# Knob and Tube Replacement in Boston, MA > Knob and tube replacement in Boston: inspection, removal and rewiring by licensed contractors, with local costs, permit rules and Mass Save barrier help. URL: https://deckerbostonknobandtube.com/ ## What usually brings knob and tube to the surface Most people find out about their wiring from someone else. Each of these starts in a different place and needs a different first document. ### Your insurer wants an answer A carrier asks about knob and tube at purchase or renewal, and homeowners report short deadlines to remove it or prove it isn't live. #### The first document to get An electrician's written report on which circuits are active, then a scoped plan to replace them. No one can promise acceptance, but a clear record answers the question being asked. Read more ### A Mass Save assessment stopped your insulation The energy specialist spotted knob and tube, so attic and wall insulation can't go in yet. #### What unblocks it A licensed electrician certifies the work areas are free of active knob and tube, by disconnecting dead runs or rewiring live ones. Income-qualified households can get help with the cost. Read more ### You're buying or selling an older house A home inspector noted porcelain knobs in the basement, and now a closing date sets the pace. #### Closing the gap A home inspection can't trace circuits. An electrician's assessment turns "some K&T seen" into a defined scope with a budget, ideally before the inspection period ends or the house is listed. Read more ### A renovation opened the walls Demolition for a kitchen, bath or attic project exposed old conductors on knobs, sometimes still live and feeding rooms beyond the remodel. #### Use the open walls Open framing is the cheapest moment to replace them, as long as the electrical work and the rough-in inspection come before insulation and new walls. Read more ## Knob and tube services offered through this site Decker Boston Knob and Tube offers and manages knob and tube work across Boston, Cambridge, Somerville and nearby cities. Licensed and insured electrical contractors carry out every job, from a first inspection to a whole-building rewire. ### [Knob and tube inspection](https://deckerbostonknobandtube.com/knob-and-tube-inspection/) A knob and tube inspection booked through Decker Boston Knob and Tube answers three questions before anyone prices a rewire: where the old wiring is, which circuits are still live, and what condition they are in. A licensed electrician does the inspection and puts the findings in writing. #### Why this visit comes first Most calls start with someone else's finding. A home inspector notes porcelain knobs in the basement, an insurer asks about the wiring, or a Mass Save energy specialist stops insulation. None of those visits traces circuits, so none of them can say whether the knob and tube is active, abandoned, or spliced into later cable. #### What the electrician checks The electrician reviews what can be seen safely in the attic, basement and panel, maps circuits back to their fuses or breakers, and looks for brittle insulation, buried splices, oversized fuses and insulation packed against old conductors. Runs sealed inside finished plaster can't be confirmed without access, and the written report says so plainly. #### What sets the price and what you receive There is no flat figure because the visit varies: the number of dwelling units, how many circuits leave the panel, attic and basement access, and whether the report has to satisfy an insurer, a buyer or a Mass Save certification. You get findings by room and circuit and a recommended scope. Knob and tube inspection: scope, process and costs What the written findings should record - Which circuits are active knob and tube, abandoned, or mixed with later cable - Rooms and spaces checked, and the areas that could not be seen - Fuse or breaker sizes compared with the wire they protect - Insulation in contact with old wiring in the attic or walls - Panel condition, capacity and spare spaces - A recommended scope: targeted repair, partial replacement or a whole-house rewire ### [Knob and tube removal](https://deckerbostonknobandtube.com/knob-and-tube-removal/) Removal takes knob and tube out of service for good: disconnecting it at the source, replacing what it fed, and pulling out the runs that can be reached. Decker Boston Knob and Tube arranges removal with licensed and insured electricians, on its own or as part of a larger rewire. #### Disconnected is not the same as gone A circuit cut at the panel can still be live if someone spliced it to a newer circuit in a ceiling box. Before old wiring is called dead, the electrician traces each run, de-energizes it, and confirms at the far end that nothing else still feeds it. #### What actually comes out Exposed runs in unfinished attics, basements and crawl spaces can usually come out entirely, knobs, tubes and loom included. Sections sealed inside finished plaster are usually cut back, capped and left in place, because tearing them out would mean opening walls for no electrical benefit. The plan for each run is agreed before work starts. #### Why the record matters The City of Boston's guidance says insulation can proceed once knob and tube is inactive, and insurers ask whether it is still in use. So the useful product of removal is a clear record: which runs were removed, which were abandoned in place, and confirmation that none of them remain energized. ##### Abandoned in place Disconnected at both ends, verified dead and left inside closed walls. Less cost and disruption, and the usual approach where the wiring can't be reached without opening finished plaster or ceilings. ##### Physically removed Pulled out with its knobs, tubes and loom wherever it is exposed. The norm in attics before insulation and in basements, where leftover wire confuses the next electrician, inspector or buyer. Knob and tube removal: scope, process and costs ### [Whole-house rewiring](https://deckerbostonknobandtube.com/whole-house-rewiring/) Whole-house rewiring replaces every branch circuit, not only the knob and tube, so the house ends up on one modern system with a single circuit map. Decker Boston Knob and Tube arranges it through licensed and insured electricians when old wiring is spread across most rooms or mixed with cloth and early armored cable. 