Thanks to the Sponsors of Mass Save®, rebates and incentives for home energy-efficiency upgrades are widely available to Massachusetts residents in 2025. The program covers up to 100% of the cost of recommended insulation and air sealing, making it easy to upgrade your home comfort and bring down your monthly energy bill.
But one lurking safety hazard may be keeping you from the comfy, energy-efficient home you desire: Knob and Tube Wiring.
What is knob and tube wiring?
Dating back to the 19th century, knob and tube (K&T) wiring is named for its key components. Wires were supported by porcelain knobs attached to the sides of framing members. They were then routed through protective porcelain tubes when they would need to pass through a joist.
While K&T wiring was most popular in the U.S. between 1880 and 1910, it remained prominent into the 1950s, with some modifications:
- In the 1930s, the hot and neutral wires were run together in one “rubberized fabric coating sheath.” This sped up the installation process but still lacked ground wire.
- From the mid-1940s to the early 50s, the grounding wire was added along with a metal conduit and a plastic-coated inner wire.
Knob and tube wiring installation is prohibited for any new residential or commercial construction projects. In fact, many insurance companies will deny coverage to homes with live K&T wiring because of the increasingly high risks.
Why is knob and tube wiring dangerous?
- It lacks a grounding wire. Grounding wires were introduced around the 1950s to provide another path for electrical currents to flow into the ground. This significantly lowered the risks of electrical shocks and fires. If you have two-prong outlets instead of three-prong, that’s a good indicator that your home lacks grounding wires and surge protection, posing potential damage to your appliances and a fire hazard.
- Old materials disintegrate, leaving wires exposed. Over time, the insulation found within knob and tube wiring deteriorates, leaving behind exposed wires that are prone to causing electrical shocks, short circuits, and fires.
- Modified K&T wiring can pose its own risks. Because knob and tube wiring dates back so far, it is common to find wiring that has been adjusted in an attempt to bring it up to date. Unfortunately, modifications commonly signify incorrect and unsafe electrical work.
- It was designed for a simpler time. Our modern energy needs dwarf those of the early 1900s. Knob and tube installations can easily become overloaded by the demands of residents 100 years later. Overloaded circuits overheat and can cause house fires.
- Installing proper insulation creates an even greater fire hazard. Your home needs good insulation to prevent drafts and wasted energy, but it is impossible to install quality insulation with knob and tube wiring in place. Modern insulation traps the heat produced by the K&T wires, which builds up and ultimately combusts.
How do I find out if I have knob and tube wiring?
Schedule a Mass Save no-cost Home Energy Assessment. Not only will a HomeWorks Energy Specialist explain your home’s energy use and teach you how to start saving, they’ll also perform a health and safety check and teach you about your home. If you have knob and tube wiring in place, a no-cost Home Energy Assessment is a great way to find out now.
Most U.S. homes are under-insulated, so it’s likely that your Home Energy Specialist will recommend bolstering your home’s barrier against the elements with better insulation and air sealing. Mass Save offers great benefits to assist or even fully cover the cost of these weatherization measures. But in order to qualify for these incentives, knob and tube wiring must be removed first.
Or maybe you’d like to upgrade your heating and cooling system by installing heat pumps. In order to begin the installation process, proper insulation would be required first. Once again, knob and tube wiring stands in your way.
How do I update my home’s old electrical work?
So, what do you do if outdated knob and tube wiring is compromising your family’s safety and keeping you from a comfortable, energy-efficient home? According to Mass Save:
If your Energy Specialist recommended insulation and/or air sealing improvements during your Home Energy Assessment, but knob and tube wiring or vermiculite prevents the installation of the work, you may be eligible for an incentive to help remediate those barriers if you meet the annual household income requirements. A maximum of up to $7,000 of eligible costs will be available before the abatement work begins.
Updating an older home can feel overwhelming, but the good news is, a no-cost Home Energy Assessment will kick-start the process, and we’ll take it from there. From the moment a HomeWorks Home Energy Specialist walks through your door, you’ll be on the journey to a safe, energy-efficient, and comfortable home. We’ll make safety and efficiency recommendations, let you know what Mass Save incentives you qualify for, help you prioritize your home upgrades, and schedule the work.
Make sure your home is as safe, efficient, and comfortable as possible. You can schedule a no-cost Home Energy Assessment at no cost here – it only takes a few minutes!
More About HomeWorks Energy, Your Local Mass Save Contractor
Since 2008, our HomeWorks Energy Specialists have performed over 200,000 energy assessments and completed over 71,000 insulation jobs. The Mass Save Home Energy Assessments we provide are no cost to you and come with many benefits for homeowners and renters alike, which is why we want every Massachusetts resident to know about them! We also employ a highly skilled team of licensed HVAC and weatherization professionals, so we can see your project through from assessment to completed upgrade. Find out why we’re proud to be the largest Home Performance Contractor in the state by scheduling a Home Energy Assessment or Heating and Cooling Consultation today.
We’re your trusted neighborhood energy specialists, and we’re working to make our state greener, one home at a time.
