Code Question: Service Wire Over Garage

[DerbyDad03]

First Question:

Is there a spec for the minimum distance between the service wire to a house and a garage roof?

I dropped my son off to help a friend roof a garage that the friend had just rebuilt. Before I left I climbed up on the roof to say Hi and saw that the service wire to his neighbor's house ran from a pole in my friend's back yard, diagonally over his garage, dipping to within 3 feet of the roof. It then arched upwards to the neighbor's house. They had to basically crawl under the service wire to roof that side of the garage.

I asked him (the friend) if that was legal and he said that he had gotten a permit from the town to rebuild the garage, so he assumed it was. In fact, he had originally planned to make the garage a few feet taller but didn't because of the service wire.

Second Question:

Would it be dangerous to touch that service wire while standing on the garage roof?

My friend was adamant that no one and no thing touch the wire. While I completely support his notion that it's a probably a good idea *not* to touch the wire, is there really a danger of being electrocuted by touching the service wire while standing on a garage roof?

[gfretwell]

The rule is 8 feet and yes it will kill you if you manage to touch an ungrounded conductor. The insulation on modern triplex drops should protect you but stuff still happens. I am not sure how an inspector passed this if he actually looked up.

[RBM]

It does seem strange that someone elses service drop would be that close to his garage. I would think an easement would have to have been granted.

For a residential drop, it can be as close as 3 feet to the roof provided that the roof pitch is at least 4" in 12".

Typical steel core messenger cable is extremely durable. You could probably do chin ups on it. Having said that, your bud did the right thing. They should be treated like they are bare and lethal.

If he raised the height of the garage, causing the drop clearence to be less than acceptable, the building inspector wouldn't necessarily know this. If he's having wiring installed in the garage, the electrical inspector should pick it up.

[Andy]

Andy comments:

In some areas of North Texas, a homeowner is permitted to do main service wiring providing the electric company approves the installation before connecting to the grid. No electrical inspector from the county is required... The electric company furnishes diagrams to the homeowner that specify what the required heights, clearances, specifications and materials are, and if all the rules are met, the company man will hook the grid up to the drop. I don't remember what the clearance above a roof has to be, but I know it is written down somewhere. And, yes, if someone is on that garage roof messing about, they can get hurt. Three feet sounds awfully small to me. From memory, it is something that a standing man can't conveniently bump into . However, in a drop I put into a cabin I have, the pipe comes up thru the roof and the mains go out over the roof from the pipe head to the pole, and it is only around 3 feet for about a 10 foot run along the roof That, however, is different from just running wires over a existing building... Be careful.

Andy in Eureka, Texas .... licensed PE (Inactive)

[aemeijers]

All it takes is one bad spot in the insulation, and a better path to ground. Guy with garage should request power company field super to come take a look at it. A heavy ice load, and a pole or weather head getting bent in the wind, and those wires could be laying on the shingles. Especially true in older parts of town where the drop may be

50+ years old. I've seen drops where you can see sunlight reflected off the power leads through the cracks in the insulation. All that is keeping them from shorting out is the chunks of remaining insulation acting as spacers.

My drop was moved when they did the addition, and they did not choose the spot real well. There is about ten feet of gutter where I have to be extremely careful when I am cleaning them each fall. I could kick previous owner for not spending the extra few hundred to put in buried service- it would have been a easy shot to the pole when they were putting in the driveway. Maybe better that he didn't, since he also cheaped out on the driveway substrate and dirt work.

[DerbyDad03]

re: "That, however, is different from just running wires over a existing building... Be careful.

Andy,

You seem to have missed the gist of my post. My friend isn't running wires over an existing building. In fact, it's the exact opposite. He re-built a garage under an existing service wire.

[Pete C.]

The service drop falls under the NESC vs. the NEC and the NESC is a pretty wishy-washy document. If it were my house I'd be complaining to the utility to get it the heck out of my way, though it would likely take a lot of bitching to get them to do anything.

There is a lot less danger than most people think, presuming this is a normal low voltage service drop. If it is a service drop, the maximum voltage to ground is 120V (240V is only relative to the other hot wire in the drop) and the drop wires normally have pretty rugged insulation.

I've done some tree work around the service drop at one house and had no issues pushing it up a bit with the aerial lift boom to get where I needed to go. I was careful not to slide the boom against it and risk cutting the insulation, I don't think the lift rental company would have appreciated a big melted arc mark on their lift.

[Tony Miklos]

First of all I think it's sad that the guy changed his garage plans to accommodate the existing line. I had a pole and line relocated and it cost me a about $300. That wasn't even essential to my new garage, I had the pole moved to improve my view of the mountains. If I had to do it over I'd do it again without a second thought. I never would have let a service drop cause me to make my garage ceiling only 8' instead of

10'.

As far as dangerous, sure it _could_ kill you, but you have a better chance of dieing from falling off the roof or ladder without even being shocked.