One time I was doing a job on a high elevation,no trees around .Even boomed down I was the tallest thing around.A thunderstorm rolled up quick,I boomed down and drove a piece of re-bar in the ground and clampt it to the outrigger beam.I was sitting on wood cribbing.Was this right or wrong?I was conserned about lightning strikes.
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Grounding a crane
- Thread starter td25c
- Start date
willie59
Administrator
Well, I've never seen a scientific study on Cranes and lightning. But when your talking about lightning, I don't think there's such a thing as being wrong by being overly cautious about it. Not until someone can predict where lightning will strike. Is that like "when pigs have wings"?
I guess I was thinking about the way lightning rods work on a barn .The storm came up quick,lightning cracking all around ,hiar standing stait! I am sure this will happen again, spring is almost here.
I was worryed about my crane.
liebherr1160
Senior Member
25 c ...yup you were absolutly right in doing what you did ..
Heres how it works
...a crane on dunnage can and will become essentially a giant capacitor... Lets say you didnt do what you did ...there's unsettled weather in the air ..it is possiable for a man to sustain a leathal shock on static charge alone... it depends on a wide variety of factors ..the biggest being boom lenght. Like a magnet everytime you go through the electrical field the charge will become stronger ...until it goes through the wood or is discharged through the rigger when a man touches it..its not to be trifled with.... You can use the 30/30 rule ..less than 30 seconds between flashes or bangs put it down ...its up to you ...
Grounding the crane is not a sure fire means ...lets not forget the gradients that an electrical charge can go through when it hits as lightning,or a crane makes contact with hydro...you can still kill a man up to and beyond more that 100ft of the crane..
and get this ...the new modern day deal with microwave transmission's ,,kid you not ...i dropped my ball and a guy got his hand burnt from the charge ... i happened to be almost in the middle of a microwave tower triangle...go figure ...ground did nothing..clean dry poloyester and nylon slings were the order of the day ...apparently the site super knew and forgot to tell us ...
GEEZ thank's ...
And by the way ...you safer in the crane than anywhere in a storm like that ...roll upthe widows and watch the show
Heres how it works
...a crane on dunnage can and will become essentially a giant capacitor... Lets say you didnt do what you did ...there's unsettled weather in the air ..it is possiable for a man to sustain a leathal shock on static charge alone... it depends on a wide variety of factors ..the biggest being boom lenght. Like a magnet everytime you go through the electrical field the charge will become stronger ...until it goes through the wood or is discharged through the rigger when a man touches it..its not to be trifled with.... You can use the 30/30 rule ..less than 30 seconds between flashes or bangs put it down ...its up to you ...
Grounding the crane is not a sure fire means ...lets not forget the gradients that an electrical charge can go through when it hits as lightning,or a crane makes contact with hydro...you can still kill a man up to and beyond more that 100ft of the crane..
and get this ...the new modern day deal with microwave transmission's ,,kid you not ...i dropped my ball and a guy got his hand burnt from the charge ... i happened to be almost in the middle of a microwave tower triangle...go figure ...ground did nothing..clean dry poloyester and nylon slings were the order of the day ...apparently the site super knew and forgot to tell us ...
GEEZ thank's ...
And by the way ...you safer in the crane than anywhere in a storm like that ...roll upthe widows and watch the show
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I thought it was the right thing to do .I know thiers no guarantee where lightning will strike but I like to think at least I tryed to prevent it.I know this will happen again,I am going to carry a copper ground rod with the crane from now on.The situation with the microwave towers sounds spooky.Thanks for the advice.
AtlasRob
Senior Member
Do you get the same result with dropping the chains / hook onto the ground?
surfer-joe
Senior Member
I have seen a crawler crane or rubber-tired crane grounded, but it's unusual. (Corp of Engineers job) For one thing, they generally move around too much. For another, it's hard to beat tracks and outriggers as grounding rods, even if the rig is on cribbing. I've never heard of anyone being hurt by lighting striking a crane while inside the cab. Have heard of riggers and laborers being shocked whilst hanging onto the hook or cable or load when lightning strikes.
