Using Trees for Wire Support

[dereckbc]

I can think of some articles that would not permit using a tree for overhead wire support, but I am looking for a comprehensive list. All comments are welcome.

 

[mtnelect]

This might help to explain, see attached picture.

 

[infinity]

Here's what I came up with when searching the NEC for "trees".

225.26 Vegetation as Support.
Vegetation such as trees shall not be used for support of overhead conductor spans.

230.10 Vegetation as Support.
Vegetation such as trees shall not be used for support of overhead service conductors or service equipment.

410.36(G) Trees.
Outdoor luminaires and associated equipment shall be permitted to be supported by trees.

590.4(J) Support.
Cable assemblies and flexible cords and cables shall be supported in place at intervals that ensure that they will be protected from physical damage. Support shall be in the form of staples, cable ties, straps, or
similar type fittings installed so as not to cause damage. Cable assemblies and flexible cords and cables installed as branch circuits or feeders shall not be installed on the floor or on the ground. Extension cords
shall not be required to comply with 590.4(J). Vegetation shall not be used for support of overhead spans of branch circuits or feeders.
Exception: For holiday lighting in accordance with 590.3(B), where the conductors or cables are arranged with strain relief devices, tension take-up devices, or other approved means to avoid damage from the
movement of the live vegetation, trees shall be permitted to be used for support of overhead spans of branch-circuit conductors or cables.

 

[mtnelect]

This might help to explain, see attached picture.

 

[dereckbc]

Infinity & mtnelect, thank you for your replies. I know 225.26, 230.10, and the luminary and holiday light exceptions. Just looking to see if there is something I overlooked. I withheld one piece of information that may change the subject a bit. 230.10 does not apply, not a service. It is a wire antenna using trees as support. The wire is hot with RF and spans some 140 feet.

I live in an HOA, and one of the residents, a ham radio operator, got caught using a dipole antenna using trees as support and concealment. Neighbors complained to CATV company their modems kept resetting, and guess what they found.

The association asked me if I knew of any code violations, and I deferred to research. I am certain he is not in compliance with 810.16(A) because he uses THHN wire as the antenna. What I question does 225.26 apply? It is not an Outside Branch Circuit, or is it?

I can read 225.26 two ways. Since it is for Outside Branch Circuits, it does not apply to an antenna. OTOH the wording "Vegetation such as trees shall not be used for support of overhead conductor spans". That says "Conductors," not Branch Circuits. Table 225.3 list other Article Equipment and Conductors, and 820 is one of them. What is the intent?

I should have said that earlier, my bad.

 

[mtnelect]

I think you are barking up the wrong tree !
From my perspective, Homeowner Associations have tremendous powers over their homeowners. I have heard some ridiculous requirements from them, but they have the power if the board approves them.

 

[letgomywago]

Stopping him from operating a HAM might violate the telecommunications act I've heard people trying to get back at HOAs with stuff like this so maybe make sure you're very isolated from the internal politics involved.

 

[zbang]

If the ham is operating within their license and their equipment isn't spraying harmonics all over the spectrum, the fact that the cable modems are resetting is the cable company's problem (not his). A possibly-non-compliant antenna isn't relevant to that. And using THHN, while not compliant with Art 810, is almost a non-issue in my (shirt-pocket) book.

A big question is whether the ham operator is willing to help track down other people's problems (some are) or is trying to be a jerk.

 

[infinity]

I can read 225.26 two ways. Since it is for Outside Branch Circuits, it does not apply to an antenna. OTOH the wording "Vegetation such as trees shall not be used for support of overhead conductor spans". That says "Conductors," not Branch Circuits. Table 225.3 list other Article Equipment and Conductors, and 820 is one of them. What is the intent?

Article 225 does not cover antenna wiring. You would need to find the prohibition in Article 810.

ARTICLE 225 Outside Branch Circuits and Feeders
225.1 Scope.
This article covers requirements for outside branch circuits and feeders run on or between buildings, structures, or poles on the premises; and electrical equipment and wiring for the supply of utilization equipment that is located on or attached to the outside of buildings, structures, or poles.

