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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Here’s links to a collection of our other blog posts about ELECTRICAL WIRING:

What is the electrical "service point" of a house?

Which house appliances need a dedicated electrical circuit?

Can a short circuit cause a high electric bill?

What is the maximum spacing requirement for securing NM-cable (nonmetallic-sheathed cable)?

Is it alright to just put wire nuts on the end of unused or abandoned NM-cable or wiring?

What causes copper wires to turn green or black in an electric panel?  

What are typical aluminum service entrance wire/cable sizes for the electrical service to a house?

Why is it unsafe to bond neutral and ground wiring at subpanels?

Should I get a lightning rod system to protect my house?

Why is a strain relief clamp necessary for the cord connection to some electric appliances?  

Does a wire nut connection need to be wrapped with electrical tape?

What is the minimum clearance of overhead electric service drop wires above a house roof?

What are the requirements for NM-cables entering an electric panel box?

What is the color code for NM cable (Romex®) sheathing?

Why is undersize electric wiring in a house dangerous? 

What causes flickering or blinking lights in a house?

Why are old electrical components not always "grandfathered" as acceptable by home inspectors?

How can I find out the size of the electric service to a house?

Can old electrical wiring go bad inside a wall? 

What is an open electrical splice?

What are the most common electrical defects found in a home inspection? 

What is the life expectancy of electrical wiring in a house? 

What is an "open junction box"? 

How dangerous is old electrical wiring? 

What is a ground wire? 

I heard that aluminum wiring is bad. How do you check for aluminum wiring?  

    Visit our ELECTRICAL page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

Illustrations by Code Check.




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