72 hours The longest the inspector of wires may take after notice, weekends and holidays excluded, before new wiring can be covered (527 CMR 12.00, Rule 10) #### When it beats piecemeal work If a house holds knob and tube, cloth-sheathed cable and old armored cable together, replacing only the K&T leaves other aging wiring behind closed plaster. A full rewire also lets the layout follow how the house is used today, with dedicated kitchen and bath circuits and more outlets in bedrooms. #### How the work is sequenced Electricians plan new routes through attics, basements, closets and chases, shut down one area at a time, run new cable and boxes, and land each circuit on an AFCI breaker, which Massachusetts requires on every 10, 15 and 20 amp, 120-volt circuit in a home. Openings stay open until the inspector has seen the rough-in. #### Decisions you'll make You choose where outlets and lights go, whether the panel or service needs to grow, and who patches: the electrical contractor, a plasterer you hire, or you before painting. Plaster restoration and painting are a separate scope from the electrical work, so confirm in writing who does them and to what finish. Whole-house rewiring: scope, process and costs ### [Partial knob and tube replacement](https://deckerbostonknobandtube.com/partial-knob-and-tube-replacement/) Partial replacement takes out the knob and tube left after earlier updates, or one floor or group of rooms at a time. Through this site, licensed and insured electricians define the boundary of the old system first, then replace every circuit inside it from the panel to the last device. #### Where it fits It suits houses where a kitchen, bath or basement was rewired years ago and a few original circuits still feed bedrooms or ceiling lights. Boston permit descriptions show the pattern, with jobs written up as rewiring the outlets and lighting still served by knob and tube, or demolishing one old circuit and rewiring a single unit. #### Doing it properly The risky version replaces only what is visible in the basement and leaves live runs in the walls. A proper partial job traces every circuit that still touches knob and tube, replaces it end to end, and documents what remains so nobody later assumes the house is clear. #### Planning the next phase Phasing the work around a budget or a renovation works when each phase leaves clean junction points in accessible boxes, a labeled panel and a written list of the old circuits still in service. The next stage then starts from known conditions instead of a fresh investigation. #### What the handover records Each replaced circuit runs in new cable from the panel to every device, lands on an AFCI breaker and is labeled at the panel. Remaining knob and tube is listed in writing by room and circuit, and splices to newer wiring sit in accessible boxes, never buried in a wall. Partial knob and tube replacement: scope, process and costs Also covered in depth #### Old circuits spliced into newer cable A mixed system is one where knob and tube and modern NM cable, usually called Romex, share circuits, the typical result of renovations and selective rewiring. ##### Where the risk sits The weak point is the connection: newer cable spliced to old conductors in a ceiling box or, worse, with no box at all inside a wall. Modern cable at an outlet doesn't prove the circuit is modern upstream, so tracing it end to end is the only way to know how much is old. ##### What Massachusetts code allows Existing wiring may stay in service when a circuit is modified, but under 527 CMR 12.00 Rule 3 the change may not create a violation or make an existing one worse. That is why the splice point, where old meets new, gets the closest look during an assessment. Read the full guide #### Replacing some of it or all of it Whether to replace part of the knob and tube or all of it depends on how much remains, its condition, and what the work has to prove. ##### What drives the decision Massachusetts code doesn't order working knob and tube out of a house, so the pressure usually comes from an insurer, a Mass Save insulation plan or a sale. Homeowners report insurers asking whether all of it is gone, and a partial job can't honestly answer yes until its last phase. ##### Which way it tends to go Partial makes sense when a few circuits remain and the rest of the wiring is sound. Whole-house makes sense when old wiring is widespread, mixed with cloth or early armored cable, or the panel is being replaced anyway, since one permit sequence then covers everything. Read the full guide ### [Insulation barrier work](https://deckerbostonknobandtube.com/knob-and-tube-insulation-barrier/) When a Mass Save Home Energy Assessment finds knob and tube, insulation stops until a licensed electrician deals with it. Decker Boston Knob and Tube arranges that barrier work, from verification to disconnection and rewiring, so the weatherization the assessment recommended can go ahead. #### Why insulation has to wait Knob and tube was designed to shed heat into open air around separated conductors, and packing insulation around it traps that heat. Massachusetts adopts the NEC's knob and tube article unchanged, and Mass Save's standards treat any evidence of it as a barrier to insulating the whole home, except open cavities where the specialist can see there is none. #### What the electrician must provide The standard asks a licensed electrician to certify that the areas slated for insulation, or for air sealing that could touch the wiring, are free of active knob and tube. Depending on what the trace finds, that means disconnecting dead runs or rewiring the circuits still live in the attic floor and exterior walls. #### Scope and timing The certification covers the work areas, not necessarily the whole house, so the scope can be one attic or every exterior wall. Air sealing, duct sealing and pipe insulation may continue if the old wiring stays undisturbed. Schedule the electrical work first, because the certification has to exist before insulation goes in. Insulation barrier work: scope, process and costs Pre-1955 Houses in which Mass Save's assessment standards say knob and tube should always be suspected Also covered in depth #### Help paying for barrier work Most help with the cost of knob and tube removal in Massachusetts runs through the insulation programs, and household income decides which one fits. ##### Mass Save incentive and loan Moderate-income households in a one- to four-unit home can receive up to $7,000 of eligible removal costs, paid upfront as two checks, to you and to the contractor, with income verification and a licensed electrician's signed proposal. After a Home Energy Assessment, the HEAT Loan adds 0% financing for barriers within a $25,000 lifetime cap. ##### Boston's own program In Boston, the Boston Home Center's Home Repair and Improvement Loan, a deferred 0% loan