The Evolution of Safety in Wiring Device Design

While Thomas Edison certainly recognized the inherent danger electrical 
current could pose, the safety of the wiring devices he and his 
competitors created, back in electricity’s early days, left a great deal
 to be desired. And, with their initial focus solely on lighting, these 
developers didn’t realize the speed with which electricity would 
transform all aspects of modern life. As a result, residential and 
commercial electrical systems of the early 20th Century were often 
cobbled-together rats’ nests of exposed wiring and improvised 
connections. Hubbell Wiring Device-Kellems

Chuck Ross

While Thomas Edison certainly recognized the inherent danger electrical current could pose, the safety of the wiring devices he and his competitors created, back in electricity’s early days, left a great deal to be desired. And, with their initial focus solely on lighting, these developers didn’t realize the speed with which electricity would transform all aspects of modern life. As a result, residential and commercial electrical systems of the early 20th Century were often cobbled-together rats’ nests of exposed wiring and improvised connections.

In fact, electrical receptacles and wall switches as we now know them weren’t even a part of the earliest installations. As late as the 1920s, electrical wiring generally followed the model established by the interior gas-lighting systems they were designed to replace. Cloth-insulated conductors ran directly to the wall and ceiling fixtures they served, sometimes using the original gas piping as conduit. Chandeliers and pendants were hung by their wiring and keyed at the fixture for on/off operation. The small appliances, such as irons and electric cooking equipment, that quickly came to market as electricity’s potential was realized didn’t plug into a receptacle – instead, their wiring terminated with screw caps similar to those used with Edison-style light bulbs. Of course, this meant you had to unscrew a fixture’s light bulb and use your iron or griddle in the dark.

Safety, obviously, was almost an afterthought in these approaches, in which multiple, proprietary connector designs also proliferated. Ground-fault-related electrical shocks and arc-fault-related fires must have been frequent occurrences in homes and businesses at the time. The decades since then have seen enormous strides forward in both hazard reduction and performance improvement, driven in large part by more than a century’s-worth of updates to the National Electrical Code, first published in 1897. With arc- and ground-fault protection now required for branch circuits in almost all locations, and tamper resistance a frequent feature, today’s wiring devices offer a level of safety Edison might never have imagined.


Photo courtesy of Hubbell Wiring Device-Kellems