Grounding for lightning strike

[GCinSC2]

For your continued enlightenment, discussion or ?????

Mark Polk and Mike Sokol at 2014 Hershey RV show.

https://www.youtube.com/watch?v=xl76kLLvHOI

[JCWDCW]

[QUOTE=mikeoxlong;2380546]Another misunderstanding.
The standard 10’ ground rod does not direct a short in your home 120/240 volt electrical system to earth. Electricity seeks the path of least resistance back to its source. In your home that would be the transformer that feeds your electrical panel.[/QUOTE]
House power supply is typically grounded to the incoming water supply. If you have a well with plastic piping, then a ground rod ...actually several tird together in a loop....will be required.
Following from the web....home inspection site

Electrical systems must be grounded so that electricity can be harmlessly discharged into the earth. Grounding is an essential safety precaution to minimize shocks and prevent damage from lightning, short circuits and faulty wiring. Without grounding, the electricity is live and will transmit a charge to a person or object that comes in contact with it. This can result in an electrical fire or electrocution. The ground wire is the biggest electrical safety feature in a house. It services all of the electrical outlets and should also ground all of the light fixtures.
How Do You Ground an Electrical System?
The most common way to ground an electrical system is by attaching the grounding wire to the cold water pipe. In order to ground an electrical system, all of the white neutral wires are connected in the main service panel to a metal strip called a neutral bus bar. A 100 amp service requires a bare #6 copper grounding wire which runs from the neutral bus bar to the metal cold water supply pipe that goes into the ground. A 200 amp service requires a #4 gauge copper wire. The wire is attached to the pipe with a ground clamp made of copper, bronze or brass. The copper grounding wire is bare because it has no need for insulation since it is already grounded. When the water supply pipe is plastic, the ground wire runs from the neutral bus bar to a pair of metal rods outside driven four feet into the ground. This is referred to as a double ground. It is quite common in older homes to find the grounding wire connected to a metallic copper or galvanized plumbing supply pipe that is close to the electrical panel. Under today’s standards it is to be connected before the first shut-off valve leading into the house.
BTW the transformer on the pole is also grounded to a ground rod.

JCW

[John&Vicki]

Interesting but confusing thread. Here is what I think I learned:

(1) Disconnect your city power during a lightening storm.

(2) Get inside your Airstream during a lightning storm.

(3) Since Airstreams are made of aluminum they act as a Faraday Cage and you won’t be harmed.

(4) If your trailer is not grounded your electronic gear may get fried.

Correct?

Thanks,
John

[GCinSC2]

And lower TV antenna per video recommendation.

[BayouBiker]

Pretty close....

Grounded or not, your electronics may get damaged as he wimpy grounding is no match for a lightning strike, but only if the voltage is allowed to enter the electrical system. So....

In most Airstreams you cannot wind in the antennas instead you should disconnect the cable lead into the TV's. Harder to disconnect the audio system antenna... Disconnect the cable and internet connections while disconnecting shore power.

Also a lightning rod may not be worth the hassle of setting it up. It would help to have a stand alone rod or a rod that attaches to the tow vehicle and ground. But bear in mind putting the rod up will significantly increase the chance the rod and anything close to it will get a strike.

When boondocking, avoid featureless areas if a storm is possible. Instead park 20-100 yards from a feature larger than your trailer.

[AKmtnpilot]

I leave my tow chains spread out on the ground.

[mikeoxlong]

Originally Posted by JCWDCW

[QUOTE=mikeoxlong;2380546]Another misunderstanding.
The standard 10’ ground rod does not direct a short in your home 120/240 volt electrical system to earth. Electricity seeks the path of least resistance back to its source. In your home that would be the transformer that feeds your electrical panel.