of up to $50,000 for income-eligible owner-occupants, lists knob and tube removal among the work it covers. Read the full guide Plaster stays up; small access openings are patched after inspection. ### [Plaster wall rewiring](https://deckerbostonknobandtube.com/plaster-wall-rewiring/) Rewiring a plaster-and-lath house doesn't have to mean gutting it. Through Decker Boston Knob and Tube, licensed and insured electricians plan routes that use the house's own cavities, keep openings small, and leave you with a clear, written patching scope. #### Why plaster changes the job Plaster on wood lath is hard, brittle and locked to the lath by keys pushed through the gaps. Careless cutting cracks the wall around the hole, and finishes such as cornices, picture rails and painted trim are hard to match. Every opening carries a restoration cost, so the route plan matters more here than in a drywall house. #### How new cable gets through Massachusetts code allows cable to be fished between access points in finished buildings, and treats cable run behind ceiling strapping as supported. Electricians feed runs from the attic down and the basement up, through closets and behind baseboards, cutting small, neat holes at boxes and top plates only where a straight path is blocked. #### Patching and lead-safe rules Settle who patches before work starts. In a house built before 1978, disturbing more than six square feet of painted surface per room makes the job lead-safe renovation work under Massachusetts rules, which changes the setup and the cost, so the access plan affects more than the plaster bill. ##### Fish through access holes New cable pulled through existing cavities with small cuts at boxes, plates and blocked bays. Least plaster damage, but slower where framing or fire blocking gets in the way. ##### Open selected walls Longer openings along a run, used where cavities are blocked or a renovation is opening walls anyway. Faster routing, more patching, and lead-safe rules more likely to apply. Plaster wall rewiring: scope, process and costs Also covered in depth #### Lead paint, asbestos and old attic fill Knob and tube conductors are generally insulated with rubber and cloth, but whether any material in a house contains asbestos is settled by testing, not by looking. ##### The lead-paint rule Massachusetts treats housing built before 1978 as target housing. Work that disturbs more than six square feet of painted surface per room, or partly demolishes painted surfaces, must be done as lead-safe renovation by a licensed lead-safe renovation contractor unless testing shows no lead. ##### What it means for the plan Fishing cable through small holes can stay under that threshold; opening walls usually won't. Vermiculite attic fill is a separate problem, and Mass Save's barrier incentive covers vermiculite as well as knob and tube. 6 sq ft Painted surface per room above which work in a pre-1978 home becomes lead-safe renovation work Read the full guide #### What historic district review covers Boston's local historic districts review exterior work, not the wiring inside your walls. ##### What triggers review In Back Bay, Beacon Hill, the South End, Bay Village, St. Botolph and the other Landmarks Commission districts, a new meter, service mast or conduit visible from a public way needs a design decision before the building permit. Inside, the concern is historic plaster, trim and ceilings, which a careful fishing plan protects. ##### Back Bay goes further Its residential guidelines add specific rules for service equipment on top of the general review. Back Bay residential guidelines - No electrical equipment on primary elevations - Wiring and equipment in black - Building attachments between the first and second story on the rear - Every unit connection made inside the building - No exposed conduit Read the full guide Rowhouses, brownstones and triple-deckers share the same multi-unit questions. ### [Triple-deckers, condos and multi-family](https://deckerbostonknobandtube.com/triple-decker-rewiring/) Decker Boston Knob and Tube arranges knob and tube replacement in triple-deckers, two-families, condos, brownstones and rowhouses, including occupied units and common areas. Licensed and insured electrical contractors do the work, staged so each household keeps power for as much of the job as possible. #### Why multi-unit jobs are different Boston has 23.5% of its homes in three- and four-unit buildings, against 4.3% nationally, and its wood-frame triple-deckers date from the same decades as knob and tube. A whole-building rewire means several units, often several meters, hallway and stair lighting, and people living on every floor. #### Common areas and panels Massachusetts lets common-area lighting on the same floor of an existing three-family house be fed from a unit's panel instead of a separate house panel, which simplifies hallway rewiring. Permit records in Boston, Cambridge and Somerville show multi-unit knob and tube work paired with a new sub-panel for each unit. #### Condos, brownstones and rowhouses In a masonry rowhouse or brownstone converted to condominiums, the job is usually one unit inside a shared building. In buildings over three stories above grade, Massachusetts keeps NM cable circuits on the floor or unit where they start, which can call for other wiring methods. Check the condo documents for rules on shared walls and basement access. #### Staging around the people living there Each unit is rewired in turn with its own power-off windows, and hallway and stair lighting is traced and replaced as a separate scope. Occupants get notice and access is scheduled unit by unit, so no household is without power for the whole job. Triple-deckers, condos and multi-family: scope, process and costs ### [Fuse box and panel upgrades](https://deckerbostonknobandtube.com/electrical-panel-upgrade/) Replacing a fuse box with a breaker panel, or a 60 or 100 amp service with a larger one, often comes up during knob and tube work. Decker Boston Knob and Tube arranges panel and service upgrades alongside the rewire, done by licensed electricians, with the utility's part of the job coordinated. #### Why the panel comes up Every new circuit needs arc-fault protection, so an old fuse panel or a full breaker panel can simply run out of room. Fuses also invite overfusing, where a larger fuse goes into a circuit whose wire can't carry the extra current. That is one of the conditions an assessment looks for before deciding the panel's future. #### What a service upgrade involves A service upgrade replaces the meter socket, service-entrance conductors and