If your home in Aiken, SC was built before the 1950s, there is a reasonable chance it still has some knob and tube wiring behind the walls. This early electrical wiring method was the standard for residential construction from the 1880s through the 1940s, and while it was perfectly acceptable for the electrical demands of that era, it presents real concerns for modern homeowners.
Understanding what knob and tube wiring is, why it can be dangerous, how it affects your insurance, and what your options are for dealing with it will help you make informed decisions about your home's electrical system.
What Is Knob and Tube Wiring?
Knob and tube wiring, often abbreviated as K&T, is one of the earliest standardized methods of electrical wiring used in residential construction in the United States. It consists of individual copper conductors run through the framing of a house, supported by porcelain knobs that are nailed or screwed to the structural members, and protected by porcelain tubes where the wires pass through joists and studs.
Unlike modern wiring, which bundles a hot wire, a neutral wire, and a ground wire together inside a single protective sheath (called Romex or NM cable), knob and tube wiring runs the hot and neutral wires separately, spaced several inches apart. The wires are insulated with a rubberized cloth fabric, and the air space between the wires and around them provides the primary means of heat dissipation.
This system was well-engineered for its time. The porcelain insulators are extremely durable and can last well over a century. The air-gap design allowed heat to dissipate effectively, and when the system was not overloaded, it could function safely for decades. Many homes with original knob and tube wiring still have sections that are technically operational today.
A Brief History of Knob and Tube in Aiken
Knob and tube wiring was the standard wiring method in the United States from roughly 1880 to the 1940s. During this period, Aiken was growing steadily as both a local community and a destination for wealthy winter visitors who built substantial homes in and around the city. Many of the historic homes in Aiken's downtown and surrounding neighborhoods were originally wired with knob and tube systems.
By the late 1930s and into the 1940s, newer wiring methods began to replace K&T. Armored cable (BX) and early versions of non-metallic sheathed cable started appearing in new construction. By the 1950s, knob and tube was largely phased out of new homes, though it was never officially banned. The NEC eventually stopped including installation standards for new K&T wiring, effectively making it a legacy system.
In Aiken, homes built before 1950 in neighborhoods throughout the city, along Whiskey Road, in the historic district, and in older communities like Graniteville may still contain original knob and tube wiring. Some homes have had partial rewiring over the decades, leaving a mix of old K&T and newer wiring systems coexisting behind the same walls.
Why Knob and Tube Wiring Is a Concern
There are several specific reasons why knob and tube wiring raises safety concerns in modern homes. Understanding each one helps explain why electricians, insurance companies, and home inspectors pay close attention to this wiring method.
No ground wire. Knob and tube wiring has only two conductors: hot and neutral. There is no ground wire. Modern electrical systems use a ground wire as a safety path that directs stray electrical current safely to the earth in the event of a fault. Without a ground wire, appliances and devices connected to K&T circuits have less protection against electrical shock. Three-prong outlets cannot be properly installed on ungrounded circuits, and two-prong outlets limit what devices you can safely plug in.
Insulation contact danger. This is one of the most critical safety concerns with knob and tube wiring. The system was designed to dissipate heat through open air space around the wires. When blown-in insulation, fiberglass batts, or spray foam insulation is installed in walls and attics where K&T wiring runs, the insulation traps heat around the wires. This trapped heat can degrade the wire's already-aging cloth insulation and, in extreme cases, raise temperatures high enough to ignite surrounding materials.
Many older Aiken homes have had insulation added over the years to improve energy efficiency without anyone checking whether knob and tube wiring was present in those cavities. This well-intentioned upgrade can create a serious fire hazard if the insulation is in direct contact with active K&T conductors.
Deteriorating insulation on the wires. The rubberized cloth insulation used on knob and tube conductors was not designed to last 80 to 140 years. Over time, this insulation becomes brittle, cracks, and falls away from the copper conductor. Exposed copper wire inside wall and ceiling cavities creates a risk of short circuits, arcing, and fire. The deterioration is accelerated by heat, vibration, and the simple passage of time.
Overloaded circuits. Knob and tube wiring was designed for the electrical demands of the early twentieth century: a few light fixtures, perhaps a radio, and maybe an iron or a toaster. The typical K&T circuit was designed to carry 15 amps. Modern households routinely draw far more power from each circuit, with computers, televisions, air conditioners, microwaves, and dozens of other devices that simply did not exist when the wiring was installed. Overloading K&T circuits accelerates heat buildup and increases the risk of failure.
Amateur modifications. Over the decades, many K&T systems have been modified by homeowners or unqualified workers who spliced modern wiring into the old system using improper connections. These modifications can create points of high resistance, overheating, and potential fire hazard. Splice points hidden inside walls are particularly dangerous because they cannot be easily inspected.
