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Thread: Lighting kills...

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    Diamond Member tec0's Avatar
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    Lighting kills...

    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 letís say an office what electrical requirements are there and also how do you keep yourself and your staff safe from lighting storms?
    peace is a state of mind
    Disclaimer: everything written by me can be considered as fictional.

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    Platinum Member pmbguy's Avatar
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    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_...fe-Shelter.pdf
    It is not the strongest of the species that survive, nor the most intelligent, but the one most responsive to change. Ė Charles Darwin

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    Diamond Member adrianh's Avatar
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    aka Faraday cage....std 7 science
    How easily someone is offended is directly proportional to how stupid they are.
    ~GS Elevator

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    Diamond Member tec0's Avatar
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    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?
    peace is a state of mind
    Disclaimer: everything written by me can be considered as fictional.

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    Gold Member Sparks's Avatar
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    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.

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    tec0 (01-Dec-13)

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    Diamond Member tec0's Avatar
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    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?
    peace is a state of mind
    Disclaimer: everything written by me can be considered as fictional.

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    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.

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    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.
    IJS Installations
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    tec0 (02-Dec-13)

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    Diamond Member tec0's Avatar
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    Quote Originally Posted by Jacques#1 View Post
    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.
    peace is a state of mind
    Disclaimer: everything written by me can be considered as fictional.

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    Quote Originally Posted by tec0 View Post
    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
    IJS Installations
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