main panel, and it involves the utility: Eversource in Boston, Cambridge, Somerville, Brookline and Newton, National Grid in Medford and Malden, and the town's own Belmont Light in Belmont. Inside a historic district, visible exterior equipment needs design review first. #### Choosing the size The size comes from a load calculation, not habit. Heat pumps, induction cooking and EV charging push toward 200 amps; a house staying on gas heat with modest loads may only need a new panel on its existing service. The decision changes cost, so make it before the circuit layout is final. Fuse box and panel upgrades: scope, process and costs On an existing one- or two-family house, the Massachusetts version of the outdoor emergency disconnect rule generally doesn't apply when only the meter socket, service conductors, main breaker or related raceways are replaced. The inspector confirms which requirement applies at each address. Also covered in depth #### Budgeting for a new panel and service Upgrading a fuse box to a 200 amp breaker panel together with the service work falls in a typical Massachusetts range of $3,000 to $6,500. ##### What moves the number A panel-only swap on an adequate existing service costs less, and utility charges are separate. The spread comes from the meter socket and service-entrance cable, an overhead mast or underground feed, where the panel sits, grounding and bonding, and how many circuits move over. Historic districts add a design review step. ##### The permit share The permit is a small part of it. Boston Inspectional Services charges $20 plus $0.25 per amp for a service upgrade, so a 200 amp service at 240 volts carries a $70 fee. Read the full guide #### Why new breakers leave old wiring in place No, a new panel doesn't remove knob and tube. It changes the equipment that protects circuits, not the wire running through the walls. ##### What the code says Massachusetts lets a service or panel be replaced without replacing existing knob and tube circuits. 527 CMR 12.00 Rule 3 says additions and modifications don't force the rest of an installation into compliance, and the state's interpretation committee has confirmed that reading for services feeding knob and tube. ##### Why pairing them still makes sense In Boston's permit data, 25 of the 79 permits that name knob and tube also mention a service or panel: one permit sequence, with new circuits landing on new breakers. A panel alone doesn't answer an insurer's or Mass Save's question, because the old circuits are still there. Read the full guide ### [Ungrounded outlet upgrades](https://deckerbostonknobandtube.com/ungrounded-outlet-upgrade/) Two-prong outlets, and three-prong outlets with no ground behind them, are the everyday face of knob and tube. Decker Boston Knob and Tube arranges grounding upgrades and outlet replacement through licensed electricians, matched to whether each circuit should be kept or replaced. #### Why the outlets have no ground Knob and tube carries two conductors, hot and neutral, and no equipment grounding conductor. That is the original design, not a later defect. A three-prong outlet swapped onto that circuit looks modern but has nothing connected to its ground terminal, so surge strips and appliance frames plugged into it have no fault path. #### Ways to fix it Where the circuit is modern but ungrounded, the options are running a grounded cable to the outlet or adding protection that cuts power on a fault. Where the circuit is knob and tube, running new grounded cable usually means replacing the circuit itself, which is why an outlet upgrade on knob and tube usually becomes a partial rewire. #### What testing shows A plug-in tester reads open ground on most of these outlets, but it can be fooled by a bootleg ground, where the neutral is jumpered to the ground screw. The electrician opens the box, checks what is actually connected and traces the circuit before recommending a fix. #### What a three-prong outlet doesn't prove It doesn't prove a ground wire is connected behind it, that the circuit is modern cable all the way to the panel, that a jumper isn't faking the reading, or that the outlet has GFCI or AFCI protection. Each of those is checked, not assumed. Ungrounded outlet upgrades: scope, process and costs Also covered in depth #### Ground-fault and arc-fault protection on old circuits GFCI and AFCI devices guard against different failures, and neither one repairs brittle insulation or a buried splice. ##### What each device does A GFCI trips when current leaks away through water or a person. It works without a ground wire, so it adds shock protection to a two-wire circuit without creating a ground. An AFCI watches for arcing, the signature of damaged insulation and loose splices. ##### What Massachusetts requires AFCI protection on every 10, 15 and 20 amp, 120-volt circuit supplying outlets or devices in a home, and GFCI for receptacles within six feet of a sink or inside a sink cabinet. The state also deleted the NEC subsection on retrofitting ground connections, so any keep-and-protect plan is confirmed with the inspector. Read the full guide ### [Cloth wiring replacement](https://deckerbostonknobandtube.com/cloth-wiring-replacement/) Cloth wiring is any old wiring whose conductors are wrapped in rubber and woven fabric, whether laid out as knob and tube or bundled in a cloth-covered sheath. Decker Boston Knob and Tube arranges its replacement through licensed and insured electricians, judged circuit by circuit on condition rather than age alone. #### Why the insulation fails Rubber insulation hardens and cracks with age and heat, and the cloth over it frays. Where wire bends into boxes, sits above hot light fixtures or was disturbed by later work, the conductor can end up bare. Terminations take the most stress, so an outlet or fixture box is a common place for damage to show. #### What replacement involves Cloth-sheathed cable runs like modern cable, stapled along framing and into boxes, so new cable can often follow the same paths with little extra access. The scope includes larger boxes where old ones are too small for modern devices, grounded outlets, AFCI breakers, and a decision on any old metal-armored cable found alongside it. #### How to decide what goes first Not all cloth wiring has to go at once. Wiring that is intact, unmodified and away from heat and insulation can wait for a planned rewire; brittle sheathing at fixtures, scorched boxes, or cloth cable spliced into knob and tube should move to the top of the list. An inspection sorts the two. Cloth wiring replacement: scope, process and costs Also covered in