Insurance Issues with Knob and Tube Wiring
One of the most immediate practical concerns for Aiken homeowners with knob and tube wiring is insurance. Many homeowners insurance companies in South Carolina have policies regarding K&T wiring that can significantly affect your coverage and premiums.
Some insurance companies will not write new policies for homes with active knob and tube wiring. If you are purchasing a home with K&T wiring, you may find that your preferred insurance company declines coverage, forcing you to seek specialty insurers that charge substantially higher premiums.
Other companies will insure homes with K&T wiring but require a professional electrical inspection first. The inspection report must confirm that the wiring is in acceptable condition and not covered by insulation. Some insurers will require that K&T wiring be replaced within a specified timeframe as a condition of continued coverage.
Even if your current insurer continues to cover your home, having knob and tube wiring can result in higher premiums. The increased fire risk associated with aging K&T systems translates directly into higher risk for the insurer, and that cost is passed on to the homeowner.
If you are selling a home with knob and tube wiring, be prepared for this issue to come up during the buyer's home inspection. Many buyers will request that the wiring be replaced as a condition of the sale, or they will negotiate a price reduction to account for the cost of replacement.
How to Identify Knob and Tube Wiring in Your Home
If your Aiken home was built before 1950, it is worth checking for knob and tube wiring. Here are the most accessible places to look:
The attic. If you have an unfinished attic with exposed framing, look for white or brown porcelain knobs attached to the joists and rafters, with single insulated wires running between them. The wires will be individually run, not bundled together like modern Romex cable.
The basement or crawl space. Look along the floor joists for the same porcelain knobs and individual wires. You may also see porcelain tubes where wires pass through the joists.
Outlets. If your home has only two-prong outlets with no ground slot, it is a strong indicator of ungrounded wiring, which may be knob and tube. However, some homes have had three-prong outlets installed on ungrounded circuits, which is a code violation but still occurs.
Do not open walls to investigate. If you cannot see evidence of K&T in accessible areas, do not cut into walls to look for it. A licensed electrician can use non-invasive methods and their knowledge of construction history to determine what type of wiring is behind your walls.
Replacement Options and What to Expect
If your home has active knob and tube wiring, the recommended course of action is a complete rewire of the affected circuits with modern NM cable that includes a ground wire. Here is what the process typically involves:
Inspection and assessment. A licensed electrician will inspect the full extent of the K&T wiring, determine which circuits are active, identify any hazardous conditions, and provide a scope of work for the replacement. This assessment also identifies whether your electrical panel needs to be upgraded to handle the rewired circuits.
Selective vs. complete rewiring. In some cases, only portions of the home still have active K&T wiring. Previous owners may have rewired certain rooms or circuits. Your electrician will determine whether a selective rewire (replacing only the remaining K&T circuits) or a complete whole-house rewire is the better approach. A complete rewire is generally recommended if more than half of the home's circuits are still K&T.
The rewiring process. Rewiring an occupied home requires careful planning to minimize disruption. The electrician will run new wiring through the walls, ceilings, and floors, using the existing framing cavities where possible. Some drywall or plaster may need to be opened and patched. In homes with accessible attics and basements, much of the wiring can be run without opening finished surfaces. The old K&T wiring is typically abandoned in place (de-energized and left in the walls) rather than physically removed, as removing it can cause unnecessary damage to the plaster and framing.
Cost considerations. The cost of rewiring a home varies significantly based on the size of the home, the accessibility of the wiring routes, and the extent of the work required. For a typical older home in Aiken, a complete rewire including a panel upgrade can range from several thousand dollars for a small home with good access to substantially more for a larger home where extensive wall opening and patching is required. While this is a significant investment, it eliminates the safety hazards, resolves insurance issues, brings the home up to modern code, and adds value to the property.
Can You Just Leave It?
Some homeowners wonder whether they can simply leave knob and tube wiring in place if it appears to be working fine. While K&T wiring is not inherently illegal, leaving it in place carries ongoing risks.
The aging insulation will continue to deteriorate. Any future insulation improvements in the attic or walls could create contact hazards. The lack of grounding limits what appliances and devices can be safely used. Insurance problems may worsen over time. And if you ever sell the home, the wiring will almost certainly need to be addressed.
The safest long-term approach is to replace the wiring on a planned timeline rather than waiting for a problem to develop.
Next Steps
Unity Power & Light provides comprehensive knob and tube wiring inspections and replacement services for homeowners in Aiken, SC and the surrounding CSRA area. If you suspect your home has knob and tube wiring, or if a home inspector or insurance company has flagged it, we can give you a clear assessment of the wiring's condition and a straightforward plan for replacement.
Every rewiring project we complete meets current NEC code, passes inspection, and is backed by our commitment to doing the work right. We work carefully in occupied homes to minimize disruption to your daily life while making your home's electrical system safe and modern.