From the 1920s through the 1960s, cloth-covered wires were often used in homes. When homeowners are uninformed of the fire hazards or already have insurance on the home, cloth-covered wiring is nevertheless used. Cloth, on the other hand, will have to be replaced during the home selling process.
When was Romex made of cloth?
Above the same do-it-yourself-er has left at least six, probably more unsafe details at this electrical receptacle:
- Strain relief on armored cable is missing.
- Wiring for an extension cord was employed to extend the circuit.
- Second circuit (below the armored cable) stripped back without connection to the electrical box at all
- For the quantity of conductors, the electrical box is too tiny.
- The electrical box was not properly fastened to the structure.
- The electrical box has no cover plate.
The front of this add-on electrical receptacle is seen below. One thing is “correct” though: the installer used a two-prong receptacle that excludes a third ground prong opening – as he should have done as the circuit does not include a grounding conductor.
Black, Gray, Silver & White Colored Fabric Covered NMC Electrical Wire Insulation
On cloth or fabric-insulated NMC electrical wires, the external insulation is usually black, silver, or white, although it can also be black or brown.
Individual conductors within the wire may be insulated with rubber or fabric-covered rubber, or newer wiring products may use plastic to insulate them.
See the history of fabric-insulated wire makers, as well as dates, trademarks, and identifying images of a variety of cloth-insulated wire kinds.
at FABRIC NMC WIRE INSULATION IDENTIFICATION where we also discuss Paraflex & Paranite Insulated Electrical Wiring
Knob & Tube Electrical Wiring
Separate hot and neutral wires were suspended in the air, spaced 2 1/2″ or more apart, and protected from touch with wood framing by ceramic knobs or, where wire had to pass through a wood framing member, ceramic tubes.
Both of these are depicted in the image below. By 1940, knob and tube wiring had lost favor in North America, but it was still being installed as new work in select places (including New York) until 1975.
Article 394 of the United States National Electrical Code (2005) still refers to this wire as pre-existing or “old-work” electrical wiring.
at KNOB & TUBE WIRING – topic home, where we discuss assessing the condition of knob and tube wiring and issues concerning improper extensions of knob and tube circuits.
Plastic or Nonmetallic Cable (NMC) Insulated Electrical Wiring:Romex Cable Wiring
NMC, sometimes known as “Romex,” has been in use in the United States since before 1926, according to Dini (2006).
In the 1950s, plastic NMC began to replace both rubber and fabric-based wire insulation in the United States. PVC refers to polyvinyl chloride-based plastics.
Plastic or thermoplastic nonmetallic cable, such as the one pictured below, which is still referred to as “Romex” cable by many electricians, has been in use since the 1960s and by 1970 had totally replaced fabric-based wire insulation materials in new home construction in the United States.
Local electrical codes in several jurisdictions, particularly some large cities, demand steel armored cable.
Instead of plastic NMC, use armored cable (BX WIRE IDENTIFICATION) or electrical conduit.
Rubber-Insulated Electrical Wires
It’s safe to argue that rubber, in a slightly different form, was the first electrical wire insulating material, at least in the United States, as evidenced by Edison’s 1892 patent, which includes the following excerpt from Edison’s wire insulation description:
The goal of my invention is to effectively insulate wire so that it is waterproof and can be used in moist environments and even under water without losing its insulating properties, as well as fire-proof, so that if the wire becomes red-hot by accident, the insulating-covering will not catch fire and burn, but will instead oxidize, leaving the wire pyro-insulated.
The employment of a mixture of rubber and an infusible material in the form of a powder as an insulating-covering is the invention’s key characteristic.
However, electrical power line and wiring insulation was formerly available in the form of rope, tarred fabric, and even wood. However, the rubber insulated wire depicted in Edison’s 1892 patent was the first cost-effective branch circuit conductor wire insulation method that could be mass-produced mechanically and affordably.
More electrical generator equipment from Edison’s time can be viewed at the Pratt Institute, which is still on display.
Mixed-Media wire: rubber-insulation over plastic-coated copper electrical wires
Above: This cable was a short segment of extension cord that had been plugged into a wall-mounted electrical outlet to connect a permanently-mounted fluorescent light fixture to power.
A example of plastic-insulated multi-strand electrical wire enclosed in the rubber jacket seen above is shown below.
When the light stopped working, the author discovered that the insulation on this wire had deteriorated, crumbled, and was dangerous.
These conductors were insulated by fabric-covered rubber inside the outer rubber wire jacket, as seen in our rubber and fabric wire insulation photo below.
Unless you take back more of the insulating coating, the color codes (white = neutral, black = hot) on these wires can be faded and difficult to distinguish. The hot and neutral wires are combined in an exterior rubber jacket in the wire pictured below. However, the knob and tube technique was employed in the early electrical wiring systems in the United States.
