Main ServiceDisconnect

Does anyone know when the NEC first required a Service Disconnect?

230.7 General: Means shall be provided to disconnect all conductors in a building or other structure from the service entrance conductors.

(I am familiar with the rule of sixes.)

No. It goes back as far as I can remember, but why would it matter? If you are not doing code compliance inspection / enforcement, the concept of grandfathering does not apply. Wouldn’t your comments regarding the lack of a main disconnecting means be essentially the same regardless of how old the house is relative to the introduction of the requirement?

I wrote up a system without any service disconnect as a safety issue on an older house & the client asked me when it became mandatory to have a main disconnect. I told him “A Long Time Ago” but I really don’t know the precise answer. As you say, it really does not matter - just wanted to add to my knowledge base if anyone knew.

According to this a service disconnect has been required since the first NEC was published in 1897.

"In 1897, the electrical experts of the time decided “there must be a main disconnecting switch installed at every building to disconnect all service wires, either underground or overhead, and that it be located in a readily accessible place as near as possible to the point where the wires enter the building. This disconnecting means must be arranged to cut off the entire current.”

These early safety experts also felt that electrical power should be turned off when the last person left the building for the evening, so the disconnect was required to be reasonably easy to access as that person exited the building."

Thanks for the history lesson - good info.

Charles - I understand wanting to be able to respond to the inquiry, I would want to do the same.

Enjoyed the article - I guess that pretty much settles the time & date question. Thanks Chris :smile:

Damit! I really wanted to know as well.
What good it will be to me… I imagine none.
However, Thanks!

This is directly from the 1909 NEC: