Chapter 13 Exercises

These exercises build practical panel knowledge — from identifying what's in your panel to calculating load and evaluating upgrade options. All exercises are safe for homeowners: panel door open, cover on.

Exercise 1: Identify Your Panel

Objective: Locate, identify, and characterize your home's main electrical panel.

Safety note: Open the panel door. Keep the panel cover (the metal plate over the wiring) on at all times.

Instructions:

Locate your main electrical panel and open the door. Record the following:

  1. Manufacturer name: (Printed on the panel — Siemens, Square D, Eaton/Cutler-Hammer, Leviton, GE, Murray, etc.)
  2. Main breaker amperage: (Usually printed on the main breaker itself — 100A, 150A, 200A)
  3. Panel amperage rating: (May differ from main breaker; printed on a label inside)
  4. Number of breaker spaces: (Count all slots, including those with no breaker installed — typically 20, 24, 30, or 40 spaces)
  5. Number of occupied breaker slots: (Count breakers that are currently installed)
  6. Number of empty slots: (Spaces with no breaker)
  7. Panel approximate age: (May be printed; otherwise compare to when your home was built or major work was done)
  8. Any labels, stickers, or notes on the panel: What information do they provide?

Questions: 1. Based on the main breaker amperage, classify your service as 60A, 100A, 150A, or 200A. Based on Chapter 13's discussion, is this service size likely adequate for your home's needs? 2. How many empty spaces are available for new circuits? If you wanted to add two new 120V circuits, would there be room? 3. Does your panel appear to be a type mentioned in the chapter as having documented safety concerns (Federal Pacific Stab-Lok or Zinsco/Sylvania)? If so, what is the recommended action?

Exercise 2: Map Your Panel — Complete Circuit Directory

Objective: Create a complete, accurate circuit directory for your panel.

Time required: 1–3 hours depending on the number of circuits and whether you have a helper.

What you need: Non-contact voltage tester (highly recommended), plug-in outlet tester or nightlight, pen and paper or the template below, flashlight, a helper if possible.

Safety note: You are flipping breakers in this exercise. This will temporarily cut power to portions of your home. Alert household members before beginning. Do not flip off medical equipment or systems that must remain on.

Instructions:

Use this template for your panel directory. Adapt to your actual panel layout:

PANEL DIRECTORY
Address: _______________________
Panel brand/model: _____________
Service size: _____ amps
Date mapped: ___________________

BREAKER  AMPS  TYPE        AREA/DEVICES SERVED
01       __    _________   _______________________________
02       __    _________   _______________________________
03       __    _________   _______________________________
04       __    _________   _______________________________
[continue for all breakers]

KEY: SP=Single-pole, DP=Double-pole, AFCI=AFCI breaker, GFCI=GFCI breaker
SPARE breakers: _______________

For each breaker: 1. Turn it off (if it's safe to do so) 2. Walk the home and note what is no longer powered 3. Test affected outlets with your nightlight or outlet tester 4. Record what the breaker controls 5. Turn it back on before proceeding to the next

After completing the map: - Laminate or place in a clear sleeve and affix inside the panel door - Photograph the completed map for digital backup

Questions: 1. Did you find any outlets or lights that you couldn't assign to a specific breaker? What might explain this? 2. Are any of your breakers double-tapped (two wires connected under one terminal)? Note: you'll see this through the panel door as two wires going into a single breaker. 3. Did you find any circuits serving more than one "zone" of the house in a way that seems inconsistent (e.g., one breaker controlling both a bedroom and a kitchen outlet)?

Exercise 3: Identify Breaker Types

Objective: Distinguish between standard, AFCI, GFCI, and double-pole breakers in your panel.

Instructions:

With the panel door open, examine each breaker and classify it:

  • Standard single-pole: Simple toggle, no buttons, no test lights
  • AFCI: Has a "TEST" button; may have an indicator light; typically labeled "AFCI" or "ARC FAULT"
  • GFCI: Has a "TEST" and "RESET" button; labeled "GFCI" or "GROUND FAULT"
  • Combination AFCI/GFCI: Has buttons for both functions
  • Standard double-pole: Two-slot breaker, connected with a handle-tie, no buttons — for 240V circuits
  • GFCI double-pole or AFCI double-pole: Two-slot with buttons

Create a tally: - Number of standard single-pole breakers: _ - Number of AFCI (or combination) breakers: - Number of GFCI breakers: _ - Number of standard double-pole:

Questions: 1. Based on NEC requirements described in Chapter 13, should your bedroom, living room, and family room circuits have AFCI protection? Do they currently have it? 2. If you added a new bedroom circuit tomorrow, would code require AFCI protection? What would that cost in terms of breaker type? 3. What percentage of your circuits currently have AFCI protection?

Exercise 4: Perform a Simplified Load Calculation

Objective: Estimate your panel's current calculated load and available headroom.

What you need: The appliance list from Chapter 12 Exercise 1, a calculator.

Instructions:

Follow the simplified load calculation from Section 13.6. Record your home's square footage and apply the steps:

Step 1: Lighting and general load Square footage: _ × 3 VA = ___ VA

Step 2: Small appliance circuits Number of kitchen small-appliance circuits × 1,500 VA = _ VA Laundry circuit: 1,500 VA Subtotal: ___ VA

Step 3: Apply demand factors First 3,000 VA × 100% = 3,000 VA Remainder at 35%: _ × 0.35 = VA Adjusted lighting/small-appliance load: __ VA

Step 4: Fixed appliances (list each from your home)

Appliance Voltage Amperage VA
Total

Step 5: HVAC Largest HVAC unit nameplate amps × voltage = _____ VA

Step 6: Total calculated load Add all above = _____ VA

Step 7: Convert to amps Total VA ÷ 240 = _____ amps

Step 8: Evaluate headroom Service size: _ amps Calculated load: amps Headroom: __ amps Headroom as % of service: _____%

Questions: 1. Is your panel headroom above 20% of service capacity? Below 20%? What are the implications? 2. If you added a Level 2 EV charger (48A dedicated circuit), how would that change your calculated load and headroom? 3. At what point (what additional load) would your current service become inadequate?

