Thread: Service Drop Clearance Over a Pergola?

Alright all you electrical hot-shots, here's a clearance question for you. This service drop comes in overhead over a pergola that's built up over a patio. It's over the 10 ft. min. from ground/patio level, but it's only 4-6 inches over the top of the pergola. My Code Check Complete doesn't cover this situation. It's not like a low pitched roof where people are likely to walk on it from time to time - but it is possible that people could walk on it as long as they watch where their feet are landing. Do we have a clearance problem here? What is your opinion on this one? Thanks a lot for your help with this!

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NEC 230.9(B) would require 3' of clearence. IIRC a power company near me requires 11' under the triplex over the roof.

Look at it this way. They are able to walk up to, step over, grab a hold of, swing, or whatever to the service entry cables, even if the structure wasn't there.

Originally Posted by Wayne Carlisle

Look at it this way. They are able to walk up to, step over, grab a hold of, swing, or whatever to the service entry cables, even if the structure wasn't there.

How does this fit into the condition as posted by the OP?

Originally Posted by Michael Chambers

Alright all you electrical hot-shots, here's a clearance question for you. This service drop comes in overhead over a pergola that's built up over a patio. It's over the 10 ft. min. from ground/patio level, but it's only 4-6 inches over the top of the pergola.

He's worried about someone being able to walk on the Pergola and being able to grab hold of the cables....take the Pergola away and you still have that condition with someone able to grab the cables if they are on the roof.

Originally Posted by Wayne Carlisle

take the Pergola away and you still have that condition with someone able to grab the cables if they are on the roof.

There is an allowance for cables to be over the roof, regardless of the pergola.

To avoid the situation above you would need to install the cables out of reach from someone on the roof. Is someone saying the cables now need to be 10' over the roof so that someone cannot reach them?

Originally Posted by Jim Port

NEC 230.9(B) would require 3' of clearence. IIRC a power company near me requires 11' under the triplex over the roof.

You mean 230.24(A) and 8 feet, right?

Point for debate, is the pergola a roof?

230.24(A) also has an exception 3 that allows for the reduced clearence of the original installation. I know that this exception would not apply to the pergola.

From further reading 230.24 is probably a better Article than 230.9.

- 230.24 Clearances.
- - Service-drop conductors shall not be readily accessible and shall comply with 230.24(A) through (D) for services not over 600 volts, nominal.
- - - (A) Above Roofs. Conductors shall have a vertical clearance of not less than 2.5 m (8 ft) above the roof surface. The vertical clearance above the roof level shall be maintained for a distance of not less than 900 mm (3 ft) in all directions from the edge of the roof.
- - - - Exception No. 1: The area above a roof surface subject to pedestrian or vehicular traffic shall have a vertical clearance from the roof surface in accordance with the clearance requirements of 230.24(B).
- - - - Exception No. 2: Where the voltage between conductors does not exceed 300 and the roof has a slope of 100 mm in 300 mm (4 in. in 12 in.) or greater, a reduction in clearance to 900 mm (3 ft) shall be permitted.
- - - - Exception No. 3: Where the voltage between conductors does not exceed 300, a reduction in clearance above only the overhanging portion of the roof to not less than 450 mm (18 in.) shall be permitted if (1) not more than 1.8 m (6 ft) of service-drop conductors, 1.2 m (4 ft) horizontally, pass above the roof overhang, and (2) they are terminated at a through-the-roof raceway or approved support.
- - - - - FPN: See 230.28 for mast supports.
- - - - Exception No. 4: The requirement for maintaining the vertical clearance 900 mm (3 ft) from the edge of the roof shall not apply to the final conductor span where the service drop is attached to the side of a building.
- - - (B) Vertical Clearance for Service-Drop Conductors. Service-drop conductors, where not in excess of 600 volts, nominal, shall have the following minimum clearance from final grade:
- - - - (1) 3.0 m (10 ft) — at the electrical service entrance to buildings, also at the lowest point of the drip loop of the building electrical entrance, and above areas or sidewalks accessible only to pedestrians, measured from final grade or other accessible surface only for service-drop cables supported on and cabled together with a grounded bare messenger where the voltage does not exceed 150 volts to ground
- - - - (2) 3.7 m (12 ft) — over residential property and driveways, and those commercial areas not subject to truck traffic where the voltage does not exceed 300 volts to ground
- - - - (3) 4.5 m (15 ft) — for those areas listed in the 3.7-m (12-ft) classification where the voltage exceeds 300 volts to ground
- - - - (4) 5.5 m (18 ft) — over public streets, alleys, roads, parking areas subject to truck traffic, driveways on other than residential property, and other land such as cultivated, grazing, forest, and orchard

230.24(A) establishes a minimum height of 8 feet, with exceptions as follows:
- Exception 1, which takes us to 230.24(B) with 10 feet, 12 feet, 15 feet, and 18 feet options based on the conditions applicable to each, thus Exception 1 is not applicable here..
- Exception 2, which allows 3 feet if the roof has a slope of 4/12 or greater, and that roof is not slope greater than 4/12, thus Exception 2 is not applicable here.
- Exception 3, which allows 18 inches for the portion of the conductors which are only over the overhang, thus Exception 3 is not applicable here.
- Exception 4, which allows the 3 feet vertically above the edge of the roof to not apply, and this only applies to the final conductor span to where it is attached to the building, thus Exception 4 does not apply here.

"Point for debate, is the pergola a roof?"

If not a roof, what is it?

At a minimum, the height above the ground/deck/surface below would need to be at least 12 feet, but should also be kept 3 feet from the edges of that roof, and if over that roof then 8 feet high above it.