Stay within Right of Way under which load cases. 1

[bacon4life]

In thread608-259312 it was mentioned that the NESC requires wires to stay within the the Right of Way under blowout conditions. What section is that specified in?

In sections 230-234 I see only references to the clearances between wires and various objects, but no mention of property rights. I have come across 4 different situations, but haven't found a code reason to justify any of them. Does anyone apply something besides option 2?

1. Keep the wires on your ROW under nominal conditions.

2. Keep the wires on your ROW under blowout conditions.

3. Keep the wires on your ROW under all conditions.

4. Keep the wires on your ROW under all conditions, with enough clearance that some could put a building on the property line and still meet rule 234 clearances.

In options 1 to 3, it seems like you are interfering with the adjacent property owners right to fully utilize their land.

 

[stevenal]

I am unaware of any such rule in NESC. The code deals with clearances, not the legalities of ROW agreements. Depending on the ROW in question, local ordinances or county or state statutes might apply, as well as the wording in the agreement itself.

Option 2 would certainly help with section 218 vegetation issues. Option 3 is impossible to achieve, since all conditions include airliner crashes, nuclear attack, and so forth. And option 4 seems like a good idea, since NESC is maintenance code that obligates the utility to maintain clearances no matter what the adjoining landowner might do on his land.

 

[bacon4life]

Option 3 would be very hard if you include things besides the design/weather load cases.

Option 4 sounds like a great plan, but for distribution and subtransmission on street ROW, it is already pretty difficult just to meet option 2.

 

[stevenal]

"Option 4 sounds like a great plan, but for distribution and subtransmission on street ROW, it is already pretty difficult just to meet option 2."

Won't it be more difficult to move the line when the adjacent owner starts building? The required setbacks may not be sufficient to maintain clearance.

 

[transmissiontowers]

We usually consider that the adjacent property owned might build up to the property line of our ROW, and I found this while searching the NESC:

NESC Rule 230 I. says:
Maintenance of clearances and spacings
The clearances and spacing required shall be maintained at the values and under the conditions
specified in Section 23 of the applicable edition. The clearances of Section 23 are not intended to be
maintained during the course of or as a result of abnormal events such as, but not limited to, actions
of others or weather events in excess of those described under Section 23.
NOTE: See Rule 13 to determine the applicable edition.

Figure 233-2 Point D specifies Final Sag, No Ice and a 6 PSF wind on the bare conductor at 60° F.

Section 234A2 says:
Horizontal clearances (with wind displacement)
Where consideration of horizontal displacement under wind conditions is required, the wires,
conductors, or cables shall be considered to be displaced from rest toward the installation by a
290 Pa (6 lb/ft2) wind at final sag at 15 °C (60 °F). The displacement of a wire, conductor or
cable shall include deflection of suspension insulators. The displacement of a wire, conductor,
or cable shall also include deflection of a flexible structure if the highest wire, conductor, or
cable attachment is 18 m (60 ft) or more above grade.

So the NESC requires that the wire when blowing out must consider the deflection of the catenary, the suspension insulator and the structure and maintain code clearance at 6 psf and not for the extreme wind from Rule 250C (abnormal event).

This is not to say that if a conductor blows out of the ROW during a hurricane and contacts a building and burns it down, you won't get sued by the owner.

_____________________________________
I have been called "A storehouse of worthless information" many times.

 

[stevenal]

At 1st glance it would seem the "actions of others" part might let the utility off the hook if the adjacent property owner builds so that clearances are violated. Depends on one's definition of "abnormal." This part is new for 2007, so perhaps a little research is in order. The 2007 change proposal refers to IR529. IR529 does not deal with building, but with severe weather, vehicle accidents, etc. At the end, the interpretation team says "Utilities are responsible for correcting non-compliant conditions—whatever the cause—when they have knowledge of such conditions.”

 

[bacon4life]

In Washington, construction workers/equipment must stay 10 ft + 0.4 in/kV over 50 kV. Thus if someone wants to put a building on the property line, the line needs to have clearance of 10 ft plus another couple feet for the workers and scaffolding to be on the outside of the building. Do you usually try to get that much land for both distribution and transmission?

I am under the impression that on the fairly rare occasion someone does want to build near our lines, they have paid us to relocate or raise the lines. While easy and more difficult are not directly related to money, having someone elses money to spend eases the burden a bit

 

[stevenal]

I wouldn't let OSHA clearances dictate, since most lines can be deenergized for scheduled building maintenance. Might be other reasons for such a wide ROW, though.

The non-utility adjacent property owner, not subject to an easement or ROW agreement, and not subject to NESC is not obligated to pay anything.

 

[MikeDB]

Neither the NESC or OSHA address required ROW, only the clearances to lines. Having a wide enough ROW gives the utility some control over the use of that land to maintain required clearances to the line. Without any land rights, a utility would have to raise their lines every few years as trees grow or would have to move the line if someone wanted to erect a building too close to the line. So the wider the ROW that a utility can get, the more protection they have, assuming proper wording of the easement.

The Rural Utilities Services recommends transmission ROW width to be wide enough to accomodate conductor blowout under NESC rule 250C Extreme Wind and still provide clearance to buildings. No distinction is made for rural or urban areas.

 

[transmissiontowers]

There are some new FERC rules that require utilities to have tree trimming plans in place for Transmission Rights of Way after the major Northeast Blackout (caused by a tree under a line).

I have heard (not sure where) that some states allow utilities to trim trees outside their ROWs on private property. We have always trimmed trees at the edge of the ROW straight up, but the new thought is you go straight up to some elevation and then at an angle into the private property.

_____________________________________
I have been called "A storehouse of worthless information" many times.