# Knob and Tube Replacement in Cambridge, from Baldwin to North Cambridge

> Knob and tube replacement in Cambridge: where the city's permits cluster, clearing old wiring for insulation, Cambridge ISD fees and Historical Commission.

URL: https://deckerbostonknobandtube.com/service-areas/cambridge/

Cambridge Inspectional Services Department

issues the electrical permit (City of Cambridge)

Eversource

electric utility

94

electrical permits naming knob and tube, Nov 2021 to Oct 2026

02138, 02139, 02140

ZIP codes

## What usually starts a rewire in Cambridge

### The insulation contractor stopped work

An energy assessment found knob and tube in the attic or walls, and nothing can be blown in until a licensed electrician certifies the work areas.

### One unit is being renovated

An owner redoing a single condo or apartment finds original circuits in its walls, and the job has to stay inside that unit's boundaries.

### The front hall lights are on old wiring

Thirty-one of the 155 Cambridge permits naming knob and tube mention hallways, common areas or stairs, where the circuits can predate every unit's updates.

### The sub-panel is 60 amps

A unit fed from a small sub-panel may need more capacity once its circuits are replaced and arc-fault breakers added.

## Services in Cambridge

### Insulation Barrier Work →

The licensed electrician's work and certification that clear a Mass Save knob and tube barrier, so recommended insulation can go in.

### Partial Replacement →

The circuits still on knob and tube replaced from the panel to the last device, with a written record of anything left for a later phase.

### Triple-Deckers and Multi-Family →

Knob and tube replaced across occupied apartments, shared stairs and basements in three-deckers, two-families, condos, brownstones and rowhouses.

### Knob and Tube Inspection →

A licensed electrician traces every circuit, finds which old runs still carry power and puts the findings and a recommended scope in writing.

### Fuse Box and Panel Upgrades →

Fuse boxes and full panels replaced, and 60 or 100 amp services enlarged where the load calculation calls for it, planned together with the rewire.

### Whole-House Rewiring →

Every branch circuit replaced with new grounded cable, for houses where knob and tube, cloth cable and old splices are mixed through the walls.

“Remove knob and tube so customer can insulate.” That is the whole description on one City of Cambridge electrical permit, and it sums up how much of the city’s knob and tube work begins: with an insulation project that can’t go ahead until the old wiring is out of service. [Decker Boston Knob and Tube](https://deckerbostonknobandtube.com/) arranges knob and tube replacement across Cambridge, from Agassiz-Baldwin and Neighborhood Nine to Mid-Cambridge, North Cambridge and Cambridgeport, carried out by licensed and insured electrical contractors.

Cambridge has its own permit office, its own fee schedule and its own historic review, separate from Boston’s. The job usually starts with a [knob and tube inspection](https://deckerbostonknobandtube.com/knob-and-tube-inspection/) that finds which circuits are live and which unit or common area each one serves.

## Where Cambridge’s knob and tube permits cluster

Cambridge publishes its electrical permits as open data, which shows clearly where the old wiring is being replaced: the residential neighborhoods west and north of Harvard Square.

Between November 2021 and October 2026, 94 of 13,591 electrical permits named knob and tube. The neighborhood breakdown shows the concentration.

| Neighborhood | Permits naming knob and tube | All electrical permits | Per 1,000 |
| --- | --- | --- | --- |
| Baldwin | 29 | 913 | 31.8 |
| Strawberry Hill | 4 | 216 | 18.5 |
| Mid-Cambridge | 13 | 1,169 | 11.1 |
| Neighborhood Nine | 12 | 1,135 | 10.6 |
| North Cambridge | 15 | 1,559 | 9.6 |
| West Cambridge | 14 | 1,747 | 8.0 |
| Cambridgeport | 5 | 1,236 | 4.0 |
| Riverside | 2 | 866 | 2.3 |

East Cambridge and Area 4 recorded none in that window. Descriptions are free text, so a permit that says only “rewire” isn’t counted, and the figures show where old wiring is being written up, not which houses still have it.

## Clearing the way for insulation

When knob and tube is found during an energy assessment, insulation stops until a licensed electrician certifies the work areas. In Cambridge, that rule shows up directly in the permit text.

### The Mass Save rule

Mass Save’s assessment standards say that if any evidence of knob and tube is found, no insulation may be installed until a licensed electrician addresses the wiring. The customer needs certification that the home is free of active knob and tube in every area where work is recommended. Air sealing and duct work can sometimes go ahead if the wiring isn’t disturbed.

### What the electrician delivers

The certification is area by area, so the scope can match the insulation plan. One Cambridge permit reads “Remove knob & tube wiring in Basement and Attic in preperation of insulation.” Where only those areas are being insulated, the job may be a targeted [insulation barrier](https://deckerbostonknobandtube.com/knob-and-tube-insulation-barrier/) clearance rather than a full rewire, with the boundary written down. The [guide to telling whether knob and tube is live](https://deckerbostonknobandtube.com/guide/how-to-tell-if-knob-and-tube-is-live/) explains why inactive runs are treated differently.