 

[don_resqcapt19]

Infinity & mtnelect, thank you for your replies. I know 225.26, 230.10, and the luminary and holiday light exceptions. Just looking to see if there is something I overlooked. I withheld one piece of information that may change the subject a bit. 230.10 does not apply, not a service. It is a wire antenna using trees as support. The wire is hot with RF and spans some 140 feet.

I live in an HOA, and one of the residents, a ham radio operator, got caught using a dipole antenna using trees as support and concealment. Neighbors complained to CATV company their modems kept resetting, and guess what they found.

The association asked me if I knew of any code violations, and I deferred to research. I am certain he is not in compliance with 810.16(A) because he uses THHN wire as the antenna. What I question does 225.26 apply? It is not an Outside Branch Circuit, or is it?

I can read 225.26 two ways. Since it is for Outside Branch Circuits, it does not apply to an antenna. OTOH the wording "Vegetation such as trees shall not be used for support of overhead conductor spans". That says "Conductors," not Branch Circuits. Table 225.3 list other Article Equipment and Conductors, and 820 is one of them. What is the intent?

I should have said that earlier, my bad.

This system is covered by Article 810 and nothing in the rest of the code applies, even things in other Articles of Chapter 8, unless the language in 810 says the other rules apply.

 

[synchro]

Stating the obvious, the function of a transmitting antenna is to radiate RF energy, no matter what type of design or construction is used. And so if this is the main path that the interference is taking to the cable company system and their modems, then I don't see that the ham is really at fault. However, there could be unwanted common-mode currents on the antenna feed line that are getting back into the electrical system and any interconnected grounding over to the CATV system. If such conductive paths are the primary means that the interference is getting into the CATV modems, then there might be measures that could be taken that would minimize this.

For example, if the ham is not using a good current balun to feed the dipole then that will cause more common-mode current (CMC) to get reflected back on the feed line. Off center feeds will also increase the CMC. Common mode chokes at multiple points along the feedline could also be used (not just at one point because it might be located at a current minimum on a standing wave at the operating frequency).

As mentioned above, the cable company should also be investigating what measures can be done on their end to minimize the problem, although it's not likely that they're very competent to do so.

The SSB or CW used on lower frequency bands creates quick changes in the amplitude of the RF. In my experience it's likely that semiconductors inside the CATV modems are rectifying (i.e, detecting) this modulation of the RF envelope, which then causes logic errors and causes the modems to reset.

 

[tortuga]

I am certain he is not in compliance with 810.16(A) because he uses THHN wire as the antenna.

I think you mean 810.52, 810.16 is only for receiving. Also I dont think it's the intent to prohibit THHN from being used, its more the minimum size of the wire.

810.52 Size of Antenna. Antenna conductors for transmitting
and receiving stations shall be of a size not less than given in
Table 810.52.

 

[dereckbc]

I think you mean 810.52, 810.16 is only for receiving.

You are correct; both are essentially the same table.

Also I dont think it's the intent to prohibit THHN from being used, its more the minimum size of the wire.

I'm afraid I have to disagree; they prohibit the use of THHN or any other soft-drawn copper. Building power and lighting wire is not made to span distance unsupported without a messenger. Soft-drawn copper wire is prone to stretching and breakage if used to span distance. Life would be hard on sparkies if building wire used hard-drawn copper or copper-clad steel.

This system is covered by Article 810 and nothing in the rest of the code applies, even things in other Articles of Chapter 8, unless the language in 810 says the other rules apply.

I agree, Don, and why I asked as an open-ended question to make sure I was not overlooking something. I knew 810 was silent on the subject, which I think is an oversite. If a ham radio operator is running a legal limit of 1500 watts, depending on the impedance of the antenna, the voltages on the wire antenna exceed 300 volts. Even at 100 watts, exceed 50 volts to ground.

As mentioned above, the cable company should also be investigating what measures can be done on their end to minimize the problem, although it's not likely that they're very competent to do so.

