Whole-home rewiring is the work nobody wants to do until they have to. The trigger is usually one of three things. An older home with knob-and-tube or aluminum branch wiring fails an insurance inspection. A renovation opens walls and reveals scorched terminations or undersized conductors. Or a homeowner adds enough modern load (HVAC, EV, kitchen reno) that the existing wiring stops keeping up.
The three big wiring eras matter. Knob-and-tube ran from roughly 1880 to 1940 and used separate hot and neutral conductors with ceramic insulators. It can be safe when undisturbed but fails when buried in modern insulation, modified by a non-electrician, or asked to carry modern grounded loads. Aluminum branch wiring ran from 1965 to 1973 in residential 15A and 20A circuits and has well-documented failure modes around terminations, called out in CPSC alerts. Cloth-jacketed Romex from the 1950s-1970s often lacks an equipment grounding conductor.
None of those eras are inherently “unsafe.” All of them have known failure modes that need verification before we sign off on a home for sale, an addition, or any major load addition. The homeowner’s question becomes: what’s the access path, what’s the sequencing, and what’s the realistic timeline.
When does a home need rewiring vs targeted repair?
Rewiring is the right scope when the existing wiring system has multiple, systemic issues that can’t be addressed circuit-by-circuit. Common signs are knob-and-tube still in active use, aluminum branch wiring in living-area circuits without proper aluminum-rated devices or anti-oxidant treatment, two-prong outlets on most circuits indicating no equipment ground, breakers that trip at random under modern loads, or a panel that has been pushed past its original capacity by a series of additions.
Targeted repair is appropriate when the issues are localized. a single damaged circuit, a specific kitchen branch that needs upgrading, or a service mast repair after storm damage. We diagnose first, then quote rewire vs targeted scope, then work with the homeowner on the trade-offs.
Knob-and-tube, aluminum, and aged Romex
Each of these wiring types has a specific failure pattern we look for during inspection. Knob-and-tube fails at splices made in the wrong locations (inside walls without junction boxes), at points where modern insulation contacts the conductors, and at any modification where someone added a ground wire or a modern outlet without addressing the system’s design. We document the routing and identify whether targeted replacement (de-energize the K&T circuit, run new) or full rewire makes sense.
Aluminum branch wiring fails at terminations. The metal expands and contracts more than copper under load, which loosens screw terminations over time. The fix is either replacement with copper (the gold standard), retrofit with COPALUM crimps (an approved CPSC remediation), or AlumiConn connectors. We assess and recommend the right path per circuit.
Cloth-jacketed Romex from the 50s-70s often lacks an equipment grounding conductor. Three-prong outlets installed on these circuits without rewiring (or without GFCI protection per NEC 406.4(D)) violate code. We trace each circuit and identify which outlets can be brought into compliance with GFCI protection vs which need new wiring.
Access path: open walls vs minimal disruption
Skilled rewires use existing wall cavities, attic and crawl space access, and small fish-tape paths to minimize wall damage. The trade-off is time. A “minimal disruption” rewire on a finished home runs longer than a rewire on a home where walls are already open for renovation.
We document the access plan room by room. Each circuit has a path from the panel to the devices, and that path either uses existing routes (often the case for circuits running through the basement or attic), small drywall cuts at strategic points, or surface-mounted conduit in unfinished spaces. The plan goes in the written scope so the homeowner sees the trade-off between cost, time, and patch work.
For homes scheduled for renovation, the clean answer is “rewire during the open-wall phase.” We coordinate with the GC on rough-in timing and run new circuits while the walls are stripped to studs.
Sequencing: keeping the home livable
Most rewires are sequenced so the home stays usable during the project. We take circuits offline one section at a time, reroute the affected loads (extension cords for refrigerators, temporary lighting), and bring the new circuits online before disabling the next section.
Refrigeration is the constraint that drives most sequencing decisions. We plan around when the kitchen circuits go down. Same with HVAC and the home office circuits if anyone works from home. Health and medical equipment plans get documented in writing before we start.
Permit and inspection
Rewires require permits in nearly every jurisdiction. The permit covers the new branch circuits, any panel work, and the grounding system. Inspections typically happen in two phases. The rough inspection happens after wiring is run but before walls are closed up. The final inspection happens after devices are installed and the system is energized.
