet. For every box on the plan, calculate conductor fill per the NEC using the volume allowance method. Count conductors, devices, and clamps correctly, and verify that each box has sufficient cubic-inch capacity. An overfilled box is a code violation and a real fire hazard.

Load calculation. Compute the total calculated load for the dwelling or space. Apply the demand factors the NEC allows for general lighting, small-appliance circuits, laundry circuits, and large appliances. Verify that the panel's main breaker and service entrance conductors are sized to serve that load. Your calculated result must be within ±5% of the instructor's answer key.

Review your plan against the NEC before submitting. Once the instructor approves, any change to the plan must be re-approved.

Phase 2: Rough-In

Rough-in is the work done before walls are closed: mounting boxes, running cable or conduit, and landing conductors at the panel. Work from your approved plan.

Box mounting. Set outlet boxes at the correct height for the installation type (residential versus commercial), nail or screw them securely, and orient them so the face will be flush with the finished wall surface. Mark stud faces or concrete with a permanent marker so the inspector can find each box.

Cable and conduit installation. Where NM-B cable is permitted, staple it within the required distance of each box and at the NEC-specified intervals along the run. Where EMT is required (exposed wiring in commercial or garage areas, for example), cut conduit squarely, ream all ends, and make up watertight connections. Support EMT at the intervals the NEC specifies.

Panel landing. Strip conductors only to the manufacturer's listed strip length. Land each circuit conductor under the correct breaker, torque terminal screws to the manufacturer's specification using a calibrated torque screwdriver or torque-indicating bit, and dress conductors neatly inside the enclosure. Neutral and equipment grounding conductors must land on the correct bus bars for the panel type (main panel versus sub-panel).

Safety during rough-in. The panel must be de-energized and locked out/tagged out any time you are landing conductors. Confirm absence of voltage with a calibrated non-contact tester before touching any terminal. Wear safety glasses when drilling and cutting. Keep the work area clear of cords and scrap to prevent trips and falls.

Phase 3: Trim-Out

Trim-out is the finish work after walls are closed: installing devices, luminaires, the panel cover, and the circuit directory.

Install receptacles with the correct orientation, torque the terminal screws, fold conductors carefully into the box, and secure the device so it is flush and level. Install switches with the toggle in the correct position for the circuit function. Install luminaires per the manufacturer's instructions; confirm that the box is rated for the fixture weight before hanging any luminaire heavier than 35 lb (or 50 lb if the box is listed for that load).

On the panel, install the cover, ensure all unused knockouts are filled, and complete the circuit directory in permanent ink. A panel with a missing cover or blank directory is an automatic deficiency.

Phase 4: The Mock Inspection

The inspector will work through a standard residential/commercial electrical inspection checklist. They may ask you to cite the NEC section that governs any element of your installation. You must answer confidently or look up the answer in your code book—using the NEC during inspection is not only allowed, it is professional practice.

If a deficiency is noted, correct it on the spot. The inspection is not complete until the checklist shows zero unresolved items and the inspector signs off.

Daily work log. Throughout all phases, record what you did each session, what materials you used, and any problem you encountered and how you resolved it. The log is part of your grade and demonstrates the habit of documentation that employers and licensing boards expect.