They may not be competent, but they indeed found something. The CATV distribution pedestal is directly under the antenna, and the radio operator cox came straight down and used the CATV ground electrode to bond his coax shield. Additionally, instead of running the coax with the CATV to the service entrance to comply with 250.94, he ran directly to a room on the opposite side of the house and sunk a ground rod outside where the coax entered and failed to bond to the house GES.

As soon as the CATV disconnected his ground, all the neighbors' problems disappeared. There was a significant common-mode noise current. Now the only user having issues with the CATV and RFI is the ham radio operator with his misguided, outdated practices by placing himself in a noisy and dangerous ground loop he created.

However, I am staying out of it. There are enough code violations; I am not concerned about using a tree as support. I will let the HOA, CATV, and City worry about it. .

 

[don_resqcapt19]

...
I agree, Don, and why I asked as an open-ended question to make sure I was not overlooking something. I knew 810 was silent on the subject, which I think is an oversite. If a ham radio operator is running a legal limit of 1500 watts, depending on the impedance of the antenna, the voltages on the wire antenna exceed 300 volts. Even at 100 watts, exceed 50 volts to ground.
....

It might be too specialized to be covered in the NEC, but not sure where else it would be covered if it is not in the NEC. Most of the other documents that cover this issue would not be codes or standards that are adopted and enforced by an AHJ.
Maybe it should be added to the NEC.

 

[synchro]

...
I agree, Don, and why I asked as an open-ended question to make sure I was not overlooking something. I knew 810 was silent on the subject, which I think is an oversite. If a ham radio operator is running a legal limit of 1500 watts, depending on the impedance of the antenna, the voltages on the wire antenna exceed 300 volts. Even at 100 watts, exceed 50 volts to ground.

The high frequencies being transmitted can cause RF burns but not ventricular fibrillation in the heart, and so they're very rarely life threatening. That's because RF currents flow mainly on the surface of the body, and also because the electrochemical mechanisms in the heart cannot respond at anywhere near the cycle rate of RF.
In catheter ablation procedures, RF is used at sufficient power levels to cause RF burns within a beating heart in order to cure arhythmias.. The possible issues of concern there relate to the heating caused by the RF discharge and not to the electrical current itself.

Because of these factors, I don't think the voltage limits within the NEC are really applicable to RF applications.

 

[petersonra]

I think the only thing that matters is what is in article 810 because the code says so.


Article 810 is pretty clear about requiring the use of hard drawn conductors for wire antennas.

I find nothing in article 810 that prohibits using trees to support antenna wires.

However, if what he is doing is interfering with other people's cable modems, he might well be in violation of some FCC requirements, although it is also possible that the cable modems are not compliant with FCC requirements to reject outside interference.

 

[tortuga]

they prohibit the use of THHN or any other soft-drawn copper. Building power and lighting wire is not made to span distance unsupported without a messenger. Soft-drawn copper wire is prone to stretching and breakage if used to span distance. Life would be hard on sparkies if building wire used hard-drawn copper or copper-clad steel.

Yes that sounds like tough stuff to work with.
I took a look again at 810 and 810.11 is the section that addresses antenna material. 810.51 references 810.11

810.11 Material. Antennas and lead-in conductors shall be of
hard-drawn copper, bronze, aluminum alloy, copper-clad steel,
or other high-strength, corrosion-resistant material.

Then there is an exception for antennas up to 35 feet long

Exception: Soft-drawn or medium-drawn copper shall be per-
mitted for lead-in conductors where the maximum span between
points of support is less than 11 m (35 ft).

 

[petersonra]

Yes that sounds like tough stuff to work with.
I took a look again at 810 and 810.11 is the section that addresses antenna material. 810.51 references 810.11

Then there is an exception for antennas up to 35 feet long

That is not for the antennas themselves, just the lead in wires.

 

[mtnelect]

It's the Homeowners Association that can solve this situation, forget about any code that is in play.

 

[mtnelect]

If you Google "Homeowners Association" you will see the authority, they have:
1. Satellite Dishes
2. Christmas Lights on trees
3. American Flags