Knob-and-Tube Wiring in an Older Massachusetts Home: What It Costs to Deal With During a Remodel

Last reviewed 2026-10-16

If your remodel turns up knob-and-tube wiring, plan on replacing the circuits in the rooms you are opening, and budget roughly $3,000–$9,000 for that rewire inside the remodel, plus $2,500–$7,000 if the house also needs a 200-amp service upgrade. Doing it while the walls are already open is the cheapest moment you will ever get. The electrician pulls the electrical permit, the work gets inspected, and then the walls close up.

What knob-and-tube is, and why Central MA has so much of it

Knob-and-tube is the wiring method used in most American houses built from roughly the 1890s into the 1930s and early 1940s. Single conductors run separately through ceramic tubes in the framing and along ceramic knobs, with air around each wire to shed heat. There is no ground conductor.

Central Massachusetts is full of houses from that era. Mill-town triple-deckers in Clinton, Worcester and Fitchburg, and antique colonials and farmhouses in Harvard and Lancaster, often still have original circuits live. A house can look updated at the panel and still have knob-and-tube feeding the upstairs bedrooms.

Why it becomes a problem the moment you remodel

Knob-and-tube that has been left alone for 90 years is not automatically on fire. The trouble is what a remodel does to it:

• No ground. Modern kitchens and baths need grounded and GFCI-protected outlets. You cannot properly tie new kitchen or bath circuits into ungrounded wiring.
• Insulation buries it. The system depends on open air to cool the wires. The National Electrical Code (Section 394.12) says concealed knob-and-tube shall not be used in hollow spaces that are insulated with loose, blown-in, rolled-in or foamed-in insulation that envelops the conductors. Massachusetts adopts the NEC with state amendments as the Massachusetts Electrical Code, 527 CMR 12.00. Mass Save also treats live knob-and-tube as a barrier that has to be dealt with before insulation work goes in.
• Brittle insulation and buried splices. A century of heat, rodents and past add-ons leaves cloth-and-rubber insulation cracked and splices hidden.
• Insurance carriers. Many home insurance carriers will not write a new policy on a house with active knob-and-tube, or charge more until it is replaced. Not universal, but common.

Why open walls are the cheapest moment to replace it

Most of the cost of a rewire is access: getting new cable through finished plaster without tearing the house apart. Once a kitchen or bathroom is open to the studs, new grounded circuits go in without the fishing and cutting.

So we plan for it up front. On a kitchen or whole-floor renovation, we would rather know about knob-and-tube at the walkthrough than find it after cabinets are ordered. Our guide to surprises in older Central MA kitchen remodels covers the other things that tend to show up alongside it.

What it costs during a remodel

Our typical ranges for work coordinated inside a remodel. Your number depends on how many circuits are still live and how much of the house is open.

Older houses rarely hide just one thing. Knob-and-tube and galvanized water lines often travel together, which is why our bathroom remodel cost guide for Massachusetts builds in room for hidden conditions.

The 60-amp or 100-amp service question. Many pre-war houses still run on a 60-amp or 100-amp service. A new kitchen plus a heat pump can push past what that service carries. The electrician runs a load calculation, and if the answer is 200 amps, doing it in the same project means the utility coordination, meter work and new panel happen once instead of twice.

Permits, inspection, and who does what

The electrician pulls the electrical permit with your town and calls the wiring inspector for rough and final inspections. Maverick City Builders is the general contractor: we schedule the electrician, sequence demo and framing around their rough-in, and handle the building permit side. We do not do the electrical work ourselves. See our overview of building permits in Central Massachusetts for how the different permits fit together.

How it is sequenced inside a kitchen or bath remodel, and the timeline

A typical sequence looks like this:

1. Walkthrough and assessment. The electrician confirms which circuits are still knob-and-tube and whether the service needs upgrading.
2. Lead-safe demo. Plaster in pre-1978 homes is treated as containing lead paint. We hold the Massachusetts lead-safe renovation credential and follow the state programme’s containment and cleanup practices when opening walls.
3. Electrical rough-in. New grounded circuits go in; old runs in the work area are disconnected and abandoned or removed. Inside an open room this goes quickly; the size of the scope sets the days.
4. Rough inspection. The wiring inspector signs off before anything is closed up.
5. Fishing beyond the remodel. Circuits in finished rooms are fished through small openings. Expect a few days of plaster patching afterward.
6. Insulation, drywall, finishes. Only after inspection.

The added time comes mostly from the inspector’s schedule in your town and plaster patching outside the remodel area, so we build both into the schedule at the start. For matching patched plaster and old trim, see our notes on painting older homes in Massachusetts.

Where we work

We are based in Lancaster and work across Central Massachusetts and MetroWest, including Clinton, Worcester, Fitchburg, Harvard, Sterling, Bolton, Hudson, Leominster and Concord. Pre-war housing is a big part of what we see in these towns.

If you are planning a remodel in an older house and suspect knob-and-tube behind the plaster, request an estimate. We will walk the house, bring the electrician into the plan early, and give you a scope that accounts for what is in the walls before demo starts.