Hope it dosen't happen!To anybody,

Submitted: Saturday, Jan 08, 2011 at 21:32
ThreadID: 83528 Views:3115 Replies:3 FollowUps:6
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But if you have a incident where as a live power line comes down over your vehicle, in a storm for example it catches fire, you have bugger all time to get out , Some say never run, Just walk very slowly, That would be hard!!.

If no fire just sit there??

Are the tyres enough to insulate you??

Saw a truckie with a tri axle trailer tipping a load of gravel a few yrs ago, Not watching what was going on and hurled it up into some major hi tension wires.What a noise that made!!, actually blew four tyres off rims, But he lived to drive another day.

Not a nice thing to think about, but theres obvisouly a wrong way you could go here,

Cheers Axle.

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Reply By: BuggerBoggedAgain - Saturday, Jan 08, 2011 at 22:03

Saturday, Jan 08, 2011 at 22:03
Been there, done that.

1st Incident
Those big black cables in industrial areas, strung between poles, well, the one in Coffs Harbour industrial area, just past the fruit stall opposite rail-line, was delivering to TWS and my exhaust caught the cable and brought it down, that green electrical box up on the pole exploded and I blacked out every business in the area.

2nd Incident
Bega Post Office, was going around the block, same exhaust, blacked out PO and every house with-in 2klms.

3rd Incident was driving down a Burwood street in Sydney when I noticed an Italian running/chasing me down the street, yelling out
stoppa your truck, stoppa your truck waving his arms and pointing up, I stopped and opened door and looked up, every phone cable on that side of street was wrapped around exhaust pipe.
I said telephone Telstra on phones in front of truck as the ones behind me are disconnected, LOL LOL

Country Energy, Australia Post and Telstra all sent bills to my boss, thousands of dollars, he politely informed them that ALL CABLES in NSW must be 4.5 mtrs off the ground and since the truck is legal at 4.3 mtrs to take a flying hike.

Those 3 stick in my mind, there are countless other incidents where I brought down power lines or backed on to them, when will utilities learn, height height height, 4.5 mtrs,no more-no less.
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Follow Up By: Gramps - Saturday, Jan 08, 2011 at 22:44

Saturday, Jan 08, 2011 at 22:44
Please don't drive through any of our tunnels LOL
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Reply By: Lex M (Brisbane) - Saturday, Jan 08, 2011 at 22:09

Saturday, Jan 08, 2011 at 22:09
If the power wire is on the vehicle you should be OK. You're like a bird sitting on a live wire. No circuit, no problem. Best thing to do is stay there touch nothing metal.

If you have to leave the vehicle jump out making sure you are not touching the vehicle and the ground at the same time.

If you can it would possibly be safer to drive away from the live wire rather than get out of the vehicle.
AnswerID: 441171

Reply By: Rockape - Saturday, Jan 08, 2011 at 22:16

Saturday, Jan 08, 2011 at 22:16
from what I understand if the vehicle/caravan or trailer is on fire you naturally have to get the hell out of there, you then have to hop down to the ground making sure you don't land on or touch the live cables, then keeping your feet together hop away as the difference between the voltage across the ground can be quite huge, say at the point you are at it is 5000 volts then 900mm away it is 3500 volts, the difference is 1500 volts which will make sure you don't live to tell the tale.

I have seen it with SWR lines (single wire earth return) where a mob of cattle all get fried because the difference between the ground voltage kills them.

Also when a large vehicle comes in contact with powerlines no one should go near it for 24 hours due to the risk of the tires exploding.

Have a good one

AnswerID: 441172

Follow Up By: Axle - Saturday, Jan 08, 2011 at 22:26

Saturday, Jan 08, 2011 at 22:26
Thanks for the info RockApe, It made me a bit curious about it all to.day when i spotted a car that had side swiped a power pole.

Cheers Axle.
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Follow Up By: Bonz (Vic) - Sunday, Jan 09, 2011 at 07:13

Sunday, Jan 09, 2011 at 07:13
Rockape is spot on, just get out and keep your feet together and hop away, if you have to, otherwise stay in the car till you're told the wires are dead. The voltage gradient Rockape talks about is called step potential, and it falls away pretty quickly, so just stay or hop, and I wouldnt be too worried about touching metal stuff in the car.

Never heard of the truck tyres thing above or of animals dying from step potential on SWER lines, but certainly from touching low live wires with their big fat noses, inquisitive things that cows are.
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Follow Up By: Rockape - Sunday, Jan 09, 2011 at 09:43

Sunday, Jan 09, 2011 at 09:43
for your info. If rubber tyred heavy machinery comes in contact with high voltage lines then it has to be left for 24 hours with an exclusion zone of 100 metres in case a tyre goes off. I had one go off (not due to high voltage) when I was in a shed about 60 metres away, that one landed a couple of large rocks on the roof. I will give you the drum it scared the living daylights out of me.

The cattle incident happened on a property south of McKinlay and I am told it was due to a bad earth at a transformer. Like you say cattle are inquisitive and have to all go over to see why their mates are taking a nap.

Have a good one.
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Follow Up By: Bonz (Vic) - Sunday, Jan 09, 2011 at 10:15

Sunday, Jan 09, 2011 at 10:15
Hmm interesting, I have seen heaps of trucks hit HV lines and no-one ever mentioned this tyre phenomenon. Thanx for the info.

I must have been a crook earth on the SWER line, must have been broken I reckon, but yes cows do have that wonder why theyre sleeping bent

All the best mate one learns all the time, after 30yrs mucking about with that stuff you'd reckon youd heard it all, now maybe I have.
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Follow Up By: Bazooka - Sunday, Jan 09, 2011 at 15:13

Sunday, Jan 09, 2011 at 15:13
Interesting posts, thanks all. Was curious to know the scientific reason for isolating the vehicles after ligtning strike or high voltage contact - plenty of info out there (PYROLYSIS).

This extract from the QLD NRME Dept:
"Tyres on trucks, cranes and other heavy vehicles may catch fire under a range of circumstances, with the obvious potential for the tyres to then explode. A lesser-known danger arises when the combustion takes place inside the tyre, with no external signs. Whenever excess heat is developed in or applied to a tyre, it can initiate a process within the tyre known as pyrolysis - the decomposition of a substance by heat.
This can cause a build-up of flammable gases and pressure within the tyre, which may ultimately rupture or explode. Enormous amounts of energy can be released by a tyre explosion, often leading to significant equipment damage, serious injuries or fatalities.
Pyrolysis related explosions are unpredictable, and have occurred immediately or up to 24 hours after initiation. An explosion can occur where no fire is visible and the danger area can be up to 300 metres from the tyre.
Tyre pyrolysis has occurred from welding on wheel rims, oxyheating wheel nuts, overheating brakes and wheel motor fires. It has also resulted from electrical arcing and current flow when rubber tyred vehicles have been involved in high voltage electrical incidents. Vehicles affected have included rubber tyred cranes and tip trucks, often as a result of collision with overhead supply lines. However, any rubber tyred vehicle involved in an incident where an electrical fault results in discharges or arcing around or through the tyres should be considered as a potential hazard."
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