depth #### Telling knob and tube apart from cloth-sheathed cable Both use rubber and cloth insulation, and early versions of both lack a ground wire, but they are laid out differently and judged differently. ##### How to tell them apart Knob and tube runs hot and neutral on separate paths, held off the framing by porcelain knobs and passed through joists in porcelain tubes, with loom where it enters a box. Cloth-sheathed cable bundles both conductors in one fabric jacket and is stapled to framing like modern cable. ##### Why the difference matters Knob and tube depends on open air to stay cool, which is why insulation over it is the barrier Mass Save names; cloth cable is judged mainly on its sheathing. Old armored cable, often called BX, is a third type, with a metal jacket that sometimes served as the only ground path. Read the full guide ### [Rewiring during a remodel](https://deckerbostonknobandtube.com/knob-and-tube-remodel-rewiring/) A kitchen, bath or attic renovation is the cheapest moment to replace knob and tube, because the walls are already open. Decker Boston Knob and Tube arranges the electrical side through licensed and insured electricians, sequenced with your general contractor or designer so the walls close only once. #### Why timing matters Open studs and joists let new cable run straight to its boxes, with no fishing and no extra patching. Once plaster or drywall goes back, the same work costs access and restoration. Old circuits exposed by demolition can feed rooms well beyond the remodel, so the real scope question is where those circuits go. #### Inspection before the walls close In Massachusetts, new wiring can't be covered until the inspector of wires has seen it. Build the rough-in inspection into the schedule so insulation and drywall crews aren't waiting on an inspection nobody booked, and so old wiring found late doesn't end up sealed behind new walls. #### Scope decisions Decide early whether the project replaces only the circuits in the remodeled rooms or follows knob and tube back through the rest of the house while access is easy. New kitchen and bath circuits also need panel space for AFCI and GFCI protection, so check the panel before the layout is final. Rewiring during a remodel: scope, process and costs Before the walls close - Trace every old circuit exposed by demolition to where it starts and ends - Disconnect and remove dead knob and tube in the open bays - Confirm panel space for the new circuits - Book the rough-in inspection - Record in writing any knob and tube left beyond the remodel ## What knob and tube work costs around Boston These are budgeting ranges to plan with, not quotes or company rates. Each row says what the range covers and what moves a job up or down within it. Whole-house knob and tube replacement $8,000 to $25,000 or more What it covers A typical Boston-area budgeting range for replacing the active knob and tube circuits in a single-family house or one building with new cable, devices and protection. Plaster restoration and service upgrades are usually extra. What moves the price Active circuit count, stories and layout, attic and basement access, plaster versus drywall, patching and painting, and panel or service changes. Panel or service upgrade alongside the rewire $3,000 to $6,500 What it covers A typical Massachusetts range for a fuse box or small service upgraded to a 200 amp breaker panel with service work. A panel-only swap costs less; utility charges are separate. What moves the price Meter and service-entrance changes, overhead or underground feed, panel location, grounding and bonding, and design review in historic districts. Partial replacement Priced from the assessment What it covers The circuits left after earlier updates, or one floor or one unit at a time. What moves the price How many circuits still touch knob and tube, how far they run from the panel, access to them, and whether junctions with newer wiring need new boxes. Inspection and written findings Priced from the assessment What it covers Circuit tracing and a written report for an insurer, a buyer or a Mass Save certification. What moves the price Number of units, circuit count, attic and basement access, and the kind of document the report has to support. Plaster restoration and painting depend on the finish and on whether lead-safe rules apply in a pre-1978 house, so they are priced from the access plan. The cost estimator shows how your house's details move these ranges. [Try the cost estimator](https://deckerbostonknobandtube.com/tools/knob-and-tube-cost-estimator/) ## Repair, partial or whole-house: choosing the scope There is no universal answer. The right scope depends on how much knob and tube is active, the condition of everything around it, and what the work has to prove to an insurer, a buyer or Mass Save. ### Targeted repair or abandoning dead runs When it fitsOnly a few knob and tube runs remain, they are already dead or feed one or two loads, and the rest of the wiring is modern and sound. TradeoffsLowest cost and disruption. It doesn't change the picture if live circuits remain elsewhere, and an insurer asking whether all knob and tube is gone needs a clear written answer. ### Partial replacement When it fitsEarlier updates covered most of the house and a defined set of original circuits still serves some rooms, or the budget calls for phases. TradeoffsSpreads the cost and keeps patching local. It requires tracing every remaining circuit and documenting the boundary, and leftover old circuits keep insurance and insulation questions open until the last phase. ### Whole-house rewiring When it fitsKnob and tube runs through most rooms, is mixed with cloth or early armored cable, or the panel and service are being replaced anyway. TradeoffsHighest upfront cost and the most access work, but one permit sequence, one circuit map and no old wiring left to explain to an insurer, a buyer or Mass Save. ## How a knob and tube job runs from first call to sign-off ### First call Tell us what prompted the call, the town and type of building, how many units it has, and any deadline from an insurer, a sale or an insulation contractor. Photos, an inspection report or a Mass Save assessment help route the job to the right licensed electrician. ### Assessment The electrician reviews the panel and the accessible attic and basement wiring, traces circuits, and notes which knob and tube is active, abandoned or mixed. You receive written findings and a scope, with access, patching and permit items listed separately. ### The work The licensed contractor files the permit, then works area by area so the