Safety Summary

Key terms10

Rough-inThe phase of electrical installation completed before walls are closed, including mounting boxes, running cable or conduit, and landing conductors at the panel.
Trim-outThe finish phase of electrical installation completed after walls are closed, including installing devices, luminaires, the panel cover, and the circuit directory.
Box fill calculationAn NEC-required calculation that uses cubic-inch volume allowances to verify that all conductors, devices, and clamps will fit safely inside an electrical box without overcrowding.
Panel scheduleA table, mounted inside or on the panel cover, that lists each circuit by number, its load description, breaker amperage, pole count, and conductor size.
Load calculationA step-by-step arithmetic process using NEC methods to determine the total electrical demand a building places on its service, used to verify that conductors and overcurrent protection are correctly sized.
Demand factorAn NEC-permitted multiplier applied to certain load categories (such as general lighting or appliances) that reduces the calculated load to reflect that not all loads operate simultaneously at full rated power.
Torque specificationThe manufacturer-listed tightening force, expressed in inch-pounds or foot-pounds, that must be applied to terminal screws to ensure a safe, code-compliant electrical connection.
Lockout/tagout (LOTO)An OSHA-required procedure in which energy sources are isolated and physically locked in the off position, and a tag is applied, before any work on electrical equipment begins, preventing accidental re-energization.
Home runThe cable or conduit segment that runs from the first device or box on a branch circuit directly back to the panel, where it connects to the overcurrent protective device.
Circuit directoryThe permanent, legible label inside or on a panel cover that identifies the load or location served by each circuit, required by the NEC to be completed before a panel is placed in service.

Worked examples4

1. Box fill calculation for a single-gang device box containing: 3 × 14 AWG circuit conductors (two hots, one neutral), 1 × 14 AWG equipment grounding conductor (EGC), and 1 duplex receptacle. The box is stamped 18 in³. Is it legal?
  1. Step 1 – Determine the volume allowance per conductor for 14 AWG. The NEC assigns 2.0 in³ per 14 AWG conductor.
  2. Step 2 – Count conductors: 3 circuit conductors = 3 × 2.0 = 6.0 in³.
  3. Step 3 – Count EGCs: all EGCs together count as ONE conductor = 1 × 2.0 = 2.0 in³.
  4. Step 4 – Count devices: each single device (yoke) counts as TWO conductors = 2 × 2.0 = 4.0 in³.
  5. Step 5 – Cable clamps internal to the box count as ONE conductor total if present; none are stated here, so clamp allowance = 0.
  6. Step 6 – Total fill = 6.0 + 2.0 + 4.0 = 12.0 in³.
  7. Step 7 – Compare to box capacity: 12.0 in³ required vs. 18 in³ available. 12.0 ≤ 18, so the box is legal.
Answer: Total fill = 12.0 in³; the 18 in³ box has adequate capacity. Installation is code-compliant.
2. A 1,200 ft² residential dwelling (no basement, no garage) has the standard small-appliance and laundry circuits. Calculate the general lighting and receptacle load and the small-appliance and laundry load before demand factors, then apply the NEC demand factors to find the net calculated load for those categories.
  1. Step 1 – General lighting load: 1,200 ft² × 3 VA/ft² = 3,600 VA.
  2. Step 2 – Small-appliance circuits: the NEC requires a minimum of two 20-ampere small-appliance circuits at 1,500 VA each = 2 × 1,500 = 3,000 VA.
  3. Step 3 – Laundry circuit: the NEC requires at least one 20-ampere laundry circuit = 1,500 VA.
  4. Step 4 – Sum before demand factors: 3,600 + 3,000 + 1,500 = 8,100 VA.
  5. Step 5 – Apply NEC demand factors for this load category: First 3,000 VA at 100% = 3,000 VA; remainder = 8,100 − 3,000 = 5,100 VA at 35% = 1,785 VA.
  6. Step 6 – Net calculated load for these categories = 3,000 + 1,785 = 4,785 VA.
Answer: Net calculated load for general lighting, small-appliance, and laundry categories = 4,785 VA after NEC demand factors.
3. You are bending a 90° stub-up in ½-inch EMT for a box that must sit 12 inches above the floor. The bender shoe has a take-up (shrink) of 5 inches for ½-inch EMT. Where do you place the bender mark on the conduit?
  1. Step 1 – Identify the desired finished stub height: 12 inches.
  2. Step 2 – Subtract the bender take-up from the desired height: 12 − 5 = 7 inches.
  3. Step 3 – Measure 7 inches from the end of the conduit and place your mark there.
  4. Step 4 – Align the arrow mark on the bender shoe with the mark on the conduit, then bend to 90°.
  5. Step 5 – After bending, the stub should measure 12 inches from the end to the back of the bend.
Answer: Place the bender mark 7 inches from the end of the conduit. After bending, the finished stub measures 12 inches.
4. A 120/240 V single-phase residential service has a total calculated load of 24,000 VA. What is the minimum ampacity required for the service entrance conductors, and what standard breaker size would you select?
  1. Step 1 – Use the formula: Current (A) = VA ÷ Volts. For a 240 V single-phase service: I = 24,000 ÷ 240 = 100 A.
  2. Step 2 – The conductors must have an ampacity of at least 100 A.
  3. Step 3 – The NEC requires a minimum 100-ampere service for a single-family dwelling. 100 A satisfies both the calculated load and the minimum service size requirement.
  4. Step 4 – Select a standard 100 A main breaker (the next standard size at or above the calculated 100 A).
Answer: Minimum required ampacity is 100 A; select a 100 A main breaker and service entrance conductors rated at least 100 A.