## One unit, the common stairs, or the whole house

Only 9.9% of Cambridge’s housing units are detached houses, and 54.5% are in buildings of five or more. Most knob and tube permits here are in multi-family buildings, 56 against 35 in one- or two-family dwellings over the last five years.

### Unit by unit

A common scope is a [partial replacement](https://deckerbostonknobandtube.com/partial-knob-and-tube-replacement/) covering one apartment or condo. A 2019 permit reads “unit #3 rewire knob and tube … install 60 amp sub panel,” and 15 of the city’s 155 permits naming knob and tube mention a sub-panel. Where each unit gets its own panel, the work becomes a staged [triple-decker or multi-unit rewire](https://deckerbostonknobandtube.com/triple-decker-rewiring/).

### Hallways and stairs

Thirty-one of those 155 descriptions name hallways, common areas or stairs. Massachusetts lets common-area lighting on the same floor as a unit, in a two-family or an existing three-family building, be fed from that unit’s equipment, which can keep the stair lights off a separate house panel.

### Panel and service

Forty-one of the 155 mention a service or panel, and in a one- or two-family house a panel change may come with a [whole house rewire](https://deckerbostonknobandtube.com/whole-house-rewiring/). The [panel and service upgrade page](https://deckerbostonknobandtube.com/electrical-panel-upgrade/) explains when the new circuits outgrow what’s there.

## Cambridge ISD permits and what they cost

The Electrical/Wiring Division of the Cambridge Inspectional Services Department, at 831 Massachusetts Avenue, issues electrical permits through the city’s online system, with its own inspectors. Its posted fees are set per item.

| Item | Fee |
| --- | --- |
| 15 amp receptacle | $1 each |
| 20 amp receptacle | $4 each |
| 30 amp dryer circuit | $5 |
| 50 amp range or water heater | $8 |
| Service, per 100 amps | $10 |
| Meter | $5 each |
| Reinspection for a code violation | $50 |

The posted schedule lists no base application fee or lighting-outlet line, so the electrician confirms the full fee with ISD at 617-349-6100. Work started before a permit triples the fee.

## Historical Commission certificates

The Cambridge Historical Commission oversees two historic districts, Old Cambridge and Fort Washington, and four neighborhood conservation districts: Avon Hill, Half Crown-Marsh, Harvard Square and Mid Cambridge.

Interior alterations and work not visible from any public way are exempt from review, and staff usually issue a Certificate of Non-Applicability for them on the spot. A new meter, mast or exterior conduit visible from the street is the kind of change that goes to review. The Commission says a certificate is always needed for a building permit in a district or on a landmark, so check the address first. The [historic district guide](https://deckerbostonknobandtube.com/guide/rewiring-a-house-in-a-boston-historic-district/) covers the design side.

## From certificate to final inspection

Most Cambridge jobs move through the same steps, and where insulation is planned, its date is the deadline they work back from.

- **The first visit** starts at the panel, traces every circuit, and checks the attic and basement routes.
- **The written scope** names each new circuit, each old run left disconnected, the openings, the panel, and patching as its own line.
- **Any Historical Commission certificate the address needs comes first;** then the licensed electrician files with Cambridge ISD.
- **Work goes area by area,** with planned power-off windows that keep the boiler or furnace controls powered, and notice to other households in a multi-family.
- **Rough-in inspection, then disconnect and test:** old circuits are taken out of service, and reachable attic and basement runs are removed before walls close.
- **The finish** is a labeled panel schedule and a written summary that no knob and tube remains in service, plus the licensed-electrician paperwork Mass Save asks for.

Insulation waiting on old wiring?

Start with which areas the insulation plan covers and which circuits run through them.

Get an Estimate

(617) 405-3599

## Between Fresh Pond and the river

The city is small, but the houses that carry most of this work sit in a fairly clear band.

North of Harvard Yard, Baldwin and Neighborhood Nine run up Massachusetts Avenue toward Porter Square on the Red Line. Baldwin has the city’s highest rate of knob and tube permits, nearly 32 per 1,000 electrical permits. West Cambridge, around Brattle Street, Longfellow House and out toward Fresh Pond, has the second-highest count across all years, 33 permits since 2018, behind Baldwin’s 44.

North Cambridge, out toward Route 2 and the Alewife Brook Parkway, logged 15 in the last five years and Mid-Cambridge 13. Cambridgeport, near Memorial Drive, shows far fewer for its size, about 4 per 1,000, and East Cambridge none.