rest of the house keeps power. New cable is fished or run through open framing, the rough-in is inspected before walls close, and old circuits are disconnected and removed where reachable. ### Completion Circuits are tested and labeled at the panel, the final inspection closes the permit, and you get the records: what was replaced, what was abandoned in place, and any knob and tube that remains. Those papers answer insurers, buyers and Mass Save. ## What else this site covers about knob and tube Each topic below has its own in-depth guide. Here is the short version of each, with the local figure or rule that matters most. ### How the old wiring works and fails #### The wiring system behind older Boston plaster Knob and tube is an early wiring method: single conductors in rubber and cloth, held on porcelain knobs, passed through porcelain tubes, cooled by open air, with no ground wire. ##### Where it turns up Mass Save's assessment standards say it should always be suspected in houses built before 1955, and the inner core is full of them: Somerville has 59.0% of its housing built before 1940, Belmont 57.1% and Brookline 51.7%. ##### Why it causes trouble now The design suited the light loads it was built for. The trouble is age, later splices, insulation added around it, and modern demand on circuits that were never planned for kitchens full of appliances or rooms full of electronics. Read the full guide #### Spotting it in an attic, basement or outlet The clearest evidence is in unfinished spaces, and the hints in finished rooms prove much less than they seem to. ##### Attics and basements Look for porcelain knobs nailed to joists or rafters with single wires wrapped around them, and porcelain tubes where wires pass through framing, usually in a basement ceiling or across an attic floor. Photograph it, but leave the wiring alone, since old insulation can crumble when handled. ##### Finished rooms Two-prong outlets, old push-button switches and ceiling fixtures on shallow boxes are hints, not proof. A three-prong outlet doesn't prove a circuit isn't knob and tube, because old circuits can be extended with newer cable. An electrician confirms by tracing circuits from the panel. Read the full guide #### Live, dead or somewhere in between You can't tell whether knob and tube is live by looking at it, and testing it isn't a homeowner job. ##### How an electrician checks Wiring that looks abandoned may still connect, through a splice, to a circuit added later. The electrician checks with a non-contact tester and a meter, then traces each run to the panel or the splice that feeds it, switching circuits off one at a time to see what goes dead. ##### Why the answer matters The City of Boston's guidance says insulation can proceed once knob and tube is inactive, and Mass Save asks a licensed electrician to certify that the areas being insulated are free of active wiring. Read the full guide #### How much risk old wiring really carries Knob and tube isn't automatically dangerous, but it has little margin for the ways houses change. ##### What raises the risk Brittle insulation that exposes conductors, splices added inside walls without boxes that can arc, insulation packed around wires that rely on open air to cool, and fuses swapped for larger ones so a circuit carries more than its wire safely can. There is also no ground, so no fault path for shocks. ##### How it gets judged Intact, unmodified wiring that is clear of insulation and on correctly sized fuses can stay in service. Which conditions are present can't be judged from inside a room; it takes an inspection of the accessible wiring and a circuit trace. Read the full guide #### Symptoms that point toward a rewire No single symptom names a cause; a flicker can come from a loose fixture connection as easily as from old wiring. Some signs still deserve prompt attention. ##### Call an electrician promptly An outlet or switch plate that feels warm, a burning smell, scorch marks, buzzing at a device, or a fuse or breaker that keeps tripping on the same circuit. ##### Signs of an undersized system Lights that dim when an appliance starts, two-prong outlets, few outlets per room and extension cords everywhere. A house built before 1940 that still has its original fuse panel and no record of rewiring is worth an inspection even without symptoms. Read the full guide #### How much load an old circuit can take There is no single amp rating for knob and tube. What a circuit can carry depends on wire size, condition, surrounding insulation and, above all, the fuse or breaker protecting it. ##### Where demand outgrows it A circuit laid out for a few lights and outlets may now run space heaters, window air conditioners and kitchen appliances. An overloaded circuit runs warm, and an oversized fuse lets it keep running. Services were small too; Cambridge permit records list existing services as small as 60 amps. ##### The fix More circuits and, where needed, a larger service, never a bigger fuse. The fuse or breaker has to match the wire it protects. Read the full guide ### Code, permits and insurance | Topic | What the rule says | What it means for you | | --- | --- | --- | | Where Massachusetts code stands on existing knob and tubeExisting knob and tube is not illegal in Massachusetts; insurers and Mass Save, not the code, are what usually force removal.[Read the full guide](https://deckerbostonknobandtube.com/guide/is-knob-and-tube-legal-in-massachusetts/) | The state electrical code, 527 CMR 12.00, the 2026 NEC with Massachusetts amendments for installations permitted after April 24, 2026, lets work be added without bringing the rest of an installation up to current code, as long as it doesn't create or worsen a violation. The NEC's knob and tube article applies unchanged. | Old circuits may stay, but new work must meet today's rules, and anyone installing wiring for hire must be a licensed electrician who notifies the inspector of wires. | | Permits and inspections for a rewire in BostonEvery knob and tube replacement in Boston needs an electrical permit from Inspectional Services, filed by the licensed contractor before work begins.[Read the full guide](https://deckerbostonknobandtube.com/guide/boston-electrical-permit-for-rewiring/) | Boston Inspectional Services charges a $20 application fee plus, when the service doesn't change, $1 per fixture, plug or outlet and $5 per approved meter. Starting work before the permit is issued can mean double the cost. The inspector checks the rough-in before walls close and the finished work afterward. | The fee follows the device count, so it is small next to labor. Cambridge, Somerville, Medford and the other nearby cities run their own wire offices and fees, so a house across the line is permitted there, under the same state code. | | Insurance questions about old wiringThe state electrical code doesn't require knob and tube removal; the pressure comes from insurers' own underwriting.