Case Study 13-2: The Chen-Williams Renovation — Full Electrical Upgrade in an Open House

When Priya and Marcus Chen-Williams bought their 1963 suburban ranch, they knew they were buying a project. The bones were solid — good lot, quiet neighborhood, original hardwood floors under the carpet, a layout that had weathered 60 years of use with its logic intact. But the house had been maintained minimally, never renovated, and showed every one of its years.

Their plan was a gut renovation: new kitchen, new bathrooms, updated electrical, updated plumbing, new HVAC. All-in. Not cosmetic — structural.

The electrical component ended up being larger than they'd anticipated going in, and more interesting than they'd expected.

The Pre-Renovation Inspection

Before demolition began, their general contractor scheduled a licensed electrician for a full electrical inspection. Marcus, who managed projects professionally and understood the value of thorough pre-work, attended the inspection and took notes.

The electrician spent two hours in the house. His findings:

The existing panel: A 100-amp Federal Pacific Stab-Lok panel with the characteristic red-stripe breakers. As described in Chapter 13, Federal Pacific panels have documented failures in the breakers' trip mechanism — breakers may fail to trip on overcurrent. The electrician's recommendation was direct: "Replace this panel regardless of anything else we decide about the service size. I won't do new work feeding off a Stab-Lok panel."

The wiring: Three generations of wiring were in the house: - Original 1963 wiring: knob-and-tube in two of the three bedroom walls, the hallway, and portions of the living room - 1967–1968 partial rewire (probably coinciding with central AC installation): aluminum branch circuit wiring in the kitchen, dining room, and master bedroom — this was during the aluminum branch circuit period - 1980s additions: standard copper NM cable in the family room addition and the third bedroom added at some point

The buried junction boxes: In the attic, the electrician found two splices that were not in boxes — just wire nuts on the knob-and-tube wiring, loose in the blown-in attic insulation. K&T wiring buried in insulation is a known fire hazard; wire splices outside of boxes violate NEC 314.29.

The assessment summary: "You're looking at rewiring everything from scratch. The K&T, the aluminum circuits, and the buried splices all need to go. Given that you're opening walls anyway, this is the right time. The cost of rewiring with walls open is substantially less than rewiring with walls closed."

Scoping the Electrical Work

Priya and Marcus had already been planning to convert from gas appliances to all-electric as part of the renovation — it aligned with their goals to reduce their carbon footprint and take advantage of federal tax credits available for heat pumps and electric appliances under the Inflation Reduction Act. The electrical scope now had to support:

• Full house rewire (removing all K&T and aluminum branch circuits)
• New 200-amp service
• All-electric kitchen (induction range, electric oven)
• Heat pump replacing gas furnace
• Heat pump water heater replacing gas water heater
• Level 2 EV charger in the garage
• Updated bathroom circuits with GFCI
• Home office circuit (Marcus works from home)
• Whole-house AFCI protection on bedroom and living area circuits

They ran a load calculation (see Chapter 13, section 13.6) and arrived at approximately 160 amps of calculated load — comfortably within a 200-amp service but leaving only about 25% headroom. Their electrician pointed out that if they ever wanted to add a second EV charger or any significant additional load, they'd be back near capacity.

The decision point: 200-amp or 400-amp service?

The electrician laid out the options honestly: - 200-amp service: Sufficient for current plans. Upgrade cost differential vs. 400-amp: approximately $2,500 less upfront. If they later need more capacity, upgrading from 200A to 400A runs $4,000–$6,000. - 400-amp service (two 200-amp services): More expensive now, essentially unlimited residential capacity going forward. Would require utility to verify the transformer serving their block can handle the additional load (likely yes, but adds coordination time).

Priya and Marcus chose 200 amps. Their reasoning: they had no concrete plans for additional EV charging, the 25% headroom was adequate, and they could revisit if circumstances changed. "We're not going to spend $2,500 now to solve a problem we don't have," Marcus said. This is a reasonable position, and it's worth noting that the "right" answer depends entirely on specific plans and budget.

