What is the minimum overhead electric service drop height/clearance to a house?
Saturday, December 22, 2018
The National Electrical Code (NEC) has multiple different minimum standards, all of which depend on what is under the wires as they run from the utility pole to the service mast on your house. Thanks to Code Check, we have an excellent graphic to make things clear. Their long-time illustrator, Paddy Morrissey, loves to sneak images of Ben Franklin and his famous kite-in-a-thunderstorm experiment into their electrical diagrams, as you will notice.
Starting with the most common ones:
- Over residential property and driveways on the property (E) - 12 feet
- Over walking surfaces that are only accessible to pedestrians (D) - 10 feet
- Over a roadway (F) - 18 feet
- Over a roof low-slope roof, with less than 4/12 slope (A) - 8 feet
- Over a roof with 4/12 slope or more (B) - 3 feet
- Over a roof with 4/12 slope or more, within 4 feet of roof edge at eaves (C) - 18 inches
- Above decks and balconies, including out 3 feet (G,H) - 10 feet
- To the sides and below an openable window (I) - 3 feet
We recently got an education in the difference between the 12-foot and 10-foot clearance requirements for residential property from Jerry Peck, a retired building inspector and code consultant. The overhead service drop shown below, to a 1940s bungalow in Gainesville, was over parking spaces that had been added because the house had become a student rental, and had a 10-foot clearance at its lowest point.
We were not sure whether a parking space would qualify as a driveway for a 12-foot clearance or not. Jerry quoted NEC to make the point that ALL residential property, except areas that are ONLY accessible to pedestrians (which usually means behind a fence or other vehicular obstacle), must comply with the 12-foot rule. Even before the parking was added, it was not in compliance.
The local electric utility may have different standards, which would override the NEC code. For the clearance requirements over a swimming pool, see our blog post What are the clearance requirements for an overhead electric service drop that is directly over or near a swimming pool? And for a more detailed exploration of the requirements as the service wires cross above a roof, see our blog post What is the minimum clearance of overhead electric service drop wires above a house roof?
And by the way, if anyone is paying attention, the service mast shown at the top of the page is a 4-wire for three-phase service, which is possible, but rarely seen in residential construction. Also, it’s not necessary look up any code standards to know that the service drop shown below is wrong.
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