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Author Topic: line clearence  (Read 953 times)

David Allred

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line clearence
« on: October 31, 2019, 10:13:10 am »

This maybe should be in the basement, but also potentially useful within the intent of this forum.

I want to attach a "lean-to" to the side of my porch to cover my firewood stack.  My pole to weather-head house entrance power feed passes over part of a roughly 8ft x 8ft concrete pad.  I can run the roof slope in 3 of the 4 directions.  The preferred direction (function and appearance) offers the least clearance to the line.
I know that there must be regulations of some sort for this type of thing.  I have seen driveway vertical, horizontal to structure, etc, on-line, but then the power line, as it nears the house, gets within inches of the house.  What's the difference?
I said "lean-to" but it may or may not be attached to the frame of the house, if that matters.  Does it?
Firewood should have clued you in, but being rural, no permit or inspection required. 
Thanks for any input.
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John Roberts {JR}

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Re: line clearence
« Reply #1 on: October 31, 2019, 11:00:48 am »

You probably shouldn't touch the wires where rubbing against some structure could wear through wire insulation. Those drops are generally only 240V so not going to arc over like lightning across any modest distance.

I once had a lawyer try to hire me as an expert witness in court suing the utility when his client got shocked by bumping his aluminum ladder into a power drop... After I explained that his dumbass client had to literally touch the wire with the ladder to get a shock, my expert testimony was no longer required.  :o

JR

PS: of course free advice is worth exactly what you paid for it...
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Art Welter

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Re: line clearence
« Reply #2 on: October 31, 2019, 12:26:46 pm »

I know that there must be regulations of some sort for this type of thing.  I have seen driveway vertical, horizontal to structure, etc, on-line, but then the power line, as it nears the house, gets within inches of the house.  What's the difference?
I said "lean-to" but it may or may not be attached to the frame of the house, if that matters.  Does it?
David,

Seems Mike Holt has already answered the legal questions here:
https://www.mikeholt.com/mojonewsarchive/NEC-HTML/HTML/Article230-Services~20020219.htm

"230.24 Clearances

Service-drop conductors must be located so that they are not readily accessible, and they must comply with the following clearance requirements:
(A) Above Roofs. Overhead service conductors must maintain a minimum clearance of 8 ft above the surface of a roof for a minimum distance of 3 ft in all directions from the edge of the roof.

Exception No. 2: Where the voltage does not exceed 300V between conductors, overhead conductor clearances from the roof can be reduced from 8 ft to 3 ft, if the slope of the roof exceeds 4 in. in 12 in.

Exception No. 3: If the voltage between conductors does not exceed 300V, the conductor clearance over the roof overhang can be reduced from 8 ft to 1.5 ft, if no more than 6 ft of overhead conductors pass over no more than 4 ft of roof overhang, and the conductors terminate at a through-the-roof raceway or approved support. Figure 230-10 230-24Ax3.cdr

Exception No. 4: The 3 ft vertical clearance that extends from the roof does not apply when the point of attachment is on the side of the building below the roof. "


Although I personally wouldn't worry about the proximity of the overhead conductors any more than an extension cord, best to comply with the NEC, otherwise a sale of your property likely will require another renovation.

That said, in my experience, removing a woodshed is pretty easy compared to replacing a "dry well" with a septic system...

Cheers,
Art
« Last Edit: October 31, 2019, 12:29:12 pm by Art Welter »
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Erik Jerde

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Re: line clearence
« Reply #3 on: October 31, 2019, 03:13:55 pm »

This maybe should be in the basement, but also potentially useful within the intent of this forum.

I want to attach a "lean-to" to the side of my porch to cover my firewood stack.  My pole to weather-head house entrance power feed passes over part of a roughly 8ft x 8ft concrete pad.  I can run the roof slope in 3 of the 4 directions.  The preferred direction (function and appearance) offers the least clearance to the line.
I know that there must be regulations of some sort for this type of thing.  I have seen driveway vertical, horizontal to structure, etc, on-line, but then the power line, as it nears the house, gets within inches of the house.  What's the difference?
I said "lean-to" but it may or may not be attached to the frame of the house, if that matters.  Does it?
Firewood should have clued you in, but being rural, no permit or inspection required. 
Thanks for any input.