The Scope of Work and the Permit

The general contractor's electrical subcontractor pulled the permit. For a renovation of this scale — full house rewire, service upgrade, new panel — the permit fee was $380. The permit required:

1. A rough-in inspection before walls were closed (the inspector verified wire routing, box placement, and circuit assignments before drywall)
2. A final inspection after completion

The rough-in inspection proved valuable. The inspector noted that the electrician had not installed a bonding jumper on the metal gas lines (the house still had gas lines running to the fireplace, even though appliances were switching to electric). This is a bonding requirement under NEC 250.104. The fix took about 20 minutes. Without the inspection, this would have remained an uncorrected deficiency.

What the Rewire Found in the Walls

As the demolition proceeded and walls opened up, the electrical findings grew more interesting. In the kitchen, the aluminum branch circuit wiring from 1967 had been extended at some point using standard wire nuts — not the CO/ALR rated connectors required for aluminum-to-copper connections. The extension had been in place for decades without incident, but the connection was improper.

In one bedroom wall, the original knob-and-tube wiring had been extended with NM cable using a wirenut splice inside the wall cavity — not in a box, not accessible. This was someone's solution to an outlet that had stopped working, probably 30 or 40 years ago. The splice had held, but it violated every relevant requirement.

These discoveries reinforced what the pre-renovation inspection had suggested: older homes hold surprises. The rewire proceeded systematically, circuit by circuit, with everything documented on the panel directory.

The Final Panel

The new panel was a 200-amp, 40-space Square D QO load center with a main breaker. The electrician's circuit assignments:

• All bedroom circuits: AFCI single-pole breakers
• Kitchen countertop circuits (2 dedicated 20-amp): GFCI at breaker
• Bathroom circuits: GFCI at breaker
• Induction range: 50-amp double-pole (10-gauge wire)
• Heat pump: 30-amp double-pole (10-gauge wire)
• Heat pump water heater: 30-amp double-pole (10-gauge wire)
• EV charger: 50-amp double-pole (6-gauge wire)
• Home office: 20-amp AFCI
• Garage outlets: 20-amp GFCI
• Outdoor outlets: 20-amp GFCI

The panel was labeled with a detailed directory. Twenty spaces remained empty.

The Outcome

Total electrical cost for the renovation: $14,200, including service upgrade, full rewire, and new panel. This was approximately 18% of their total renovation budget — and their general contractor had told them to expect 15–20% for electrical in a full gut renovation of a same-era house.

Marcus ran the numbers on the energy side. Switching from gas to all-electric with a heat pump meant their winter energy bills would change substantially — gas costs would disappear, electricity would increase, but the heat pump's efficiency (3:1 coefficient of performance — 3 units of heat for every unit of electricity) meant net energy cost per BTU would be lower than their old gas furnace.

Their calculated first-year electricity increase from the added loads: approximately $900. Their calculated gas cost elimination: approximately $1,100. Net savings in year one: roughly $200 — not dramatic, but in the right direction, and improving each year as gas prices fluctuated while the heat pump's cost structure remained stable.

The federal tax credits for the heat pump, heat pump water heater, and EV charger infrastructure reduced their effective renovation cost by $4,500 — more than covering the entire electrical panel upgrade.

"We've been in this house six months," Priya said, "and we haven't once thought about the electrical system. No trips, no strange behavior, no weird outlet. It just works the way it's supposed to. That's what you're paying for."

Discussion Questions

1. The electrician refused to do new work feeding off the Stab-Lok panel. Is this a reasonable professional standard? What are the electrician's liabilities if they connect new work to a panel with a documented safety deficiency?
2. Priya and Marcus chose 200-amp over 400-amp service. What specific circumstance would make them regret this decision in 5–10 years? What circumstance would confirm it was the right choice?
3. The permit's rough-in inspection caught a missing bonding jumper on the gas lines. This took 20 minutes to fix with walls open. Estimate how difficult and expensive this correction would have been if discovered after walls were closed.
4. The Chen-Williams renovation converted from gas to all-electric. Their net energy savings in year one was modest ($200). But they plan to stay in the house 20+ years. What factors might make the all-electric choice more financially compelling over time?