What You Need to Know About Electrical Wiring in Early 20th Century Homes

by Greg on April 14, 2020

retro light bulb closeup

The electricity in your home may be something that you take for granted until it doesn’t work. It may come as a shock that electricity didn’t start being a normal part of homes until early 1900. Throughout this first century of home electricity, there are a lot of wiring types and hazards that homeowners of today should be looking out for.

Knob And Tube Wiring

In the very early days of wiring, knob and tube wiring was the main system utilized. It’s composed of porcelain knob insulators and rubberized cloth fabric that encases the metal wiring. This system called for neutral and hot wires to be run separately to ensure safety in the home. However, the major pitfall of this system is wiring splicing. Homeowners or even contractors in the 1900s would cut wires at random places to attach a new wire. This lacked the safety of a neutral wire and the wires became exposed over time, even with electrical tape.

Greenfield Wiring

Greenfield wiring, also known as flexible armored cable, took over as a popular installation between 1920 and 1940. This type of wiring offered a metal cable that encased the wiring to ensure its safety throughout the home. This fixed the splice problem that knob and tube presented. However, Greenfield wiring didn’t come with a ground wire. The metal flexible cable tube is to be utilized as the ground for the system. If the metal cable is not fully intact from the service entrance and ground rod to the areas throughout your home, electrical rewiring is a must.

First-Generation Sheathed Cable

This first-generation sheathed cable is somewhat similar to what is commonly utilized today. Instead of using a flexible metal enclosure, this product used a rubberized fabric sheath. This allowed for more flexibility in wiring installation. However, the drawback to this early system is that both the hot and neutral wires were both run in the same single sheathing material. In addition, there was no ground wire installed in this sheathed wiring.

Aluminum Wiring

The metal that has been used in wiring applications has changed throughout the 20th century. Traditionally, copper was utilized in early wiring applications as it’s the best conductor of electrical current. However, copper prices in the mid-1960s skyrocketed and forced manufacturers to utilize another material. Aluminum and copper-coated aluminum were widely used in many residential installations as it’s considered a safe alternative to copper. After copper prices went back into an affordable range, it’s now the predominant metal used in wiring. If you have aluminum wiring in an older home, it’s important to note that it can be an issue when utilizing a device that is meant for solely copper wiring.

Electrical wiring has changed over the years due to safety concerns and material demand. Understanding the faults of the early 20th century home wiring can help you to remedy these problems in your old home. If you’re not overly familiar with wiring, then you should always hire a professional to remedy any electrical issues in your home.

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