Exercise 5: Research Your Panel's Brand and Model

Objective: Determine whether your panel has any documented safety concerns or manufacturer advisories.

Instructions:

Using the brand and model information from Exercise 1:

  1. Search for "[panel brand] + [model] + recall or safety concern" online.

  2. Check the CPSC (Consumer Product Safety Commission) website at cpsc.gov for any recalls or safety notices related to your panel brand/model.

  3. Check whether your panel is a Federal Pacific Stab-Lok (look for red-striped breakers) or Zinsco/Sylvania brand (look for colored breaker handles — yellow, orange, blue). If it is either of these, read the CPSC documentation and the resources in this chapter's further-reading section.

  4. Check when your jurisdiction last adopted a new edition of the NEC (National Electrical Code). Look this up on your state or local building department website. Note the year.

Questions: 1. Did your research turn up any specific concerns with your panel brand or model? 2. If your panel was installed under an older NEC edition, what AFCI and GFCI requirements might apply if you were adding new circuits today that didn't apply when the panel was originally installed? 3. If you discovered that your panel is a documented problem brand, what is the practical path to replacement? Who do you call first?

Exercise 6: Understanding What Trips Your Breakers

Objective: Diagnose the cause of any frequently tripping breakers in your home.

Instructions:

Identify any circuit breaker in your home that trips more than once per year. For each:

  1. Record which circuit trips (from your panel map), the breaker amperage, and approximately when it trips.

  2. Estimate the load on the circuit when it trips: List all devices that were running on that circuit at the time of the trip. Find the wattage of each device from its nameplate or owner's manual.

  3. Calculate the total current draw at the moment of the trip: Sum all wattages ÷ 120V = total amps.

  4. Compare to the breaker rating. Is the total current above the breaker's rating? Above 80% of the rating for continuous loads?

  5. Consider other causes: Does the breaker trip on reset without any load, suggesting a short circuit or ground fault? Does it only trip when a specific device is running, suggesting a problem with that device?

For each tripping circuit, propose a solution: - Load redistribution (move some devices to a different circuit)? - Add a new circuit? - Repair or replace a faulty appliance? - Replace an aging breaker?

Questions: 1. Were any of your tripping circuits caused by loads that exceeded the 80% continuous load rule? 2. If a breaker trips on reset with no devices connected, what does that indicate? What is the appropriate next step? 3. What is the danger of repeatedly resetting a breaker that keeps tripping?

Exercise 7: The Cost of a Panel Upgrade — Get Real Numbers

Objective: Understand what a panel upgrade would actually cost in your market.

Instructions:

Whether or not you currently need a panel upgrade, this exercise builds the knowledge to evaluate the need intelligently.

  1. Identify your current service size (from Exercise 1) and your calculated load headroom (from Exercise 4).

  2. Determine what upgrade (if any) would be appropriate: 100A to 200A? 200A to 400A? New panel of same size because of age or brand concerns?

  3. Call or email three licensed electricians in your area. Ask for a ballpark estimate for: - A service upgrade to [target amperage] - Including permit and utility coordination - At your address

  4. Record the three quotes and any significant differences in scope, inclusions, or timeline. Note whether each contractor: - Asked whether a permit was needed (correct — it is) - Mentioned utility coordination - Offered to include AFCI/GFCI upgrades as required by current code

Questions: 1. How much do your three quotes vary? What factors seem to drive the price differences? 2. Did any contractor offer to do the work without a permit? What is the appropriate response? 3. How does your local market's pricing compare to the typical ranges described in Chapter 13?

Exercise 8: Sub-Panel Evaluation

Objective: Identify whether your home has any sub-panels, and evaluate their condition.

Instructions:

Search your home for any secondary electrical panels — in the garage, basement, attic, or an outbuilding. Sub-panels may look identical to the main panel or may be smaller.

If you find a sub-panel: 1. Identify the manufacturer and amperage rating. 2. Open the door and observe (cover on): Are the breaker slots mostly full or mostly empty? Is there a separate neutral bar and a separate ground bar (correct), or do they appear to share one bar (potentially incorrect — see section 13.1)? 3. Is the sub-panel connected to the main panel by a "feeder" cable? Can you trace where this cable goes? 4. Does the sub-panel have a main breaker? (Not always required if the feeder is protected by a breaker at the main panel.)

If you don't have a sub-panel but might benefit from one (e.g., a detached garage, a shop, an accessory dwelling unit): 1. Estimate the electrical needs of that space (lighting, outlets, any 240V equipment). 2. What amperage sub-panel would you need? (60A? 100A?) 3. How far is it from the main panel? (Distance affects feeder wire cost.)

Questions: 1. What is the main advantage of a sub-panel over running individual circuits from the main panel to a detached structure? 2. If a sub-panel's neutral and ground bars are bonded together, why is this a problem (even though it's correct in a main panel)? 3. Dave Kowalski wants to add a sub-panel for his shop. Using Chapter 13's pricing guidance, estimate the cost of a 100-amp sub-panel installation 50 feet from the main panel in a detached building.