For further information on knob and tube wiring, see KNOB & TUBE WIRE IDENTIFICATION in this page.
In these older conductors, you could come across tinned-copper electrical wire. Tinned-copper electrical wiring is not to be confused with aluminum electrical wiring.
Power Cable for Electric Welder
We can see a cloth fabric behind the hard rubber shell of the welder power cable, which could be asbestos fabric for added heat protection.
Other readers who are familiar with this welder cable are encouraged to use the CONTACT link at the top or bottom of the page to provide additional information.
Solid Iron Tubing or Steel Pipe & Pitch Insulated Electrical Cables
Above: We’re looking at the cut-end of a length of original DC or continuous current distribution cabling rescued from a NYC trench.
To isolate the solid copper core from the iron pipe, it was wrapped in rope, and the space between it and the surrounding iron pipe was filled with a pitch-like substance. – M.C.
Theater Electrical Wiring
We frequently encounter unusual and perhaps dangerous installations in theaters where electrical wiring is frequently temporary. The rubber-coated wires pictured below were spotted in a New York theater and appeared to be superior to what my brother-in-law Matt, a theatrical electrician, could manufacture.
Theater fires are especially dangerous since there is often a stampede to the exits, poor illumination, and a lot of flammable objects.
The Hippodrome theater in Richmond, Virginia, which opened in 1914, caught fire in 1945 when I was two years old (so I’m not to blame). The cause of the fire was suspected to be electrical.
Article 530 – buildings or portions thereof utilized as studios using motion picture film or electronic tape more than 7/8″ in width, Article 540 – wiring for motion picture projector rooms, and others are all covered by the US NEC.
Tinned Copper Electrical Wire
In the electrical panel seen above, we can observe both vintage fabric-covered electrical conductors and newer plastic-insulated wires. The virtually black bare copper cable was a clue in locating a neutral and ground wiring failure at this structure.
The same rubber-insulated electrical wire used to demonstrate the dull silvery colored metal wire seen when tinned copper electrical wiring is placed is also used to illustrate the dull silvery colored metal wire seen where tinned copper electrical wiring is installed.
In 1950, what kind of wiring was used?
Knob-and-tube wiring was the preferred wiring style for residences until the 1950s, in many places. Knob and tube wiring was a two-wire, quick-and-easy-to-install solution. A hot wire and a neutral wire were inserted as two separate insulated conductors. Converting knob-and-tube wiring to a three-wire system is a substantial project that necessitates a complete rewiring of the property.
In 1960, what kind of wiring was used?
Aluminum building wiring is a type of electrical wiring that uses aluminum electrical conductors for residential construction or residences.
Aluminum has a higher conductivity to weight ratio than copper, hence it’s used to wire power grids, such as overhead power transmission lines and local power distribution lines, as well as some airplanes’ electrical wiring.
Since the late 1800s and early 1900s, utility firms have employed aluminum wire for electrical transmission in power networks.
Compared to copper cables, it is less expensive and lighter.
Aluminum wire is still the main material for power transmission and distribution today.
Aluminum wire was utilized for wiring complete houses in North American residential construction for a brief period between the 1960s and the mid-1970s, when copper prices were high. Electrical devices (outlets, switches, lighting, fans, and so on) were not constructed with the properties of the aluminum wire in mind at the time, and there were certain concerns with the wire’s properties, making aluminum wire installations considerably more prone to problems. To address the issues, revised production standards for both the wire and the devices were devised. Existing residences with branch circuits that employ this older aluminum wiring pose a fire threat.
In 1940, what kind of wire was used?
From roughly 1880 through the 1940s, knob and tube wiring was a common technique of electrical wiring in buildings in North America. The system is considered obsolete and can be a safety hazard, although some of the fear associated with it is undeserved.
During their examinations, InterNACHI inspectors should always mention knob and tube wiring.
- It isn’t necessarily risky. The problems of this system derive from its antiquity, poor modifications, and circumstances where the wires are encased in building insulation.
- It lacks a ground wire, therefore it can’t power three-pronged equipment.
- While it is considered obsolete, no code mandates that it be completely removed.
- Different jurisdictions handle it differently. It must be removed from all accessible sites in certain localities, while others just state that it must not be installed in new buildings.
- In any new construction, it is not permissible.
The Functions of Knob and Tube Wiring:
Insulated copper conductors travel through drill holes in wooden framing via protected porcelain insulating tubes in knob and tube wiring. They are sustained along its length by porcelain knobs that are nailed in place. Wires are shielded by flexible fabric or rubber insulation called “loom” as they enter a wiring device, such as a lamp or switch, or were dragged into a wall.