[Read the full guide](https://deckerbostonknobandtube.com/guide/knob-and-tube-insurance-massachusetts/) | There is no code deadline, but homeowners report carriers asking about knob and tube and fuses at purchase or renewal, some setting 30 to 60 days to remove it or show it isn't live. The Massachusetts Property Insurance Underwriting Association, the state's FAIR Plan, inspects interior systems including wiring before it writes a policy. | Documentation helps: an electrician's written report on which circuits are active, then a permit and completion record once the work is done. No contractor can promise that a carrier will accept the house afterward. | ### Buying, selling and budgeting #### Before you close on a house with old wiring A house with knob and tube can be a sound purchase if you learn the scope before the inspection period ends. ##### Do before closing Have an electrician trace circuits, since a home inspector can report knobs but not how much is active. With written findings and a typical Boston-area budgeting range of $8,000 to $25,000 or more for a whole house, negotiate a credit or price change, or plan the work for after closing. ##### Watch for Ask early for an insurance quote that names the wiring. Homeowners report carriers setting short deadlines after purchase, with the FAIR Plan as the fallback, and that can squeeze the weeks right after closing. Read the full guide #### Listing a house that still has knob and tube You can sell a Massachusetts house with knob and tube; nothing in the electrical code stops the sale. What you disclose is a question for your agent or attorney. ##### Seller Replace before listing, commission an electrician's written assessment and scope for buyers to see, or price the house with the work in mind. A written report turns a vague inspection note into a defined job with a budget. ##### Buyer Their insurance and financing come first. If you rewire before listing, keep the permit and completion records, since they answer the first question a buyer's insurer is likely to ask. Read the full guide #### What a Boston-area rewire budget looks like Replacing knob and tube in a whole house falls in a typical Boston-area budgeting range of $8,000 to $25,000 or more. ##### Budget for Active circuit count, stories and layout, attic and basement access, plaster versus drywall, patching and painting, and any panel or service change. Electricians in the Boston metro earn a mean $40.08 an hour, about 17% above the $34.37 national mean, according to the U.S. Bureau of Labor Statistics. ##### Watch for Larger, plaster-heavy or service-upgrade jobs can run well past the range. A wage is not a billing rate, which also carries insurance, licensing, vehicles and overhead. Read the full guide #### Reading two rewiring quotes side by side Two quotes for the same house can differ by thousands because they describe different jobs, so line them up on the same points. ##### Compare on Circuits replaced and the rooms they serve, whether all active knob and tube goes or only what is visible, abandoned wire, permit and inspections, AFCI and GFCI protection, panel or service work, and who patches and paints to what finish. In a pre-1978 house, ask whether lead-safe practices are priced in. ##### Red flags Homeowners report quotes that misread the wiring or left dead knob and tube in place to save money. A scope without a circuit-by-circuit list leaves room for both, so ask for it in writing. Read the full guide ### During the work #### How old circuits are swapped for new ones Replacement follows a set order: map, permit, rewire, inspect, then disconnect the old wiring and test, with patching always after the inspection. ##### The sequence The electrician maps every circuit and plans the new layout, then the permit is filed. Work moves area by area: a circuit is de-energized, new cable is fished to each box, old boxes and devices are replaced, and the circuit lands on a new breaker. The inspector of wires checks the rough-in before walls close. ##### Your part Confirm the circuit map, clear access to the attic and basement, agree the patching scope, and keep the final test and label records. Read the full guide #### Staying in the house while it's rewired Living at home through a rewire is usually workable when the job is staged, with one area shut down while the rest of the house keeps power. ##### What to expect Dust at access holes, furniture moved away from walls, and stretches without power in the rooms being worked on. Winter needs planning in Boston, which averages 91.6 days a year with lows at or below freezing. ##### Before work starts List the circuits feeding boiler or furnace controls, the refrigerator and any medical equipment so they stay live or return quickly, and in a two- or three-family house, give each household notice of its own shutoff windows. Read the full guide ## Where knob and tube work is arranged The same state code applies everywhere, but permit offices, utilities, historic review and building types change from one city or neighborhood to the next. Each area page covers what changes there. | Area | Permit and inspection | Electric utility | What changes the job here | | --- | --- | --- | --- | | [Dorchester](https://deckerbostonknobandtube.com/service-areas/dorchester/) | Boston Inspectional Services | Eversource | Boston's densest three-decker belt, where a rewire usually means several occupied units, several meters, and common hallways and stairs as their own scope. | | [Jamaica Plain, Roslindale & West Roxbury](https://deckerbostonknobandtube.com/service-areas/jamaica-plain-roslindale-west-roxbury/) | Boston Inspectional Services | Eversource | Detached and two-family streetcar-era houses that account for most of Boston's permits naming knob and tube, often for the circuits left after earlier partial updates. | | [Back Bay, Beacon Hill & South End](https://deckerbostonknobandtube.com/service-areas/back-bay-beacon-hill-south-end/) | Boston Inspectional Services, plus Landmarks Commission district review | Eversource | Masonry rowhouse condominiums rewired unit by unit, where any meter, mast or conduit change has to clear district design review before permits. | | [Cambridge](https://deckerbostonknobandtube.com/service-areas/cambridge/) | Cambridge