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.
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.
You probably should have got as far away as possible as fast as possible and skipped the rod IMO
I was worryed about my crane.
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
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.
Liebherr1160 is spot on... sit down and enjoy the show
Do you get the same result with dropping the chains / hook onto the ground?
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.
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..
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.
Just walking accross the living room carpet can give you a jolt.I can imagine what what a twinn rotor chopper would do.
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.
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.
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.
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 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 more.
What is a "TV"?
It is a picture box that we watch in the evening that latley has been giving bad news on the economy.I will skip it tomaro and go strait to heavyeqipmentforums.com.
Ah, good man. I don't watch the news, seems all that's talked about is how bad things are. I already knew that, don't need someone to tell me about it daily.
Talk about grounded ...theres approx 4.5 million new vehicles parked and stock piled ,world wide with no destination ...... but im not supposed to mention that
I can't think of a situation where it would be bad to ground a crane. If any of you guys ever get a chance to operate as a contractor or employee of an electric utility, you will see that they ground equipment with 2/0 to 4/0 grounds, tied to a buried ground grid or ground rod to give you a better chance at survival if you accidently make contact with an energized line.
Been there ...we pulled 12 km of transmission line through with 500 K alive on the pole line adjacent to the new tower's ...the tugger's we first closed of with snow fence with one opening ,the entrance ,approx 50 foot radius.. the entrance had a another 15-25 feet of leed on them that was built up like a corridor. it had rubber mat laid down in different thickness ..getting thinner as you go ,up until you got to the main part where there was a mesh laid down that was bonded to the mesh inside the fence ...once in the whole area was laid down with mesh ...this made sure that a guy was always at the same potential as the machine while in there working ... .. its the difference in potential that will kill you as the current disperses through the ground in gradients... under strict permit ..i had the opportunity to pull down an old and erect a new tower after we split two 500k lines to two outer pole's .. that was tense ..your used to working with a 15 man team ...coming down and going up there's only myself and two rigger's/signalmen ..the rest are tucked away in p/u trucks about a 100 feet away for safety.. but great experience.. in seminars and such with the utility....slo-mo footage of the ground under contact showed it vaporised at less than 5/10 of a second...the grounds will dispearse any static charge that may build up in the machine while its working ..reducing the risk of a man being hurt or killed by an accidental discharge.....in full on contact its useless.. Generally speaking : if ya heard the wap then dont move because your still alive ...if your buddy is down ..dont move say a prayer because he's most likely gone and you will to if you move ..... it sad but its how it is ...dont attempt rescue in a hydro situtation ..it will likely mean there will be two that need help or died ...
Rule of thumb i was told about lighting is RUN. in order to ground your crane from that amount of raw power would require a cable all copper 6" in dia and less then 4' long. This info came from an electrical friend of mine that teaches what to do when tangled in power lines. the 650mcm cable we used to ground my old water well pump rig snapped like a toohpick at half the voltage of normal power lines (high voltage). the voltage can travel up to 50' in the ground surrounding the crane or equipment. I was shown that hopping like a retarded bunny rabbit away from your rig is the way to do it. Now thats only on normal high voltage. Lightning is a strange animal in that it will travel where ever it wants and how it wants. no way to protect from it and surely cant out run it. all i was told to do i safely rig it down in a hurry put the boom as close to the ground and run your block in the dirt then hit the ground running. hopefully the crane grounding itself would cause less damage and less fire. I have attended many safety classes for MSHA and CAL-OSHA classes for the last 10yrs, and the only thing that woke me up is to see my old POS rig boom up into a live power line. even though it was a controlled enviroment, i had to change my shorts. nothing we did would no start the derrick on fire. and it almost certain death to who freaks out on the controls. Hotdogs and a head of lettuce was posted at spots where the operator and the oilers would be standing on this pump rig and all of us would be fried. The hotdogs blew up and the lettuce looked like a peach pit. Just so you know the power was 20k volts on 3phase lines. so normal over head power lines....at least for california. Oh and learned that when the power trys to restart itself as fast as 30seconds later when the auto breakers kick in, it zaps you again....... anyone learn anything or am i just spinning my wheels?