Knob and Tube Wiring’s Benefits:
- Wiring systems with knobs and tubes have a higher ampacity than wiring systems with the same gauge. The reason for this is that the hot and neutral wires are separated by 4 to 6 inches, allowing the wires to easily dissipate heat into the atmosphere.
- Because Knob and Tube wires are held away from the framing, they are less likely to be penetrated by nails than Romex wires.
- The porcelain parts have a nearly infinite lifespan.
- Knob and Tube wiring is often superior to current Romex wire in terms of original installation. Knob and Tube wiring requires more skill to install than Romex wire, and as a result, it is rarely installed by untrained people.
Knob and Tube Wiring Issues include the following:
- Knob and Tube wiring is significantly more prone to unsafe alterations than Romex and other current wiring methods. Part of the reason for this is that Knob and Tube is so old that there have been more opportunities for incorrect alterations.
- The insulation that surrounds the wiring poses a fire risk.
- Over time, it stretches and sags.
- It doesn’t have a grounding conductor. Grounding conductors help protect sensitive electronics from electrical fires and damage.
- Wiring in older systems is insulated with varnish and fiber materials that deteriorate over time.
Knob and Tube wire is less resistant to damage than current wiring insulation. Knob and tube wiring insulated with asbestos and cambric is not moisture resistant. Insulation in older systems had compounds that could oxidize copper wire. When you bend the wires, the insulation may split and peel away.
Amateurs frequently splice knob and tube wiring with modern wiring poorly. This could be owing to the simplicity with which Knob and Tube wiring can be accessible.
Insulation of Structures:
Knob and tube wiring is intended to disperse heat into the outside air, but insulation will obstruct this process. Heat will build up around Knob and Tube wires if they are insulated, posing a fire hazard. This wire arrangement must not be insulated, according to the 2008 National Electrical Code (NEC). It specifically indicates that this wiring system should not be used in hollow spaces such as walls, ceilings, or attics where the conductors are encased in loose, rolled, or foamed-in-place insulating material.
Local governments have the option of adopting the NEC’s provision or not. For example, the California Electrical Code allows insulation to come into touch with knob and tube wiring if specific circumstances are met, including but not limited to:
- The system must be certified as safe by a registered electrical contractor.
- The certification must be filed with the building department in your community.
- A warning notice must be put in accessible areas where insulation covers the wire. This sign must be in both Spanish and English in some regions.
- Non-combustible and non-conductive insulation is required.
- Normal requirements for insulation must be met.
Modifications:
When knob and tube wiring was initially introduced, toasters, tea kettles, coffee percolators, and other small household electrical appliances were the only ones available.
could not have been predicted in the late 18th century, when electricity was regarded as a transitory craze by many. Existing Knob and Tube systems are renowned for being modified to accommodate the increased amperage demands demanded by televisions, refrigerators, and a slew of other electric appliances. Many of these attempts were made by inexperienced handymen, not experienced electricians, whose work exposed the wire system to overloading.
- Many homeowners compensated for the wiring’s insufficient amperage by installing fuses with resistances that were too high for the wiring. As a result of this adjustment, fuses would not blow as frequently, and excessive amperage loads would cause heat damage to the wiring.
- Inspectors frequently find connections wrapped in masking tape or Scotch tape rather than electrical tape.
Wiring for knobs and tubes, as well as insurance:
Because of the risk of fire, several insurance companies refuse to insure homes with Knob and Tube wiring. Exceptions are occasionally given for homes where the electrical system has been certified as safe by an electrical contractor.
For those that have knob and tube wiring, here’s some advice:
- Have a skilled electrician inspect the system. Only an expert can verify that the system was properly installed and modified.
- Do not overload your home with appliances, as this can result in a fire.
- The wiring should be changed if it is brittle or broken. The importance of proper maintenance cannot be overstated.
- Kitchens, baths, laundry rooms, and outside areas should not have knob and tube wiring. To be utilized safely in these areas, wiring must be grounded.
- Rewiring a home can take weeks and cost thousands of dollars, but improper wiring can cause fires, make estate sales more difficult, and make insurers wary.
- Before determining whether or not to rewire their home, homeowners should thoroughly analyze their alternatives.
- Any insulation found around Knob and Tube wires should be carefully removed by the homeowner or an electrician.
- A cost estimate for replacing Knob and Tube wiring should be obtained by prospective house buyers. They can utilize this money to get a better deal on the house.
In conclusion, due to inappropriate modifications and the addition of building insulation, Knob and Tube wiring is likely to pose a safety concern. Inspectors should be mindful of this antiquated method and be prepared to warn their clients about the risks it poses.
