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user_3gw8jz
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Thursday, December 11th, 2025 7:23 PM

cable clearances from structures

I am an architect designing dwelling units on a lot in Seattle. The Comcast internet cable is right on the rear property line at the alley. What horizontal clearance is required between the cable and a proposed building?

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XfinityThomasA

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4 months ago

 

user_3gw8jz - Thank you for joining the Xfinity Forum Community. Great question, thank you for asking. 

Over roads, streets, alleys; nonresidential driveways; parking lots and other areas subject to traffic = 18 feet clearance.

Over residential driveways
a) Subject to traffic = 15.5 feet clearance.
b) Residential driveways not subject to truck traffic or where attachment to the structure does not permit service drops to meet (a) above = 11.5 feet.
 
Above sidewalks or other pedestrian traffic areas = 10 feet clearance.
 
Above Roofs
a) Above roofs not accessible to pedestrians = 3 feet clearance.
b) All points above a flat roof = 10.5 feet clearance.

Please let me know if this info was helpful.

 

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user_3gw8jz

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You have provided a detailed answer for vertical clearances but I am asking for the minimum horizontal clearance between a fiber optic cable and a proposed building.

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4 months ago

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XfinityDilary

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I did some research and found the following: 

 

When it comes to aerial fiber-optic cables near buildings, the National Electrical Safety Code (NESC) generally sets the standard in North America. While there isn’t a blanket “horizontal clearance for all fiber-to-building” installations, here are key references:

  • Window/door clearance: NESC Rule 234C3d(2) specifies a minimum horizontal separation of 3 feet from windows or other openings in buildings to prevent hazards. [ojua.org]
  • Pedestrian areas & structures: In non-power class zones, communications cables (including fiber) in communication space typically require 30 inches (2.5 feet) clearance from neutral or other conductors, which can be interpreted similarly for separation from structures in shared-use poles. [northcentr...ectric.com], [ojua.org]  

 

Note: Specific installations, such as joint-use poles or local utility poles, may have additional rules under local regulations or utility agreements. Always confirm with the latest edition of the NESC and any applicable local utility standards. 
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