The microwave deal is interesting, fill us in on why that happens, Liebherr.
The microwave deal is interesting, fill us in on why that happens, Liebherr.
liebherr1160
Senior Member
yes . you could in a lightng storm...
but when working around powerlines with a utility under permit and hold-off's in place they are grounded by the chassis.
Surfer joe
what we were told was were were in a microwave field , current was being induced into the boom through electromagnetic waves ..not unlike working in the fields of transmission line's..polyester belts were used from the hook to the rigging ..nobody got a zap of any other part of the crane .. it just seemed that with the ball and the rope in the air it was going on ..scope it in,boom it down outa the fields it was gone
there were no seriuos injuries ..but a helluva wake up..
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surfer-joe
Senior Member
Hmmmm. I'll need to research that a bit. Probably well known by the folks that work with microwave towers and gear, but I never have.
Tell you what will give you a hell of a snap. When working with helicopters slinging up loads off a barge on open water to be hauled by air, there is a short nylon static strap that is to be rigged off the hook. Twin rotor machines are the worst. Anyway, the chopper builds up a big electrical static charge, and if you touch the hook or any part of the machine when it is hovering, you will get a pretty good jolt. Very unpleasant.
What you want to do is take the static sling the crew chief throws down to you, rig the lifting lines to that, then snap it onto the chopper hook, being very careful not to touch the hook. Even with that, I've seen and felt an electrical charge jump the static strap and use me for a ground sometimes. It's high voltage but small amperage and very unpleasant.
Tell you what will give you a hell of a snap. When working with helicopters slinging up loads off a barge on open water to be hauled by air, there is a short nylon static strap that is to be rigged off the hook. Twin rotor machines are the worst. Anyway, the chopper builds up a big electrical static charge, and if you touch the hook or any part of the machine when it is hovering, you will get a pretty good jolt. Very unpleasant.
What you want to do is take the static sling the crew chief throws down to you, rig the lifting lines to that, then snap it onto the chopper hook, being very careful not to touch the hook. Even with that, I've seen and felt an electrical charge jump the static strap and use me for a ground sometimes. It's high voltage but small amperage and very unpleasant.
liebherr1160
Senior Member
It would be interesting to get a telecomunication guy in here to offer an opinion .
My nieghbor had a 755 jd high lift dozer that broke down undernieth a high tension power line.It had transmission trouble.I had to remove the batteries to get to the problem.It was a hot summer day I was covered with swet.I would get a small jolt whenever I touched the dozer.It had to be from the power lines because I had removed the batteries.This is an interesting topic ,I think it should be disscused more.
liebherr1160
Senior Member
your not the first one to get a jolt ...according to Ontario Hydro (Hydro One) guys have been killed doing what you were doing ...
it makes for an interesting day
Hydro is not to be taken lightly...in any circumstance...
They had an instance about 5 years ago ..and in the history of hydro distribution yards what happened has never happened ...a guy was killed walking a catwalk behind the switches ...where it was suposed to be safe..its still being studied
You just never know.
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AtlasRob
Senior Member
Especially when you've forgot to take your work boots off!
Very intresting thread, something I have not encountered, thank goodness :drinkup
That jolt would be my wife kicking me in the rear after walking accross the carpet with mud on my boots.
OneWelder
Senior Member
Every once in a while you hear about an electrical engineer who has constructed a coil near high tension lines in order to steal electric power - One of them powered his house for over seven years, until a meter reader could not find a meter and turned him in
I assume that dozer worked like a poor coil.
I assume that dozer worked like a poor coil.
I have herd of this to,the way I understand it they run a line parallel to to the high tension line to conduct it.but who knows,it is an interesting topic.I am still trying to figure out if I will have TV reception after june 12 2009.I guess if I lose tv ,I will be on heavyequipmentforums.com more.