How high above a high voltage tower?

[modbuilder]

I need to run a Litchi mission in a couple of days that will cross high voltage transmission lines twice. I'm guessing that the towers are up to 150-ft off the ground, so I'll assume the lines are that high (yeah, I know they sag between towers). I know that those lines radiate EMF that will interfere with a GPS signal if I'm too close to them.

So..... how high above them do I need to go to avoid losing GPS? I'd rather not go to 400 feet AGL because the client wants video that is lower than that. Anyone have first hand knowledge or experience?

 

[dbyantis]

I have flown around high tension wires behind my house for years, year or so with Mavic,with no ill effect. I did have compass issues near the base of the metal tower. so I would say base your altitude on the height of the structures, wires and trees.

 

[modbuilder]

Good to know. Sounds like I may not have to worry about it much. Thx.......... R

 

[mnoutdoors]

I fly over a 500 KVA line all the time never a issue above it,they are protected above with the nutreal lines
I always stay 100 feet above on my way over them. Below them can have some interference if close

 

[modbuilder]

Excellent! Feeling better about this job. Thx............ R

 

[kidroc]

I fly near a small relay station with miles of High Tension lines never any problem with the mavic pro,

 

[petruce]

My second waypoint mission that I flew with the litchi app created a smooth turn from one waypoint to the next not realising that it was going to take me directly over the top of a tower. I missed it by about two feet and still no interference.

 

[Pekik]

6 feet aboove the wire with mavic pro, no problem so far, checking tower n wire condition

 

[dronerdave]

As a troubleshooter in the power industry, I'd suggest staying a reasonable distance away. While doing a transmission line inspection, one of the guys at work crashed the departments P3P when he got too close (about 3 feet) to a energized 70kV line. Larger voltage lines can have a huge effect. Most people don't know the difference between a 115kV, 230kV or 500 kV lines, much less distribution voltages. Weather also can make a huge difference on how far it affects some frequencies and electronics. To tell the truth I don't have a clue what the Mavic can handle in respect to various transmission voltages. I'm not gonna risk mine to save from from flying a few feet higher.
These guys ramble but are fairly on track with this video.

 

[modbuilder]

Wow. Super good info. Very helpful. Am feeling much more confident about the job. Will go out today and see how high those towers really are to help set up waypoints. I'll put one right over where I pass over the lines so I'll know what height it'll be at that point. Thanks gang. ............. R

 

[designit777]

I've flown close several times with no issues but one time got to close for comfort.

 

[modbuilder]

Mercy Designit! Under two sets and over one. It that was intentional, you've got more guts than I do.

I'd thought I would fly the mission on Sunday that goes over the high voltage lines, but the Wx is turning sour for that. It's a long flight and the winds are picking up pretty good as well as showers in the forecast. I thought I'd be able to post results of a successful flight, but it now looks unlikely for tomorrow. Maybe middle of next week.

Thanks all for the great info. Most excellent. ............R

 

[dvarapala]

I have flown around high tension wires behind my house for years, year or so with Mavic,with no ill effect.

So has Ken Heron:

 

[modbuilder]

Man, Glad I started this thread 'cause I'm learning a bunch about capabilities. Don't think I'd want the contract to do that power line inspection though.

I'm totally relaxed now about the video mission that I'll fly over the transmission lines. I did eye-ball the lines/towers today, and I peg them at about 150 feet AGL. Don't have much ground elevation change to worry about, but I'll set the initial flight at about 200-feet above the take off point for the first pass over the lines and see what it looks like.

Thanks......... R

 

[dronerdave]

We've use the Phantom around 230kV to inspect, but with that camera you need to get about 3 or 4 feet from any part of the structure and/or line to see what you're lookin for. When you get between phases, at times the quad has issues hovering even at distances up to 6 feet away. On one occasion the phantom shot straight up 10 feet on it's own and was flying like it was in ATTI mode. The company is ordering a M-200 IR/FLIR series to do serious line surveys and I guess it's designed to work around high voltages. I hate to give a true distance on what is safe cause to be that close to a line requires you to be certified to be there in the first place and no matter what you're flying, varying atmospheric conditions can change those distances. I understand many might think of a drone as a bird but it's not, plus you ever notice most birds won't land on an energized transmission line? If for any reason the line relays and somebody reports that you're zipping around a transmission line, I wouldn't want to be in their shoes. It can give the hobby a black eye even if the drone doesn't cause issues. I don't see any problems staying a safe distance away crossing or running parallel to a line, but the untrained public might see it a bit differently. Unless you are trained, don't assume the line voltage or even if it's energized or not. Just assume it's always hot. We have miles of dead line and other lines are routinely taken out of service for maintenance. If you really want to stay in compliance (as a non certified pilot) keep distances no closer than the chart shows. More is better. Now I'll have to admit just last week I pulled a bonehead move and ran my Mavic into an energized 70kV line. Knocked off my rear landing gear and had to land it in my hand. How embarrassing considering my job profile. The Mavic flew fine.

Maybe some have seen this video but here is a switch being opened under load just to show what high voltage can do.

 

[kidroc]

Frigg that i fly a good height over them though.

 

[dronerdave]

Frigg that i fly a good height over them though.

Ha, well in reality it would take a huge drone to bridge the gap to cause a cross phase like shown in the video. I think that video was a switch test & they all knew what was to happen. But it does show what potential high voltage has. On the other hand the clearance distances between lower distribution voltages is short enough that a mid wire strike can cause one phase to slap into another and possibly burn down. Birds and mylar balloons cause a lot of havoc. Even though a large transmission line wouldn't budge much from a direct impact with a small quad, it might damage or break strands in the conductor. It's one of the things you look for when patrolling a line and a very expensive fix. Chances are if you hit a tree it won't sue you. Use common sense and fly safe as possible. I didn't do that last week and I almost lost my quad

 

[modbuilder]

Just thought I'd update the thread. I flew the Litchi mission on Tuesday that traveled over the high voltage lines without any problems at all. Two crossings. About 50 feet above and absolutely nothing noticeable on signals or GPS. Really appreciate all the great info posted here. Best regards............. R

 

[Plonker]

This is flying under the 132kV lines in the paddock next to my work, no ill effects.