Nope your right on ...the power can restart after it kicks out ..but now heres where people go wrong...the default number of times it will start and stop is preset but the utility..only the controller really knows ... which is why with a utility they have to apply and obtain a permit with a hold-off...meaning in the event that contact is made, once the breaker trips thats it ...it wont restart untill everyone has been contacted and the problem addressed.... the reason for a restart in the first place is in the event of a forigen object gets on the wire ..the idea is that the restart will blow it of ...again how many times the line will do it is up to the utility.... all the more reason that the electrical utility should be notified if the work space has overhead in it ....
i know this is an old post, but i would like to add that the utility crane ops that we work with have instructed us to fasten the ground cable to the rotating upperworks to protect the computer electronics from induced currents from working close to high potential voltages in switchyards, etc. (obviously you can't rotate continuously but that usually isn't a problem as you are working in a confined area). they require 1/0 welding cable for the ground. thanks, tom.
Yikes, I would hate to forget about that and get tangled up. I'm actually surprised they have you do that because regardless at that point when working near that type of equipment you will surely get some sort of static electricity anyway. Electronics on any car or equipment is 12 or 24 volt dc most of the time and it can handle it. I'm sure other operators have experienced it when to close to power lines of high voltage, if anyone touches the headache ball or sometimes just an outrigger they get the zap like when your a kid running around the house with socks on. Only time I ever had an issue was after an actual lightning strike. Since my last post, I was setting light poles at a park an on a clear day in the mojave desert my guys kept getting the zap. About 20 mins later clouds rolled in and I realized it was the static electricity from the approaching storm. as i started to lower the boom and shut down for the day I was struck. My ears rang for a bit and scared the socks off me. Crane took a couple of minutes to restart and gauges were all off. Changed a fuse and went on about my day. Sitting on outrigger pads, there was still a burnt spot on one wood pad where while rigged up I guess it sank in the dirt some where the metal foot was touching some dirt. That crane was a brand new grove rt 60t.
static when you ground the upperworks of the crane, workers will not get shocked by static electricity from impending storms, or static charged areas such as transformer installations, switchyards, and some broadcast antenna areas. the ground constantly dissipates the static electricity picked up. your lmi also stands a better chance of survival, doesn't take much to fry a circuit board, most internal computer circuitry uses 6v or less. your'e fortunate all you did was blow a fuse after that lightning strike. regards, tom.
Yes I know that this is an old thread but I just started reading it. I am a Telcom worker. I live in central Florida, which is lightning capital the world A radio tower is very much like a crane and yes they are seriously grounded, but the grounding is to make the tower look invisible to the lightning. In the case of the original question; I would and have stuck my bucket or the tip of my boom, on or in the ground, to get some kind grounding. Then I have gotten away to something that was sitting on rubber, like a car, truck, or in a the building. I would like to caution crane operators that when working around radio antennas that are admitting a good deal of power, that they should ask the station to turn down the power or even turn them off to protect personnel. this also protects their equipment from high reflection. Also the dangers of working around an AM station are different. RF will give you a burn, unlike electricity which tends to shock you. RF will burn with a very hot arc.
In my observations it is generally accepted that with modern cranes a soft sling must be used in the rigging if placing a piece of steel that is to be welded, to protect the cranes electrics from the welding current. Does a lightning strike damage the electric circuit boards like welding supposedly does? Is it necessary to isloate the crane from welding to avoid damage or is it just an old wives tale? Has anyone had a electrical computer or similar failure that can be directly blamed on welding?
I'd say it's an old wives tale, but better safe than sorry.
I had it once a couple year ago. Me and another guy were hooking up a silo to get tipped up and set in place......tail crane was already hooked on...we could just see dark clouds off in the distance....(usually doesnt take long to tip a tank and set'er down) figured we had enough time to get the job done..(more so bosses decision than our own)....well wrong-o....it blew in pretty fast....i just grabbed onto the cables/shackle to hook'er on...just outta the corner of my eye i seen a flash, thought for a split second it was a guy welding but nope....lightning had struck off in the distance...the static in the air went down the boom, threw the block and into the cables i was grabbin' onto and shocked me like crazy....felt like i grabbed onto a high powered cattle fencer......me and the other guy looked at eachother like oh sh*t....we quick ran to both cranes and sucked'em both in boomed'em all the way down just in time for it to start down pouring...........lightning is always a concern but gittin' zap like that definitely gives a guy a whole new perspective on how careful you should be and how not to take it lightly.....