Power line mast strike

[gonesail]

Originally Posted by keepondancin

Should be happy you're not dead.

yep .. what he said. power lines are certainly a sailor's nightmare. I scraped one once and only lost the windex

[DEAN2140]

That's what I call a comprehensive and well written answer. Kudos!

[Mauruuru]

It is unlikely that the line flashed to a mast mounted antenna 10 feet away. The dry air dielectric strength for a point (like antenna) is around 20kV per cm. For a 138kV line thats about 3 inches. Even in humid salt air its reasonably high but assume its only half thats still only 6 inches or so a long way from a 10 foot arc. Of course, once an arc occurs, it takes very little to sustain it but the thought that a flash of 10' could occur is unlikely since the phase to phase spacing of the lines can be closer than that and the voltage gradient is much higher than the gradient to ground.

[wsmurdoch]

OSHA says for work near a power line:

§ 1926.1409 29 CFR Ch. XVII (7–1–12 Edition)
TABLE A—MINIMUM CLEARANCE DISTANCES
Voltage (nominal, kV, alternating current) Minimum clearance distance (feet)
up to 50 .................................................. .................................... 10
over 50 to 200 .................................................. ........................... 15
over 200 to 350 .................................................. ......................... 20
over 350 to 500 .................................................. ......................... 25
over 500 to 750 .................................................. ......................... 35
over 750 to 1,000 .................................................. ...................... 45
over 1,000 .................................................. .................................. (as established by the utility owner/operator or registered professional engineer who is a qualified person with respect to electrical power transmission and distribution).

[windcastle1]

Insurance will pay for the damage regardless as to who is at fault. The difference is if the insurance company cannot collect for damages then the policy owner will be charged for the accident and we all know what that means!!!

[Montanan]

Originally Posted by wsmurdoch

OSHA says for work near a power line:

§ 1926.1409 29 CFR Ch. XVII (7–1–12 Edition)
TABLE A—MINIMUM CLEARANCE DISTANCES
Voltage (nominal, kV, alternating current) Minimum clearance distance (feet)
up to 50 .................................................. .................................... 10
over 50 to 200 .................................................. ........................... 15
over 200 to 350 .................................................. ......................... 20
over 350 to 500 .................................................. ......................... 25
over 500 to 750 .................................................. ......................... 35
over 750 to 1,000 .................................................. ...................... 45
over 1,000 .................................................. .................................. (as established by the utility owner/operator or registered professional engineer who is a qualified person with respect to electrical power transmission and distribution).

Thanks for providing that guidance schedule.

Per a FPL transmission line map the power line at Cocoa appears to be a 230 kV line so one should keep a minimum of 20 feet clearance distance.

This minimum distance is consistent with the associated Code of Federal Regulations section pertaining to equipment operated below a power line:

For equipment with non-extensible booms: The uppermost part of the equipment, with the boom at true vertical, would be more than 20 feet below the plane of the power line or more than the Table A of this section minimum clearance distance below the plane of the power line.

(iii) For equipment with articulating or extensible booms: The uppermost part of the equipment, with the boom in the fully extended position, at true vertical, would be more than 20 feet below the plane of the power line or more than the Table A of this section minimum clearance distance below the plane of the power line.

Should never bring a tall mast near a power line.

[s/v michaela]

You will never see it jump like that,,,, but working clearances are there for just that... work.
I have written many cease and desist orders for crane operators. The work clearance has a lot of safety factors built in.
If you want to really visualize the actual phase to ground clearance then just look at the pole/tower holding the line and "Stretch out the wrinkles" in the insulator. Now cover them with salt and pollution and watch them track at night,,,,, We wash them off with high pressure DI water every now and again to keep them from flashing over and tripping the circuit.

[belizesailor]

Originally Posted by 4palmer

Hobie Cats, drag up to beach, hit power line while holding aluminum frame. Bad Outcome. Hobie, rasing mast...hit power line while holding aluminum mast while raising. Bad outcome. Hobie put mast up get in car, back down ramp, hit power line....get out of car approach boat while its touching power line...Put hands on aluminum frame....Stomach blows out from power surge.

Friend of mine and a buddy were rigging a Hobie in a parking lot. Mast got away from them and reflexively they tried to catch it...just as it hit the power line.

My friend lost part of one arm from mid forearm down. His buddy died.

