Grounding Trailers

[jmellc]

Got a call today to look at some work for a scrap yard. Said he has several Comex trailers & an office trailer, none are earth grounded. He is concerned about lightning, etc.

I'm looking at several issues, but it seems to me any metal building should be grounded whether wired or not. Anyone else deal with this issue? My thought is an 8' by 5/8 ground rod & #6 ground, with jumpers around door hinges & between any isolated parts. To do this at each trailer.

Thanks for your thoughts.

 

[renosteinke]

Why?

OK, if there's power, I see your point about them needing a ground rod, as a 'separate structure.' But we're not required to bang in a rod for a light pole, or even a structure with only one circuit serving it. As Mike Holt has often opined, adding a ground rod to a light pole accomplished nothing.

Bonding jumpers? Again, why? Not only is there already a connection through the hinge pins, etc., but where will the electricity come from?

Lightning? I submit that any lightning bolt that can jump across the 2000ft. gap between cloud and earth can easily jump any microscopic gap in the path between metal parts.

Do as you wish - I see no harm - but I'm not sure you're accomplishing much besides making yourself feel better.

 

[electricguy61]

Just a WAG: Could it have to do with the large electromagnets they use for moving cars and other ferrous metal around with?

I believe any trailer / outbuilding with more then two circuits is supposed to have a secondary grounding electrode, and if there's no water piped to the trailer, the ground rods would likely be the primary.

 

[iwire]

Got a call today to look at some work for a scrap yard. Said he has several Comex trailers & an office trailer, none are earth grounded. He is concerned about lightning, etc.

I'm looking at several issues, but it seems to me any metal building should be grounded whether wired or not. Anyone else deal with this issue? My thought is an 8' by 5/8 ground rod & #6 ground, with jumpers around door hinges & between any isolated parts. To do this at each trailer.

Thanks for your thoughts.

If it has no external power supply and it is sitting on the ground in my opinion it is grounded enough. I really see nothing to be gained by grounding a conex box. I definitely don't see a benefit of jumpers at hinges.

Office trailers with power supplies I instal grounding electrodes because IMO the NEC requires me too, I don't think they really make anything safer.