Inspectors check conductor sizing per NEC 310, junction box accessibility per NEC 314.29, GFCI and AFCI protection per NEC 210.8 and 210.12, and the grounding electrode system per NEC 250. We pull the permit, schedule any inspections, and meet any inspector for both rough and final.
Realistic timelines
A typical single-family rewire runs 1-2 weeks of on-site work depending on home size, finish complexity, and how many circuits need to be added. Open-wall rewires during renovation are faster (no patching). Minimal-disruption rewires on finished homes are slower (more careful access). We confirm the timeline in the written scope and update the homeowner if anything in the field changes the plan.
Older home considerations
Older homes often surface secondary issues during a rewire. The grounding electrode might be a single rod from the 1950s where current code requires two rods (NEC 250.53). The service mast might be undersized for the planned panel upgrade. The neutral might be undersized in the service entrance conductors. We document everything we find during the rewire and quote any additional scope before the work continues.
We also document undersize neutrals on shared-neutral circuits, which can overheat under modern loads even when the breaker doesn’t trip. This is a real failure mode in 1960s-1970s homes that we look for specifically.
What we tell every customer before rewire day
Pack like it’s a partial move. Cover furniture, remove anything fragile from walls, and clear the rooms where we’ll be working. Rewires are dusty.
Plan for refrigerator and food storage. We minimize downtime on the kitchen circuit but it does go offline for sections of the project.
Decide on switch and outlet finishes before we start. We can install whatever the homeowner picks, but trying to swap finishes mid-project adds friction.
Expect surprises. Older homes always reveal something during a rewire. We document and quote, the homeowner approves, and we continue. The clean projects are the ones where this conversation happens before we open the wall, not after.
Wiring methods and cable types
Modern residential wiring uses three primary methods, each with its own use cases and code requirements:
NM-B (Romex)
Non-metallic sheathed cable, the most common residential wiring method. Two or three insulated conductors plus a bare ground, all in a flexible plastic jacket. NM-B runs through framed walls, attics, and basements where it is protected from physical damage. NEC 334 governs NM-B installation: stapled to framing within 12 inches of boxes, supported every 4.5 feet, protected at openings, and not exposed where physical damage is a concern.
Common sizes: 14 AWG for 15-amp circuits (lighting, general outlets), 12 AWG for 20-amp circuits (kitchen small-appliance, bathroom, laundry, dedicated outlets), 10 AWG for 30-amp dedicated circuits (water heater, dryer, smaller appliances).
Metal-clad cable (MC)
Conductors inside a flexible metal armor. Used in commercial, in some residential applications where physical protection matters, and where the AHJ requires metal raceway. MC has its own installation rules per NEC 330. More expensive than NM-B but more durable.
Conduit (THHN/THWN-2 conductors in EMT, PVC, or FMC)
Individual insulated conductors pulled through a metal or plastic conduit. Required for service entrance work, exterior runs, runs in concrete or masonry, and locations where physical damage is likely. NEC 358 (EMT), NEC 352 (PVC), and NEC 348 (FMC) govern conduit installation. Conduit lets the same physical run carry different combinations of conductors over time, useful for future-proofing.
Rewiring scope categories
Rewiring jobs fall into a handful of categories. Knowing which category fits before the quote keeps the scope honest:
Single-circuit rewiring
One specific circuit is failing or unsafe, a kitchen counter circuit, a bathroom circuit, an exterior outlet, or a circuit that has been modified by previous owners and needs to be returned to code. The work is targeted: open the path of the existing circuit, pull new cable, terminate at the panel and at the device locations, document and inspect. Often completes in a single day for a typical-length run.
Room-level rewiring
An entire room, kitchen, bathroom, bedroom, or office, is being rewired during a remodel. Scope includes all the room’s circuits: lighting, outlets, dedicated circuits for appliances. Done while walls are open during the remodel, the work is significantly cheaper than the same scope after walls close.