Inspectional Services | Eversource | Its own permits and Historical Commission certificates, with knob and tube permits clustered in Baldwin, North, West and Mid-Cambridge, some tied directly to insulation projects. | | [Somerville](https://deckerbostonknobandtube.com/service-areas/somerville/) | Somerville Inspectional Services | Eversource | The inner core's highest share of pre-1940 housing at 59.0%, with floor-by-floor rewires of two-families and triple-deckers concentrated in West Somerville. | | [Belmont](https://deckerbostonknobandtube.com/service-areas/belmont/) | Town of Belmont wiring inspector | Belmont Light | Belmont Light, the town's municipal utility, means your heating fuel decides whether Mass Save's knob and tube rule governs your insulation. | | [Medford & Malden](https://deckerbostonknobandtube.com/service-areas/medford-malden/) | Medford Superintendent of Wires; Malden wire office | National Grid | National Grid territory, so a rewire with a service upgrade follows National Grid's service request process, and Medford's wire office takes inspection requests in set hours. | | [Brookline](https://deckerbostonknobandtube.com/service-areas/brookline/) | Town wire inspector, confirmed per address | Eversource | More than half of homes built before 1940, split between large single-family houses and apartment buildings; historic-district requirements are confirmed per address and project. | | [Newton](https://deckerbostonknobandtube.com/service-areas/newton/) | City wire inspector, confirmed per address | Eversource | Mostly detached pre-war houses, with 54.8% of homes single-family detached; historic-district requirements are confirmed per address and project. | Those pages also cover Roxbury, Mattapan, East Boston, South Boston, Hyde Park, Charlestown, Bay Village and St. Botolph, and the service areas page covers Brighton, Allston, Quincy, Arlington, Everett and Chelsea. [All service areas](https://deckerbostonknobandtube.com/service-areas/) ## Knob and tube questions from Boston-area homeowners ### Who actually does the work when I book through this site? Licensed and insured electrical contractors do the work. Decker Boston Knob and Tube offers and manages knob and tube projects across Boston and nearby cities: taking the first call, arranging the assessment and coordinating the job through the final inspection. The licensed contractor files the permit with the local inspector of wires and is responsible for the electrical work, as Massachusetts law requires. ### Can I replace knob and tube wiring myself in Boston? No. Boston Inspectional Services says a homeowner must hire a licensed contractor to apply for the electrical permit and complete the work, and Massachusetts law requires anyone installing wiring as a business to be licensed. There is a practical reason too: old rubber insulation can crumble when handled, and live circuits hide behind dead-looking ones, so even pulling out old wire is a job for an electrician. ### Will rewiring add outlets and circuits? It can, and it is worth planning that way. Houses wired in the knob and tube era were laid out for lighter loads and fewer outlets. A rewire is the cheapest time to add outlets, split overloaded circuits and give the kitchen, bath and laundry their own, because cable is already being routed. Each new circuit needs a panel space, which feeds into the panel decision. ### What paperwork should I have when the job is finished? Keep the closed permit with the inspector's approval, a labeled panel schedule, and a written summary from the contractor stating which circuits were replaced, which knob and tube was removed or abandoned in place, and whether any active knob and tube remains. Where Mass Save is involved, the electrician's certification for the insulation areas is the document the program needs. ### Do solar panels or a heat pump require removing knob and tube first? Not under the electrical code. The state's interpretation committee has said Rule 3 allows a solar system to be added to a service with knob and tube circuits, even old ones in poor condition, as long as the new circuits aren't attached to them. Equipment installers set their own conditions, though, and homeowners report being asked for an electrician's letter confirming there is no live knob and tube. ### When do Eversource, National Grid or Belmont Light get involved? Only when the service changes. A rewire on the existing service stays between the contractor and the inspector of wires. A larger service needs the utility: Eversource serves Boston, Cambridge, Somerville, Brookline and Newton, National Grid serves Medford and Malden, and Belmont Light serves Belmont. The utility's process and timing then become part of the schedule. ### Does the city inspector check the work? Yes, for code compliance. Massachusetts rules say new wiring can't be covered until the inspector of wires has seen it, so there is a rough-in inspection before walls close and a final inspection when the work is done. In Boston the inspector contacts the contractor within 48 hours of the request, and the licensed contractor must be on site. The inspection covers the electrical code, not plaster patching or finish quality. ### Is commercial and mixed-use work included? Yes. Knob and tube in storefront buildings, mixed-use properties and larger apartment buildings can be arranged through this site. A building on a commercial meter may fall under Mass Save's business barrier path instead of the residential one, which caps knob and tube verification incentives at $2,000 for buildings under 8,000 square feet and requires a signed weatherization proposal. Eligibility is confirmed with the program sponsor for each building. ### What should I have ready before I call? The town and type of building, how many units it has, roughly when it was built, and what started this: an insurer's letter, a home inspection report, a Mass Save assessment or a renovation. Photos of the panel and of any wiring visible in the attic or basement help, taken without touching anything. Mention any deadline tied to a closing, a policy renewal or an insulation date. ### Will the house need new smoke and carbon monoxide alarms? It depends on the project. Whether an electrical rewiring permit triggers hardwired or interconnected smoke and carbon monoxide alarms is set by the state building and fire codes and confirmed with the local inspector for each job. Alarm work is permitted separately in some cities; Cambridge and Somerville list alarm devices on their electrical fee schedules. If alarms are needed, adding them while walls are open is far easier.