How Much Does Knob and Tube Wiring Replacement Cost?
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Homeowners who live in older homes may find themselves upgrading knob and tube wiring for safety and efficiency, with costs ranging from $12,000 to $36,600, or a national average of $24,300.
Highlights
- Knob and tube wiring replacement costs are higher than many other home improvement projects at $24,300 on average or between $12,000 and $36,600.
- Homeowners can expect home size, accessibility of the wiring and panels, labor fees, permits, repairs, and electrical upgrades, to influence the total cost to replace knob and tube wiring.
- Upgrading to a modern electrical system offers homeowners a safer environment, improved energy efficiency, decreased energy costs, and improved home salability.
- Electrical rewiring projects come with inherent risks during the installation and after, so homeowners are advised to hire a qualified electrician. In many cities, electrical upgrades must be completed by a licensed electrician in order to obtain necessary permits.
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According to the International Association of Certified Home Inspectors (InterNACHI), knob and tube wiring is an older electrical system that was first introduced in the late 1800s and lasted into the early 20th century. While it’s no longer used today, homeowners may come across properties that rely on a knob and tube wiring system during their home-buying process. Knob and tube wiring can be dangerous if it’s not properly maintained or if it’s overloaded, which is why many people opt to replace the system sooner than later to meet modern safety standards.
Replacing a knob and tube system can be a significant investment, with costs ranging from $12,000 to $36,600 depending on several factors, such as house size and local permit costs. The national average knob and tube wiring replacement cost is $24,300, as reported by Angi. While the price may be a higher investment than expected, the benefits can help ensure the safety of the household and reduce electricity usage and costs in the long run.
What is knob and tube wiring? Why do I need to replace it?
Knob and tube wiring is a type of early electrical system that proved relatively easy to install and played an important role in introducing electricity to homes. However, it is considered unsafe by today’s standards. “Knob and tube wires encompass ceramic ‘knobs’ and ‘tubes’ that carry electricity throughout your home,” explains Dan Mock, the vice president of operations at Mister Sparky, an electrical franchise company with locations across the U.S. “These cables might look similar to the ones used today, but they are dangerous. This is because they contain no ground wire, which increases the chances of an electrical spark. K&T (knob and tube) wires, therefore, could cause a fire in your home.”
In addition to knob and tube wiring outlets lacking grounding capabilities, the insulation in knob and tube electrical wiring can become brittle and crack, creating a fire risk. A knob and tube wiring system is also unlikely to be able to handle the electrical needs of a modern home. In some areas, it’s impossible to secure knob and tube wiring insurance for a home due to the additional risks the systems impose. For these reasons, replacing a knob and tube wiring system is considered a necessary and wise investment.
Factors in Calculating Knob and Tube Wiring Replacement Cost
There are several main factors homeowners will need to consider when calculating knob and tube wiring replacement cost. For example, larger homes will likely require more materials and labor than smaller homes, resulting in higher costs. Homeowners can also factor permits and labor fees into their budget when they are replacing knob and tube wiring.
Need knob and tube wiring replacement?
This is no DIY task. Get free, no-commitment project estimates from electricians near you.
Home Size
The cost of rewiring a house depends heavily on its size. The larger the square footage of a home, the more wiring, fixtures, switches, and outlets it is likely to require. Larger homes also tend to have more custom features, such as vaulted ceilings, elaborate lighting setups, or specialty rooms (like a media room), which may require specialized electrical work.
While having a smaller home doesn’t guarantee a low knob and tube wiring replacement cost, it often means a more straightforward and cost-effective process. Homeowners can expect to pay a new construction electrical cost per square foot of $10 to $20 to rewire their home. Using a rewiring cost calculator or reviewing average costs for each item can help homeowners determine an accurate budget.
| Home Size | Average Cost (Materials and Labor) |
| 800 square feet | $8,000 to $16,000 |
| 1,300 square feet | $13,000 to $26,000 |
| 1,600 square feet | $16,000 to $32,000 |
| 2,000 square feet | $20,000 to $40,000 |
| 2,500 square feet | $25,000 to $50,000 |
| 3,000 square feet | $30,000 to $60,000 |
Accessibility
Electrical wiring costs for a new house are often the cheapest since the walls have not been sealed up yet. However, replacing wiring in existing homes is more challenging. Since knob and tube wiring was prevalent in homes built between the 1880s and the 1940s, it’s not uncommon to come across certain structural elements, such as plaster walls or historic architecture, that make it more challenging to update the wiring.
Homes without easy access often require specialized skills and equipment to safely replace knob and tube wiring systems, significantly boosting the overall price to rewire a house. When budgeting for a replacement, homeowners can consult with a pro about how accessible their home is to account for any complications that might affect costs.
Labor
Labor costs can make up a large portion of the cost to rewire an old house. But just how much does an electrician cost? Professional electricians typically charge hourly rates of $50 to $100 for their services. Since wiring replacement projects can take weeks, electrical wiring pricing can start to add up.
Some electricians charge a flat rate per project or for each outlet, fixture, or switch being replaced. These charges can range from $100 to $350 or more, depending on the complexity of the work. To avoid costly surprises, it’s important for homeowners to clarify what is and is not included in labor costs when replacing wiring, from preparation and installation to finishing work and cleanup.