It's my understanding (which could be wrong) that the wire from the PoCo isn't covered by the NEC.  Those wires connect to your service drop wires.  It's at the point of the splice where NEC compliance begins and where the PoCo responsibility ends.  The PoCo is usually responsible for the splice BTW.  Call your PoCo and see what they have to say.  The PoCo power legs are insulated (or they should be, if not get the PoCo to replace them - they do that for free in my neighborhood).  The neutral line is the only one that isn't insulated but that shouldn't be carrying much (if any) current anyways if you have a proper ground at your service entrance.
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Frank Koenig

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Re: line clearence
« Reply #4 on: October 31, 2019, 04:25:14 pm »

It's my understanding (which could be wrong) that the wire from the PoCo isn't covered by the NEC.  Those wires connect to your service drop wires.  It's at the point of the splice where NEC compliance begins and where the PoCo responsibility ends.  The PoCo is usually responsible for the splice BTW.  Call your PoCo and see what they have to say.  The PoCo power legs are insulated (or they should be, if not get the PoCo to replace them - they do that for free in my neighborhood).

It probably varies by jurisdiction but this agrees with my experience in both the City of Palo Alto and Tuolumne County, CA. Check with the POCO.

Quote
The neutral line is the only one that isn't insulated but that shouldn't be carrying much (if any) current anyways if you have a proper ground at your service entrance.

This is false. The neutral and the parallel earth path between the earth grounds at the service entrance and the distribution transformer center tap together carry the difference current between the two hot legs, which can be as great as the full service current if all the load is 120 V and on one leg. As the ground path resistance is usually higher than the resistance of the neutral conductor of the service drop, most of this unbalance current flows in the neutral conductor. If everything is working correctly, however, the neutral should remain close to earth POTENTIAL as it's connected to earth ground at both ends.

--Frank

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David Allred

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Re: line clearence
« Reply #5 on: October 31, 2019, 04:46:22 pm »

For reference:
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John Roberts {JR}

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Re: line clearence
« Reply #6 on: October 31, 2019, 05:36:17 pm »

For reference:
Also be careful about stacking firewood, aka termite bait, near a wooden structure...

JR
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Tim McCulloch

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Re: line clearence
« Reply #7 on: October 31, 2019, 05:37:14 pm »

The PoCo drop is regulated by Code on the client end but not on the pole side.  In some jurisdictions the PoCo supplies the drop cabling and in others the homeowner must supply the drop.

Like Ivan says, "It depends..."
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Dennis Wiggins

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Re: line clearence
« Reply #8 on: October 31, 2019, 06:00:14 pm »

The neutral and the parallel earth path between the earth grounds at the service entrance and the distribution transformer center tap together carry the difference current between the two hot legs, which can be as great as the full service current if all the load is 120 V and on one leg. .

Just thinking aloud:  As household circuits are typically connected at random and the loads themselves intermittent, has anyone ever had a problem with too much current on the neutral?

Is it worth measuring under "full load?"

For the Homeowner?   Etekcity Multimeter MSR-C600
« Last Edit: October 31, 2019, 06:09:28 pm by Dennis Wiggins »
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Erik Jerde

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Re: line clearence
« Reply #9 on: October 31, 2019, 06:14:33 pm »

Just thinking aloud:  As household circuits are typically connected at random and the loads themselves intermittent, has anyone ever had a problem with too much current on the neutral?

Is it worth measuring under "full load?"

For the Homeowner?   Etekcity Multimeter MSR-C600

N conductor is the same size as H.  If one leg is fully loaded and the other is at 0 then youíll see full load on the N.  Add any load to the second H and the N load will go down because of phase cancelation.

Itís the same as shared neutral branch circuits.  You only need to oversize the N if youíre sharing N between ckts on the same H leg.
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Re: line clearence
¬ę Reply #9 on: October 31, 2019, 06:14:33 pm ¬Ľ


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