The calendar matters too. Boston-area winters average 91.6 days at or below freezing (NOAA), and insulation planned for fall or winter puts the electrical certification on a deadline. Cambridge is Eversource territory, so Mass Save’s [barrier incentive and HEAT Loan](https://deckerbostonknobandtube.com/guide/knob-and-tube-removal-grants-massachusetts/) apply. The [Boston-area cost guide](https://deckerbostonknobandtube.com/guide/knob-and-tube-replacement-cost-boston/) shows what moves the price.

## Neighborhoods, landmarks and routes

- Agassiz-Baldwin
- West Cambridge
- Mid-Cambridge
- North Cambridge
- Neighborhood Nine
- Cambridgeport
- Strawberry Hill

### Landmark districts

- Old Cambridge Historic District
- Fort Washington Historic District
- Avon Hill Neighborhood Conservation District
- Half Crown-Marsh Neighborhood Conservation District
- Harvard Square Neighborhood Conservation District
- Mid Cambridge Neighborhood Conservation District

### Landmarks

- Harvard Yard
- Brattle Street
- Fresh Pond
- Longfellow House

### Routes

- Massachusetts Avenue
- Route 2 / Alewife Brook Parkway
- MBTA Red Line (Harvard, Porter, Davis edge)
- Memorial Drive

1. 1. Back Bay, Beacon Hill & South End
2. 2. Belmont
3. 3. Brookline
4. 4. Cambridge
5. 5. Dorchester
6. 6. Jamaica Plain, Roslindale & West Roxbury
7. 7. Medford and Malden
8. 8. Newton
9. 9. Somerville

Schematic, not to scale: close-together neighborhoods are spread out so each number reads.

Planning a rewire in Cambridge?

Start with which circuits are still live. The rest of the estimate follows from that.

Get an Estimate

(617) 405-3599

## Cambridge questions

### Is knob and tube replacement more expensive in Cambridge than in Boston?

There is no separate Cambridge price band. A typical Boston-area budgeting range of $8,000 to $25,000 or more covers replacing the active circuits in a single-family house or one building, and it applies here as it does across the river. What differs is local: Cambridge's per-device permit fees, and any Historical Commission step for visible exterior work. One unit or the common areas alone is priced from its own circuit map.

### Does the Cambridge Historical Commission need to approve an interior rewire?

Interior alterations are exempt from review in Cambridge's districts. The Commission still says one of its certificates is always needed to obtain a building permit for work in a district or on a landmark, and for exempt work that is a Certificate of Non-Applicability, usually issued by staff on the spot. Whether an electrical-only job needs one is confirmed per address. Visible service work goes to review.

### Who inspects knob and tube replacement in Cambridge?

The Electrical/Wiring Division of the Cambridge Inspectional Services Department, not Boston's ISD. A licensed electrician files the permit through the city's online system. Under state rules, new wiring can't be covered until the inspector has seen it, within 72 hours of notice, weekends and holidays excluded, so plaster patching waits for the rough-in inspection.

### Can one condo in a Cambridge two-family be rewired without touching the other unit?

Usually, as long as the circuits being replaced belong to that unit alone. Tracing confirms it, because shared basements, stair lighting and old splices sometimes cross unit lines. Where the panel or service has to change, or a common-area circuit feeds both units, the other owner and the shared spaces come into the scope.

### Is there a Cambridge program that helps pay for electrical repairs?

The City of Cambridge Home Improvement Program offers low-cost, low- or no-interest financing and technical help to income-eligible owners of 1 to 4 family properties, and electrical systems are among the work it lists. The program manages its own bids, so check with it before choosing a contractor. Mass Save's barrier incentive and 0% HEAT Loan also apply in Cambridge, which is Eversource territory.

## Related guides

Decision Guide

Are there grants for knob and tube removal in Massachusetts?

True grants are rare. The real help runs through Mass Save's insulation programs and a few city and state loans, and the order you apply in matters as much as which one you pick.

Learn

How can you tell if knob and tube wiring is live?

A cut end in the attic, a dusty run in the basement, a previous owner's promise: none of them proves the old wiring is dead. What it takes to know, and why the proof should be on paper.

Learn

What changes when you rewire a historic home in Boston?

District commissions care about what the street can see, so most of a rewire never reaches them. The parts that do are the meter, the mast and the conduit, and inside, the plaster and trim are yours to protect.

Cost Guide

How much does knob and tube replacement cost in Boston?

The range Boston-area owners budget with, the handful of things that push a house toward either end, and the public figures sitting inside every price.

## Nearby service areas

Somerville Inspectional Services Department permits

Somerville

Upstairs is original, downstairs isn't

Town of Belmont inspector of wires permits

Belmont

A gas-heated house stopped at the insulation step

Boston Inspectional Services Department permits

Back Bay, Beacon Hill & South End

A condo sale turned up old wiring