Permits and Inspections
Permits and inspections are mandatory in most areas when house wiring systems are being updated. This is to ensure the electricians will comply with current safety and building code requirements. Homeowners can expect to pay between $100 and $125 per permit on average, though pricing can range from as little as $10 to as much as $500. Not securing the necessary permits for electrical work can result in fines or legal consequences—not to mention safety hazards from the work itself.
Both pre- and post-inspections are likely to be required when homeowners are replacing knob and tube wiring. Homeowners can expect to pay between $100 and $150 per inspection. While they are an added cost, these inspections provide an additional layer of safety assurance beyond work done by a professional electrician, who will ensure the work meets the required standards.
Additional Costs and Considerations
In addition to the cost-influential factors that affect most rewiring jobs, there are a few other considerations homeowners will want to be aware of. Homeowners can avoid going over budget on knob and tube wiring upgrades by understanding how these factors affect electrical house wiring replacement costs.
Electrical Panel Upgrade
Also known as a breaker box, an electrical panel distributes electricity from the main power source to all the different areas of a home and property. When replacing knob and tube wiring, electricians will usually upgrade the electric panel to a higher amperage to accommodate increased electrical needs. This is crucial since modern homes have many more appliances and electronics that draw more power. Where knob and tube systems usually run on a 60-amp electrical box, most homes require at least 100 amps or as many as 400 amps to operate safely.
Whether the panel needs to be replaced will depend on the panel’s age, capacity, and compatibility with the new electrical system. Homeowners can expect around $1,274 as the cost to replace an electrical panel.
Need knob and tube wiring replacement?
This is no DIY task. Get free, no-commitment project estimates from electricians near you.
Repairs
After a knob and tube wiring system has been replaced, wall repairs are often required to restore a home to its previous state. While some projects may need only a few small patches, others may require full drywall replacement. Repairing the walls often comes at an additional cost beyond the price to rewire the electrical system.
The type of wall that needs repair will affect the cost of drywall repairs. Most modern homes are built with drywall, but older homes may use a lath and plaster combination, both of which have their own repair price. For example, drywall repairs average $50 to $150 per square foot, with a total average cost range of $60 to $900. Repairing lath and plaster walls will run $80 to $200 per square foot.
Cleanup and Disposal
Post-project cleanup typically involves removing debris, dust, and any discarded materials. The cost of cleanup and disposal could be between $300 and $500, depending on whether the electrician can haul away the garbage or if a dumpster rental is required for drywall debris.
Homeowners may want to hire one of the best cleaning services (like The Maids or Merry Maids) if they prefer not to clean the drywall dust or other debris themselves. Depending on the home’s size and cleaning scope, house cleaning costs range from $30 to $250 per hour.
Electrical Upgrades
Replacing knob and tube wiring often involves upgrading outlets, switches, and lighting fixtures to accommodate the electrical demands of modern appliances and electronics. It’s also the perfect time to add any convenience upgrades, such as 3-way switch wiring or additional light fixtures. Current codes require that rooms have a sufficient number of outlets placed every 12 feet at minimum, according to the National Electrical Code (NEC).
Homeowners will want to budget accordingly to ensure that their home complies with local codes and can safely accommodate appliances such as larger refrigerators, TVs, and washers and dryers. Many outlets installed in bathrooms, kitchens, and laundry rooms are GFCI (ground fault circuit interrupter)-compliant, meaning the outlet automatically cuts power to help prevent sparking or current overload if a power surge is detected. The average installation cost of a GFCI outlet, including materials and labor, is $130 to $300.
| Type of Electrical Upgrade | Average Cost (Materials Only) |
| Ceiling fan | $150 to $360 each |
| Existing light switch replacement | $50 to $150 each |
| Existing outlet replacement | $125 to $250 each |
| GFCI grounded outlet | $10 to $25 each |
| Light fixture | $160 to $950 each |
| Light switch | $100 to $200 each |
| New electrical outlet | $140 to $300 each |
| Smart outlet | $25 to $50 each |
Benefits of Choosing Knob and Tube Wiring Replacement
In most scenarios, knob and tube replacement is necessary to bring a home up to code. But this doesn’t mean there aren’t additional benefits for the home’s occupants to enjoy. Homeowners can rest assured that there’s more safety and improved efficiency for starters.
Need knob and tube wiring replacement?
This is no DIY task. Get free, no-commitment project estimates from electricians near you.
Improved Safety
Upgrading home electrical wiring to a more modern system offers improved safety over a knob and tube wiring system for several reasons. Knob and tube wiring lacks adequate insulation, which can break down due to the higher continuous circuit of electricity running through it to power more appliances. These systems are also not designed to handle the electrical demands of modern homes and risk overheating. “With K&T there are no options to enable installation of modern safety protection devices such as GFCI (ground fault) or AFCI (arc fault),” adds Mock. “If you have K&T wires in your house, don’t panic. Hiring an electrician to upgrade these cables is simple and effective, and it might be less expensive than you think.”
Improved Efficiency
Old electrical wiring can lead to energy waste and higher utility bills. Modern systems are designed to work better w