When Lightning or Electrical Storms Strike

[ChrisFishr]

Question is:

We were always told that old barns and so forth had lightning rods on the roof, so that the roof top appears to be at the same potential as the earth's surface or ground level. This makes it less attractive to the lightning.
We are and were also always told not to hold metal golf clubs on a golf course and to seek the lowest point on the ground during an electrical storm.

I have a trailer project I am designing and I thought it would make good sense from a safety point to include a cable/grounding electrode in the trailer.
That way if the trailer was parked out in a wide open space, such as a field, it would be safer in case of a electrical storm ? Please share your OP.

 

[LarryFine]

Actually, being at the same potential as earth would make the buildings more attractive to lightning. The trailer (its power source, that is) should be bonded to the chassis as well as earthed.

The rods' primary purpose is to reduce the likelihood of a strike by streaming electrons into the atmosphere, effectively "discharging the capacitor" before the voltage gets high enough to arc.

 

[quogueelectric]

They say on the history chanel that some scientists think the neuclear particle bombardment from the sun and outerspace is what may trigger ionized paths to ground to cause some lightning strikes to earth.

 

[LarryFine]

Want to see something even more amazing? Do a web-search for 'sprites' related to lightning.

 

[paul renshaw]

Actually, being at the same potential as earth would make the buildings more attractive to lightning. The trailer (its power source, that is) should be bonded to the chassis as well as earthed.

The rods' primary purpose is to reduce the likelihood of a strike by streaming electrons into the atmosphere, effectively "discharging the capacitor" before the voltage gets high enough to arc.

Maybe this is wrong, but we were taught that the closer to earth potential the less attracive to the lightning is true because as far as positive and negative goes the earth is considered neither, or neutral charge. And that lightning has a lot to do with proximity, when things become positively charged, if the lightning leaders, which are negative charge, are close enough to bridge the gap, you get the strike. In our substations we have the huge steel lightning masts towering over everything that are connected to a ground grid which is very close to earth potential, and rarely if ever do we get a lightning strike in the substations. If we ever do take a hit the first thing that is looked at is the grounding grid. I have been in a relay house in a 69kv substation during a horrible lightning storm and personally witnessed trees within 100 yards that were shorter than the lightning masts get blown up by the lightning. The trees had become positively charged with electrons and the negative lighning leaders bridged the gap of the potential difference, opposites attract. If the masts were more attracted to the lightning, why would they not get hit but the trees will? Maybe I understand it wrong, but it does not make sense to me to put something that would increase the potential for lightning strikes, or make it more attractive to lightning, inside a substation or other ares where you are trying to prevent a strike.

 

[nakulak]

when in doubt install an overhead grounding ring.

 

[bob]

Check this site. It gives the theory behind ltg strikes.
http://www.glenbrook.k12.il.us/GBSSCI/PHYS/CLASS/estatics/u8l4e.html

 

[paul renshaw]

It's always hard to predict or fight mother nature.

 

[jghrist]

The lightning rods on a barn and the lightning masts in a substation have the same purpose, to get struck instead of other, more vulnerable objects. They are solidly connected to good grounding electrodes so that they can get struck and safely conduct the lightning surge to ground. The barn roof, if struck, will catch on fire. Substation equipment and bus, if struck, will flashover and cause an outage.

Lightning rods and masts are more likely to get struck than surrounding objects because they are higher. If you see trees being struck outside the substation it is because they are far enough away from the masts that the masts do not protect them.

 

[paul renshaw]

Lightning rods and masts are more likely to get struck than surrounding objects because they are higher. If you see trees being struck outside the substation it is because they are far enough away from the masts that the masts do not protect them.[/QUOTE]

I agree, and that is why the masts are there, for lightning protection, and not attraction.

 

[Pierre C Belarge]

A well designed and installed lightning protection system is similar to a Farraday Cage. It will help to divert the lightning strike to the earth. It is not always successful...at that point hopefully the bulk of the strike will be diverted, causing less damage to the building/building contents.