Targeted whole-area rewiring
The attic and ceiling cavities (where insulation has been packed around old knob-and-tube), or the entire upstairs (where a renovation is opening floors), or all kitchen/bath/laundry circuits (the highest-load areas). Targeted to the highest-risk or highest-load areas without rewiring every circuit in the home.
Whole-home rewiring
The worst-case scope. Every branch circuit in the home is replaced. Reserved for homes where wiring throughout has documented issues, knob-and-tube with insulation packed everywhere, aluminum branch wiring throughout, fabric-jacket wiring that is widely deteriorated, or amateur modifications that compromise multiple circuits. Multi-day project, requires careful staging, sometimes allows the homeowner to live in the home during work and sometimes not.
Junction box discipline and why it matters
One of the most common amateur-installation issues we find during rewiring scopes is hidden splices, wire nuts in walls or attics without a junction box. NEC 314 requires every splice to be in a junction box, with the box accessible (or specifically allowed by the AHJ in some assemblies). The reason is mechanical: a splice in an unsupported wire nut, in a wall cavity with no box, can pull apart over time, can heat from compromised contact, and is unreachable for inspection or repair.
NEC 314.16 specifies box-fill calculations, how many conductors a given box size can hold, accounting for the volume taken by each conductor, each device, and each ground. Box-fill violations are a common finding during inspection of older work. The fix is either a larger box or fewer conductors at that location.
Every Keil Electric rewiring scope includes accessible junction boxes at every splice, box-fill calculations per NEC 314.16, and labeled circuits at the panel per NEC 408. Hidden splices are not part of any quote we sign.
Rewiring older homes by era
The wiring you find depends heavily on when the home was built:
- Pre-1940. Knob-and-tube wiring is the default. Look for porcelain knobs supporting individual conductors and porcelain tubes at framing penetrations. Insulation buried around the wiring is the modern hazard.
- 1940-1965. Early flexible armored cable (BX) and cloth-jacketed NM cable predominate. The jacket can deteriorate; the conductors inside are usually copper.
- 1965-1973. Aluminum branch wiring window. CPSC alerts apply. Remediation is COPALUM/AlumiConn pigtailing, CO/ALR receptacle replacement, or full rewire in copper.
- 1973-1990. NM-B copper wiring becomes standard. Watch for early NM-B without an equipment grounding conductor, three-prong receptacles on those circuits are a code violation unless protected by GFCI.
- 1990-present. Modern NM-B with separate ground, AFCI required on living-area circuits in current code editions, GFCI required in expanded locations. The wiring tends to be code-compliant; the issues are usually amateur modifications layered on.
Rough-in and final inspection
Permitted rewiring scopes have two inspections: rough-in and final.
Rough-in is when the wiring is installed but the walls are not yet closed. When an inspection is required, the inspector verifies that boxes are correctly sized and supported per NEC 314, that conductors are properly secured per NEC 334.30 (for NM-B) or the relevant code section, that splices are in boxes, that the cable is protected at openings, and that grounding is continuous. Rough-in must pass before drywall closes.
Final is after devices are installed, the panel is energized, and the home is ready for occupancy. When an inspection is required, the inspector verifies that GFCI per NEC 210.8 and AFCI per NEC 210.12 are installed and functional, that breakers are correctly sized and labeled per NEC 408, that the grounding electrode system is intact, and that the install matches the plans submitted with the permit.
Final inspection is the last gate before the work is officially complete. We pull the permit, schedule both inspections, and the install is backed by our written warranty.
House rewire and whole home rewire scope
A house rewire (also called whole home rewire) replaces the branch wiring throughout the home, typically because the original wire is at end of life, has documented failure modes (knob and tube, aluminum branch wiring from the 1965-1973 era), or is undersized for current load. We do whole home rewire jobs as a planned multi-day to multi-week project, usually staged room by room so part of the home stays powered each day.
Wiring upgrade scope ranges from a single circuit (replacing a damaged or undersized run) to the full house rewire on older homes. For aluminum branch wiring specifically, we either replace runs end-to-end or pigtail with copper using approved CO/ALR connectors, depending on the actual condition of the aluminum and the insurance or sale requirements driving the job. Knob and tube replacement is similar: targeted vs full depending on what is actually live and what is abandoned in the wall.