We've just always turned the crane off and have not had a problem.
Hello WeldinFool, where heat is not an issue using nylon slings will take care of electrical issues like you're describing. Otherwise, there are commercially available isolators to deal with it. I am not at my work computer right now or I could include a link, I've got one saved on it. You might try using the search function here as there might be some information from a previous thread. Good luck and best regards, Allan
Bradley,
Scott is so correct (sorry Allan
)
the way I was taught
kills 2 birds with 1 stone
no power, no short
no power, no nitwit trying to move the crane and someone gets hurt
hope this helps
sincerely,
Kent
use a short endless loop sling between your rigging and the crane hook, OR there is a commercially available isolator for this task.
Attach lead directly to the piece.
OH and it IS an OSHA violation to weld anything hanging from an overhead crane hook. And forbidden by ASME B30
just an FYI
At my old place of employment we did the same thing, just used a leather glove. This was because we had some high tech remote controlled cranes and were told the circuit boards up in the unit didn't like the current flowing through the crane or it would fry the board.
Dualie,
Could you provide the written OSHA requirement (restriction) that states it is a violation to weld anything hanging from an overhead crane hook?
Also the requirement (restriction) from ASME B30?
Thank you,
Robert
Ditto what John said...Ground directly to the work being welded so that the current path does not travel through the equipment looking for ground.
Any chains or cables that welding current travels through need to be discarded or proof tested by the mfg to make sure that are still safe to use as lifting devices.
1910.254(c)(2)(iii)
Chains, wire ropes, cranes, hoists, and elevators shall not be used to carry welding current.
Can't put my fingers on it to quote it from OSHA, but it used to say something to the effect that one of the items on the inspection check list was to remove from service any chain, wire rope, or sling that had evidence of welding current or heat.
3 larger companies I have been in lately have all gone to the 'nylon' (or whatever they are) slings between the chain sling ring and the hook to totally eliminate any chance of current going through electrical, bearings, etc.
Now, obviously the chains are still at risk and I have seen a couple of great examples of what not to do. Totally wiped out some expensive 'HEAVY' duty slings.
He Is In Control, Have a Great Day, Brent
Oh yeah!! I knew you guys would have some good information! Thank you!! I will be meeting with our Production Managers tomorrow, and will definitely share your suggestions. I'm personally hoping that they go with the Peerless hook isolators (thanks Allan!). Just so you know, you guys make me look pretty smart. What a great resource this forum is!
Hello WeldinFool, that works both ways for everyone on the forum. Regards, Allan
We have always used nylon slings
http://www.mcmaster.com/#slings/=wnhyco They make isolator crane hooks/shackles and best practice would be to use both. 95% of our lifts are with nylon slings so it's not even a habit change.
You might want to check NEC codes as well.
One danger is creating a potential loop for large welding currents over small ground wires in the electric system. ?
I would go with NYLON slings.
By Tommyjoking 
Date 04-10-2015 03:51
Edited 04-10-2015 04:07
It is simple, ground to workpieces and not to crane boom or anything else attached to said crane. Electricity/current from your welding will only flow from electrode back to shortest line to ground in relation to machine being used. So unless your ground is on the chains or on the crane itself you are doing no harm at all. The stupid stories of electricity from welding backfeeding thru heavy equipment are simply a product of DUMB welders grounding to tracks and then welding on booms. If your ground is hooked to the workpieces at the end of that chain you have ZERO ISSUES to worry with. It would be best if it was hung and the crane was shut down while welding because some of the electronics are sensitive to static buildups of charge...this is mostly true of older equipment (late eighties to about mid 90's) Modern equipment you will not effect at all using sensible techniques.
If you doubt my advice......I have over ten years in heavy equipment repair ( welding directly on them), I have a degree in electrical engineering (only an associates). 25 yrs of welding experience. Weld that piece up...just be carefull of where your ground is.
Just an aside if you really want to isolate a connection like that in the field. Carpet pad is easy to get and an excellent insulator. Its almost always an isobutane rubber dirivetive and chocked full of air holes,,,,go get a sheet of that and just put her in there and you will ALMOST be able to divert a lightning strike with about four layers of it.
Just a follow-up on my original issue: Our Production Department ended up going with the crane hook isolators. They have purchased one for each bridge crane in the shop, and also one for each jib crane that is located in a welding station. As I go through some of the responses I've received, it's pretty cool to see the differing opinions from people with different backgrounds and work situations. For example, using nylon slings in the field is definitely the best bet (I personally have nearly 30 years as an industrial pipe-fitter and am a certified rigger), but in a welding shop environment they do not last long, hence the use of chain slings on all of our cranes. Also, it would be the obvious solution to just ensure that the ground cable is attached to the piece being welded, yet when welding large pieces in a shop that are continuously being re-positioned during welding, it is quite easy for the ground to become disconnected, and yet because it is suspended from a crane that is attached to the building, and metal rigging is used, you can still arc right up and never realize that you are grounding through your rigging, through your bridge crane, and eventually through your building's AC electrical wiring right back to the welding machine. I've seen this happen more than once in a welding shop, and I've also seen electricians make a fortune replacing melted electrical wiring in the walls and conduits. Thanks again for all of your advice!
No offense but, it's not the ground cable... It's called the work cable... Please don't confuse it for a ground cable.
Respectfully,
Henry
