--- title: Rewiring a Hundred-Year-Old Home: What to Expect From Start to Finish description: Tackle [av_keyword_plain] with confidence. Learn what knob and tube wiring hazards mean for your Scottsdale home and how [main_name] handles every step. url: https://fhrelectric.com/rewiring-a-hundred-year-old-home-what-to-expect-from-start-to-finish date_modified: 2026-08-16 author: language: en_US --- If you’ve just pulled back some drywall during a remodel — or your home inspector handed you a report that made your stomach drop — you already know the feeling. That tangle of cloth-wrapped wires and ceramic knobs is not a charming relic. It’s a liability. is one of the most complex projects a licensed electrician takes on, and in — where historic homes near Old Town Scottsdale sit alongside newer builds on the same street — we see this more often than you’d expect. Here’s exactly what the process looks like, start to finish, so you can walk in informed and confident. ## Why Knob and Tube Wiring Hazards Are a Modern-Day Problem Knob and tube was engineered for homes running a few light fixtures and maybe an icebox. It has no ground conductor, the insulation is brittle and cracks with age, and it was never designed to share a junction box with blown-in insulation — which traps heat around conductors that need to breathe. That combination raises fire risk in a measurable way. Arizona homeowners insurance carriers have started flagging it, and some won’t renew a policy until it’s gone. Beyond the fire question, consider what a century-old home in the Phoenix metro is being asked to power today: a 240-volt EV charger, a 5-ton HVAC system, a whole-kitchen remodel, and smart home devices on every wall. The original wiring wasn’t built for any of that. If your [breaker keeps tripping](https://fhrelectric.com/breaker-keeps-tripping-heres-what-its-actually-telling-you/) and resetting doesn’t hold, the wiring is telling you something real. > “Knob and tube has no ground conductor and insulation that cracks with age — it was never designed for the loads a modern Arizona home demands.” ## The Real Scope of a Whole-House Rewiring Project ![A licensed electrician removing knob and tube wiring during a century old home rewiring project inside a vintage Arizona residence](https://fhrelectric.com/wp-content/uploads/2026/08/avathan-6a78437f001ed.jpg "Rewiring a Hundred-Year-Old Home: What to Expect From Start to Finish") People ask us all the time: *how disruptive is whole house rewiring, really?* Honestly — it depends on the home’s construction, square footage, and what’s already been updated. Here’s the honest breakdown of every phase: - **Assessment and load calculation.** Before a single wire is pulled, we do a full [electrical load assessment](https://fhrelectric.com/what-a-home-electrical-load-assessment-actually-involves-and-why-you-need-one-before/) to map what your home actually draws — and what it will draw after the upgrade. This shapes panel sizing, circuit counts, and permit scope. - **Permit and inspection scheduling.** In Maricopa County, a rewire requires a permit. We handle that. No permit means no inspection, and no inspection means no proof the work was done right — that matters enormously at resale. - **Wall access and fishing wire.** In plaster-and-lathe construction, access holes are cut strategically so they close cleanly. On a high square footage home rewiring, we plan access points room by room to keep patch work manageable. Most homeowners stay in the house throughout — we work in sections. - **Panel upgrade.** Almost every old home rewire means a new panel. A 60-amp service from 1925 won’t support a modern home. We size up to 200-amp minimum; many [Scottsdale homes now warrant 400-amp service](https://fhrelectric.com/is-200-amp-service-still-enough-for-a-modern-arizona-home/) depending on their load profile. - **New circuits, devices, and grounding.** Every outlet, switch, and fixture gets replaced with grounded, code-compliant hardware. AFCI and GFCI protection is added where NEC requires it. - **Thermal imaging sign-off.** Once the work is complete and the walls are closed, we run a thermal imaging scan of the panel and key circuits. It’s how we prove the job is clean — and it’s something a one-truck operator is unlikely to offer. ## What It Typically Costs — and Why Ranges Vary ![A licensed electrician removing knob and tube wiring during a century old home rewiring project inside a vintage Arizona residence](https://fhrelectric.com/wp-content/uploads/2026/08/avathan-6a78438d81d4b.jpg "Rewiring a Hundred-Year-Old Home: What to Expect From Start to Finish") A whole-house rewire on a historic home in typically runs anywhere from **$8,000 to $20,000+**, depending on square footage, the condition of existing wiring, whether a panel upgrade is included, and how much drywall access is required. Larger homes — say, 3,000 square feet and up in North Scottsdale or Fountain Hills — sit toward the higher end of that range. If you’re also adding an EV charger or upgrading to 400-amp service, those are separate line items. What you won’t get from us is a number that balloons mid-job without a conversation first. If your home also has a [Zinsco, Pushmatic, or Challenger panel](https://fhrelectric.com/zinsco-pushmatic-and-challenger-panels-why-these-brands-are-red-flags/) hiding behind the old knob and tube — which happens more than you’d think in homes that had partial updates over the decades — that replacement is non-negotiable, not optional. The good news: bundling it into the rewire scope is the most cost-efficient way to handle it. ## The Old Home Electrical Upgrade: What Changes After Picture flipping every switch in your home and feeling nothing but confidence. No hum from the panel. No warm outlet covers. No tripped breaker at 8 p.m. when the AC and the dryer run at the same time. That’s the real outcome of a properly executed old home electrical upgrade — not just compliance, but a home that supports your actual life. For homeowners in who are also planning EV charging, the rewire is the right time to rough in that circuit. Check out [what a Wallbox EV charger installation actually involves](https://fhrelectric.com/wallbox-ev-charger-installation-what-the-job-looks-like-from-panel-to-plug/) to see how it layers into a larger project. Doing it after the walls close again means cutting them back open — nobody wants that. If you’ve recently purchased a home near Camelback Road, the McCormick Ranch area, or anywhere in Chandler or Gilbert where older neighborhoods sit next to newer developments, get an inspection before you assume a previous owner already handled it. What home inspectors flag most often in [older properties](https://fhrelectric.com/what-home-inspectors-flag-most-often-and-what-to-do-about-it/) is exactly this — partial updates that left hazardous original wiring in place. We’ve been licensed and working in and across Maricopa County for over 20 years. That track record means permits get pulled, inspections get passed, and thermal imaging confirms the work is clean — every time. If you’re ready to stop wondering what’s behind your walls, call at . We’ll give you a straight answer and a straight price. [Call for a Free Estimate —](tel:(602) 492-9999)