Lighting kills...

[tec0]

A few days ago "give or take a week" there was a report of people being killed by lighting while living in a tent on a construction site. This got me thinking as I know that shipping containers are used for the same purpose and I thought it would be a good idea to ask.

How safe is a shipping container? As we all know it is used on most building sites as storage and temp offices and even people sometimes use them to house workers. Now if you do plan to use a shipping container for let’s say an office what electrical requirements are there and also how do you keep yourself and your staff safe from lighting storms?

[pmbguy]

Shipping containers used as a shelter are generally safe concerning lightning. The conductor, in this case the container, generates an electromagnetic field. This confines the current to the outside of the container. It is called the “skin effect”. The current moves along the outside and into the ground.

http://www.lightningsafety.com/nlsi_pls/Container-Safe-Shelter.pdf

[adrianh]

aka Faraday cage....std 7 science

[tec0]

I build own and operate a rather large Tesla coil that I use for experimenting on various types of crystal. I know what a Faraday cage is. My question however is about the “electrical wiring” to make the electrical aspect safe for both the user and the structure while being hit by lighting. Example how would the earthing be done?

So basically what will the electoral setup be like?

[Sparks]

The containers which are electrically fitted, for whatever use, are supposed to be certified and if their earth continuity is not up to standard they must not be certified fit for use. Their supply should also be tested before being connected. If the supply does not conform to the earth loop impedance it should not be connected until rectified.

[tec0]

So the best bet is not to have such a structure then? I cannot find any information on the wiring setup. It’s a pity that there isn’t a list that a layman can use just to make sure that there equipment, and electrical is safe.

No one minds getting a contractor to do all the checks but what if the contractor skipped a step how would a layman know? Electrical writing is one of the most important installations one can do but if there is no additional information how will we know if it’s done correctly?

[ians]

There is you can buy all the books at the SABS offices, let me know once you understand all the technical jargon that goes with lighting protection.

[Jacques#1]

I would see it as a normal installation, but treat the walls as you would with an "overhead" connection on a corrugated roof. Basically, earth every junction box, electrical apparatus (steel) etc. in the system to the container (which should be the case if you screw eg. a surface junction box to the container wall, and install a steel socket outlet with a earth to main DB). Install earth spikes and "ground" the container ( this is where the overhead connection/steel roof bit comes in....), install surge arrestors (which in this case I guess would be crucial) and do a standard COC to SANS0142.

[tec0]

I would see it as a normal installation, but treat the walls as you would with an "overhead" connection on a corrugated roof. Basically, earth every junction box, electrical apparatus (steel) etc. in the system to the container (which should be the case if you screw eg. a surface junction box to the container wall, and install a steel socket outlet with a earth to main DB). Install earth spikes and "ground" the container ( this is where the overhead connection/steel roof bit comes in....), install surge arrestors (which in this case I guess would be crucial) and do a standard COC to SANS0142.

I think you are on to something here sounds about right. I it is just if you are going to sit in e metal box you want to make sure that you don’t end up being toast.

[Jacques#1]

I think you are on to something here sounds about right. I it is just if you are going to sit in e metal box you want to make sure that you don’t end up being toast.

I dont think so? The llightning should travel around the box and out. The same with the electrical equipment, electricity always follows the lowest potential, so if it is earthed properly, then the lightning should just go around.

2 facts that I find very interesting: The golfers that survive a lightning strike usually have something in common, they were wet, hence the lightning travelled around them and not through, they do however suffer burns.

The other is something that i did a few years ago to prove that you need earth to get electrocuted. I put a few planks on the floor, with a roll of silicone wire, had my safety shoes on. Climbed on the pile with a live wire in my hand, the other end in a plug. Told the guy to switch on the circuit.....nothing, didnt feel squat, proving (to me anyway, in a weird way), that electricity flows to earth, and wont sit in a general mass or something like the sort. I wont try this with anything over 500VAC though

[adrianh]

Here is a question, lets say you were to get very close to a 32KV line (you do not touch the line), would the electricity to induced on your body by the ionisation of the air around the cable or static electricity or simply by the magnetic field. There is a line that runs close to Grand West and I often pass by it. The sound that comes off the line, I suppose due to the ionization is very noticeable. I wonder what sort of effect the general electrical and magnetic discharge from those line have on animals.

[tec0]

A while back a worker had the misfortune to die due to an exposed electrical wires. The motor was a massive thing used a hell of a lot of power. The man brushed it not even touched it properly and it was game over. Was a sad day for everyone. The worst I ever saw was at a large transformer. My word two people where working there clearly visible on the security camera. the one ask the other to get something. As the second person walked away something happened to this day it is just beyond anything... There was a flash of light "discharge" and in a second a grown man fully dressed in PPE was gone. Only the safety boots remained. (true story)

That is why I ask when it comes to electrical power... Its a killer.

[pmbguy]

The other is something that i did a few years ago to prove that you need earth to get electrocuted. I put a few planks on the floor, with a roll of silicone wire, had my safety shoes on. Climbed on the pile with a live wire in my hand, the other end in a plug. Told the guy to switch on the circuit.....nothing, didnt feel squat, proving (to me anyway, in a weird way), that electricity flows to earth, and wont sit in a general mass or something like the sort. I wont try this with anything over 500VAC though

Correct. As you have proved for yourself you need to be earthed to get shocked. BUT dam dude you got big balls. This must have been after a bottle of Jack Daniels and a dare from your mate. Clearly your wife was not around or you would have had testicular swelling from her slapping you, trying to prevent you from your dangerous curiosity. Now that I think about it, it’s actually a good thing she was not there. If she was and she slapped your loins while you were touching the wires she would earth, shocking both of you and leaving you with boiled eggs.

[adrianh]

Correct. As you have proved for yourself you need to be earthed to get shocked. BUT dam dude you got big balls. This must have been after a bottle of Jack Daniels and a dare from your mate. Clearly your wife was not around or you would have had testicular swelling from her slapping you, trying to prevent you from your dangerous curiosity. Now that I think about it, it’s actually a good thing she was not there. If she was and she slapped your loins while you were touching the wires she would earth, shocking both of you and leaving you with boiled eggs.

Define "Earth" - what about a lightning strike between clouds, doesn't that occur because the potential difference is high enough for a spark to jump?

I suspect that you would have to be earthed if your potential relative to the cloud was neutral. What would happen if you were not earthed but you just played with a Van Den Graaf generator

[pmbguy]

Define "Earth" - what about a lightning strike between clouds, doesn't that occur because the potential difference is high enough for a spark to jump?

I suspect that you would have to be earthed if your potential relative to the cloud was neutral. What would happen if you were not earthed but you just played with a Van Den Graaf generator

Hey I just fix printers I am certainly no expert in the field but I think that when lightning travels from cloud to cloud its because of differing potential between the two being great enough for it to jump. Lightning works the same when it hits the ground, its because of the differing potential between the clouds and the earth. The stronger the current the bigger the gap is it can jump, so you might think you not earthed but if the current is big enough it will jump, so passop met daai genni