ELECTRICAL WIRES HEIGHT REQUIREMENTS

[kbrinman]

I would like to find out what the NEC says about the proper heights of electrical wires above public street, roads, sidewalks, etc. Are there different requirements for different areas?

[bphgravity]

See Article 230.24 of the 2002 NEC for serviceclearance requirements.

You may also need to refer to the National Electrical Safety Code depending on the type of wiring your are concerned with.

You will have to check with your local building department to learn if there are local admendments or changes to the NEC specifications.

[pierre]

Also refer to 225.18 for outside branch circuits and feeders

Pierre

[bennie]

NESC Section 23, clearance over roadway is 15 feet. NEC the clearance is 16 feet.

The cable is in the jurisdiction of the NESC, 15 feet will be the standard.

[websparky]

kbrinman,

The answer to the question you asked;

NEC 2002 230.24 Clearances. (B) Vertical Clearance from 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.

Hope this helps,
Dave

[ July 11, 2003, 06:58 PM: Message edited by: websparky ]

[bennie]

websparky: You are correct I misread the dimension. The Local inspector enforcing the NEC dimension will have a hard way to go.

A service drop should not be in the NEC.

The dimension established by the NESC is an engineered calculation based on height of standard power poles. 18 feet may be possible at the feed point, but 15 feet is more likely at the sag point.

Remember the power company will not install any line higher than necessary.

On the same subject...I hold the record for installing the worlds highest above ground power line. The line was 10,000 feet above the earth, on two by four poles.

[luke warmwater]

Bennie, wasn't that 'above Sea Level'?

[bennie]

No, the power line was 10,000 feet above the dirt. The dirt was at sea level.

[peaveyone]

Hi all, I was recently travelling to Columbus and happened to see transmission towers in the Megavolt range not sure of the exact voltage. Point is at the sag between these towers they couldnt have been more than 20' from the ground! I actually stopped and surveyed the surroundings. Over the road If two or three semis went under them at once they would move. Out over the corn field the lines werent even as high as the aprox 20 acres of trees that ran adjacent to them. These arent red woods either they are you typical NW Ohio deciduous timbers. Every drop of the 3phases were in arrays of 4 cables with square seperators keeping the 4 wires from tangling. Arent these lines actually supposed to be at a hieght greater than that of standard secondary transmission lines? I just worry that some unsuspecting farmer will snag this some day when he is shooting across the field with his cultivator extensions raised.

Hey Bennie, 10,000' I hope it payed good.

[bennie]

Peaveyone: The line is 230 KV or more. Conductor bundling is done to to reduce the energy field, decrease resistance, and reduce the inductive reactance. The conductors are shorted together at each spacer.

Line sagging is an engineered design, for tension and weight of the span. The integrity of the entire string depends on accurate sagging.

A farmer will not make a habit of hitting the lines.