[sailasia]

I was working at Norseman Marine as a rigger in 1997 in Fort Lauderdale. A custom 90 foot sailboat named Iemanga hit the power lines about a block up the New River. It sounded like a huge explosion. The boat caught fire briefly and the engineer was lucky to live as he was blown into the headliner head first near the shaft as the floorboards threw him upwards. The power went out in half the city. They came to our dock and the damage was insane. We pulled the carbon rig and it was burned and cooked at the spot it hit. The rig was condemned. Very interesting damage. For instance the harken spinnaker pole track being aluminum was intact but every stainless bolt holding it on was melted like butter spewing metal splatter on the deck. The big shackle holding up the furler was cut as if by a torch. It landed on the deck. We fabricated a new rig and installed it. There was a power line on the way out that they passed under but it was close going out. We put a rubber garbage can on the top of the rig to prevent arcing and our crazy but incredibly talented head rigger Brad Storm was up in the bosun's chair to judge if the boat was far enough under. We left a low tide and heeled the boat over and pulled as far to the bank as depth would allow to get under the higher portion of the lines. They are hard to judge and measure because weather/humidity can droop the lines. I actually dated the stewardess from RI on that boat after that for a while. I miss the good old days.

[cdy]

I am a bit perplexed by this - I have kept a boat in the anchorage just south of the bridge ( HWY 520) - there a very large platforms for the poles and wires - obviously they are on the charts - but more importantly they are highly visible - unless traveling at night - if you have a big stick and traveling the ICW - I would think one would be keenly aware of mast height and possible issues - maybe this the same as tourists here in Orlando - paying too much attention to the car's GPS and not actually looking at the road enough

[Group9]

Sometimes, when you screw up, you just have to admit that it's your own fault.

I think this is going to be one of those times.

[belizesailor]

Originally Posted by sailasia

.... We put a rubber garbage can on the top of the rig to prevent arcing and our crazy but incredibly talented head rigger Brad Storm was up in the bosun's chair to judge if the boat was far enough under. ...

Ive seen people go up the rig to judge clearance on the Rio Dulce where we have some lines that droop lower than a very close by bridge (and current running under the bridge to make it more fun). Incredibly foolish. Im always baffled when I see it...how could someone be so stupid and the captain be so irresponsible.

Zap! Oops got to close, bosun is BBQ, who's next? [emoji15]

[belizesailor]

Originally Posted by Group9

Sometimes, when you screw up, you just have to admit that it's your own fault.

I think this is going to be one of those times.

Yeah, hopefully the OP will discuss with a competent attorney who will warn him off of this foolish action. As posted earlier (by a former lineman IIRC), I think the most likely result is that the OP will get sued for damages and likely lose.

Ive seen similar cases with bridge collisions. One owner who hit a bridge was making a big bluster about suing the bridge tender for not opening. It was a big deal...lots of officials showed up from various agencies. USCG officer clarified the situation for the owner...he didnt talk much after that...probably contemplating his future bankruptcy.

[mikedefieslife]

Originally Posted by Bill6878

Has anyone experienced an electrical strike from an FP&L power line in Cocoa FL?
I recently did and was looking for information on contacting a lawyer to sue for damages. There are no markings or warnings about mast height safety in the anchorage with sailboats anchored on both sides of the power lines. My mast did not touch but my antennas might have. I have heard that the power from the high voltage lines can jump 10’ to a mast. All my electronics were fried, multiple fans, relays and wires burned up, mast and stays damaged and in need of repair. Quotes over $150,000 in repairs. Still waiting on insurance to reply to my claim.

Why is the first thought to sue for damages rather than contacting the company and your insurance to ask the power company to pay for repairs. Surely suing is the last resort.

[capn_billl]

Originally Posted by Mauruuru

It is unlikely that the line flashed to a mast mounted antenna 10 feet away. The dry air dielectric strength for a point (like antenna) is around 20kV per cm. For a 138kV line thats about 3 inches. Even in humid salt air its reasonably high but assume its only half thats still only 6 inches or so a long way from a 10 foot arc. Of course, once an arc occurs, it takes very little to sustain it but the thought that a flash of 10' could occur is unlikely since the phase to phase spacing of the lines can be closer than that and the voltage gradient is much higher than the gradient to ground.

WAY too low.

In clean dry air, I have measured in low humidity a 1 inch arc with 10,000 volts.

That's about 4KV per CM, IN DRY AIR.

Add a little humidity, some mist, some salt air, (salt water is a VERY good conductor), and you can easily triple, or quadruple the arc length.

That makes a 6 ft arc at 200KV easy in the sea air. Then add to that AC voltage is measured by the RMS voltage, NOT peak. multiply by 1.7 to get PP Voltage, (which is what starts the arc). Once the arc is established, it ionizes the air, which then also becomes an excellent conductor.

Once the arc is established it can take 3 or 4 times the distance to break it.

Watch a Jacob's ladder for an example. They are usually run off of a 5-7kv Neon sign transformer, notice the arc starts at 1/2 inch at the bottom, and extends to 4 or 5 inches at the top. This is at 5KV, do the math.