Is there asbestos in all fabric wiring?
Asbestos (a silicate material) was once the main component of the insulation cloth used to protect electrical wiring. Because of the strength of the fibers and their high resistance to heat, asbestos was regarded to be suitable for this purpose at the time. In the event of an electrical short, the cloth around the wiring would prevent fires from spreading from the cables.
Asbestos, on the other hand, has been shown to be harmful to human health. In the early twentieth century, the first tests on the toxicity of asbestos were conducted. Medical research found a link between asbestos exposure and a variety of health problems, including cancers like mesothelioma, which was originally linked to asbestos in the 1940s and prompted the first legislation restricting its use.
Plerual effusion, a condition in which extra fluid accumulates around the lungs, was also caused by asbestos. Asbestos even lends its name to a disease: asbestosis, which was first diagnosed in 1924. Inhalation of asbestos fibers causes irritation and scarring.
Asbestos is no longer used to produce cloth wiring as a result of research into the harmful consequences of asbestos exposure. Non-toxic materials are used in all modern cloth wiring. Our professionals will not use asbestos in any of the electrical work they undertake for you.
Kilowatt Heating, Air Conditioning, and Electrical in Los Angeles, CA, and the surrounding areas, provides high-quality electrical wiring services.
How can you know if a wire is fabric or not?
What Are the Signs That I Have Cloth Wiring? What Should You Look For? There’s a strong probability you have cloth wiring if you have knob-and-tube wiring. Even if your wiring appears to be rubberized, it is most likely made up of rubber on the outside and insulating cloth on the inside.
What is the name of the cloth-covered wire?
That’s exactly what cloth-covered wiring is! Wires are covered in cloth. Today, we use Romex, a type of plastic/rubber. The featured image of this post shows cloth wiring. The braiding, as well as the fraying that occurs at the ends, can be used to identify it.
Cloth wiring, in the form of Knob and Tube wiring, may be seen in residences built before the 1920s.
What are the hazards?
This style of wiring has a number of flaws that can put residents’ safety at risk. The following are the details:
- The ends of cloth wiring fray. There is a risk of fire, heat exposure, and exposed wire as a result of this.
- Asbestos may be present in the textile.
- Inhaling asbestos is dangerous.
- Insulates poorly.
- The cloth’s ability to retain heat has deteriorated in recent years. The bar has been raised significantly in recent years.
- It’s possible that you’re weak in grounding.
- Today’s homes are grounded, which means that if an arc occurs, the energy flows to the “ground” rather than to a person.
With all of those issues, it’s easy to see how anything may eventually create a fire. Especially if the textile insulation is being chewed on by rodents!
Essentially, cloth wiring is obsolete and frequently maintained in an amateurish manner, making it dangerous.
Fire Hazards and Insurance
Insurance companies will not insure homes with cloth wiring due to the difficulties mentioned above. Cloth wiring will have to be updated with modern wiring standards.
Why it becomes an issue during the home buying process
In Florida, if someone wants to buy a house and get insurance, they must have a four-point inspection conducted. Because the four-point will report on cloth wiring, insurance firms will require replacement before finalizing a house insurance coverage.
You might be able to find an insurance company that will accept a policy with cloth wiring in exceptional circumstances. Expect substantially higher insurance costs, however.
Is it necessary to rewire a 1950 house?
When considering a house rewire, there are numerous factors to consider, just as there are when making any big improvement. It’s better to see an experienced, licensed electrician about all of these concerns, but here are some things to think about.
We’ve already talked about older homes, but even newer homes may require rewiring. A partial rewire may be considered if you are planning a big remodeling and wish to add huge appliances that require a dedicated circuit or lights where there was none previously. This could be the perfect time to rewire your home because the walls will most likely be open, reducing costs.
- If it was wired before 1950 and hasn’t been upgraded, it’ll almost certainly need to be rewired to replace the cloth-insulated wiring.
- If the home’s wiring is cloth-insulated.
- If the house is wired with knob and tubes. This is common in homes constructed prior to 1935.
- If the house is wired with aluminum. During the 1960s and 1970s, this sort of wiring was employed in place of copper wiring. Aluminum wire can cause a fire. However, rather than a complete rewire, the wiring can be improved to make it safe for a reduced cost.
- If the electrical system or outlets in a home are not grounded. To prevent fires and electric shock, grounding guides surplus energy out of the house.
- If your home lacks adequate power or outlets to meet your needs, an update will assist you get your home to meet your needs.
- If you find yourself utilizing numerous extension cords on a regular basis, you may require additional outlets, which may necessitate an upgrade to your electrical system.
- It is necessary to replace an electric panel if it is not safe. This could or could not be part of a home rewire.