Types of Electrical Conduit in History

Electrical conduit routes wiring through buildings and provides them with protection.

Electricity powers many devices in modern homes, typically with wiring that runs through electrical conduit. Types of conduit have developed to suit construction requirements and codes.

Early Conduit

Starting in the 1860s, conduit known as Orangeburg pipe consisted of cellulose fibers bound together with water-resistant glue, and then sealed using coal tar pitch. In modern times, electrical conduit more commonly contains materials such as PVC, aluminum and steel.

Gas to Electricity

In the early 20th century, as people converted gas light fixtures to electricity, they usually ran the wires through existing gas pipe. This served as a simple way to route wiring through walls and ceilings, and also afforded it some protection. As electricity became a more common power source, conduit developed specifically for the purpose of routing and protecting electrical wiring.

Codes of Practice

Local and national codes of practice specify the requirements for electrical conduit. NFPA 70: National Electrical Code, produced by the National Fire Protection Association, serves as a national standard that dates back to the 1890s. It provides guidance on acceptable practices for the installation of wiring in buildings, including details on electrical conduit types used over the years.

References

• Sewer History: Orangeburg
• Allied Tube: Conduit
• World Lingo: Electrical Conduit
• National Fire Protection Association: History

Resources

• NFPA: NFPA 70: National Electric Code