The math in this lesson2

Learners compute box fill, a 1,200 sq ft dwelling load, a stub-up mark using take-up, and service amperes from 24,000 VA.
N-Q.1G-GMD.3
Brush up in the math halls at newSchoolWorks.com:
In class: Given a supplied floor plan, students produce a circuit layout drawing, panel schedule, box fill calculation sheet, and load calculation before touching any materials; instructor reviews and approves the plan package before rough-in begins. · Students execute rough-in (cable or EMT as applicable to each area, box mounting, panel landing) and trim-out (devices, luminaires, panel cover and directory) on their assigned mock-up section over multiple lab sessions, maintaining a daily work log. · Final mock inspection: a second instructor or industry guest acts as the inspector using a standard residential/commercial electrical inspection checklist; students must answer questions about their installation (citing NEC sections) and correct any noted deficiencies on the spot.
Materials: Assigned floor plan and panel schedule template, full tool kit (drills, fish tape, conduit benders, hand tools), NM-B and EMT materials, load center, breakers, devices, luminaires, NEC current edition, box fill and load calculation worksheets, daily work log, inspection checklist
Check: Mock inspection checklist: zero unresolved deficiencies after corrections; plan package complete and accurate (load calc within ±5%, all box fills correct); daily work log complete; inspector sign-off required to pass.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

NCCER Electrical – Planning and Layout
1. Before any rough-in work begins on your integrated project, which set of documents must be completed and instructor-approved?
NCCER Electrical – Box Fill and Raceway Fill
2. When performing a box fill calculation for a single-gang box containing 12 AWG conductors, the NEC volume allowance per 12 AWG conductor is:
OSHA 10 – Electrical Safety / Lockout/Tagout
3. You are landing conductors inside an energized-adjacent panel enclosure. What is the FIRST action required before touching any terminal?
NCCER Electrical – Box Fill Calculations
4. A device box is stamped 18 in³. It contains two 14 AWG circuit conductors, one 14 AWG EGC, and one single-pole switch (one device yoke). Internal cable clamps add one additional conductor allowance. Is the box legal, and why?
NCCER Electrical – Panel Installation and NEC Compliance
5. During trim-out, which condition would cause an automatic deficiency on the mock inspection checklist?
NCCER Electrical – Load Calculations
6. The NEC general lighting demand factor calculation for a single-family dwelling applies 100% to the first 3,000 VA and what percentage to the remainder?
NCCER Electrical – Branch Circuit Sizing / NEC
7. During the mock inspection, the inspector asks you to justify the wire gauge you used for a 20-ampere small-appliance circuit. The correct minimum conductor size for a 20-ampere, 120-volt branch circuit using copper conductors is:
State Journeyman Electrician – Professional Practice
8. What is the primary purpose of maintaining a daily work log throughout the integrated project?
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