House power supply is typically grounded to the incoming water supply. If you have a well with plastic piping, then a ground rod ...actually several tird together in a loop....will be required.
Following from the web....home inspection site

Electrical systems must be grounded so that electricity can be harmlessly discharged into the earth. Grounding is an essential safety precaution to minimize shocks and prevent damage from lightning, short circuits and faulty wiring. Without grounding, the electricity is live and will transmit a charge to a person or object that comes in contact with it. This can result in an electrical fire or electrocution. The ground wire is the biggest electrical safety feature in a house. It services all of the electrical outlets and should also ground all of the light fixtures.
How Do You Ground an Electrical System?
The most common way to ground an electrical system is by attaching the grounding wire to the cold water pipe. In order to ground an electrical system, all of the white neutral wires are connected in the main service panel to a metal strip called a neutral bus bar. A 100 amp service requires a bare #6 copper grounding wire which runs from the neutral bus bar to the metal cold water supply pipe that goes into the ground. A 200 amp service requires a #4 gauge copper wire. The wire is attached to the pipe with a ground clamp made of copper, bronze or brass. The copper grounding wire is bare because it has no need for insulation since it is already grounded. When the water supply pipe is plastic, the ground wire runs from the neutral bus bar to a pair of metal rods outside driven four feet into the ground. This is referred to as a double ground. It is quite common in older homes to find the grounding wire connected to a metallic copper or galvanized plumbing supply pipe that is close to the electrical panel. Under today’s standards it is to be connected before the first shut-off valve leading into the house.
BTW the transformer on the pole is also grounded to a ground rod.

JCW
[/QUOTE]

Yes, these instructions are correct. That doesn’t Change the fact that electricity seeks a path back to its source, not necessarily to earth. Your home is fed by the transformer, that is true. The path of least resistance in your home would be any part of the bonded ground in your home (Which leads back to the transformer). And yes, the transformer also has a ground rod, who’s useful purpose is to drain lightning/static to ground (back to its source?). If you we’re to measure the resistance between the ground rod at the transformer and the rod at your home panel you would most certainly find mega ohms, meaning it is not an effective path back to the source.
As I said before, someone always wants to disagree.

[BayouBiker]

To avoid further confusion, be aware that electrical power design for a home has different criteria than for a travel trailer. The principles are the same but the objectives are different. Without elaborating too much, just be aware that designs, practices and standards regarding neutral and grounding are different so be sure to apply home requirements to a home and trailer requirements to the trailer.

[Boxite]

This discussion reminds me of the cartoon I recently observed in-which some guy at a computer is texting his buddies saying, “It amazes me that all my on-line friends who LAST week were Constitutional Experts are now Infectious-Disease experts.”

The “electrical experts” in this thread are in complete disagreement with EACH OTHER so... how can they all be correct?

Some simple logic will tell you that if lightning is attracted to items connected to the Earth.... that it is a BAD IDEA to connect your Airstream to the Earth! Doh!
However, even if an Airstream, car, or airplane is NOT grounded...if it SHOULD get struck instead of some other grounded object nearby... the Faraday Cage effect would protect the occupants.

Faraday Cage! From an article on Faraday Cage: “ Automobile and airplane passenger compartments are essentially Faraday cages, protecting passengers from electric charges, such as lightning”

[mikeoxlong]

Originally Posted by Boxite

This discussion reminds me of the cartoon I recently observed in-which some guy at a computer is texting his buddies saying, “It amazes me that all my on-line friends who LAST week were Constitutional Experts are now Infectious-Disease experts.”

The “electrical experts” in this thread are in complete disagreement with EACH OTHER so... how can they all be correct?

Some simple logic will tell you that if lightning is attracted to items connected to the Earth.... that it is a BAD IDEA to connect your Airstream to the Earth! Doh!
However, even if an Airstream, car, or airplane is NOT grounded...if it SHOULD get struck instead of some other grounded object nearby... the Faraday Cage effect would protect the occupants.

Faraday Cage! From an article on Faraday Cage: “ Automobile and airplane passenger compartments are essentially Faraday cages, protecting passengers from electric charges, such as lightning”

UNLESS you are plugged into shore power, then all bets are off

[BayouBiker]

Shore power only provides an entrance to damage your stuff. But this thread is about boon docking so there is that....

[mikeoxlong]

Originally Posted by BayouBiker

Shore power only provides an entrance to damage your stuff. But this thread is about boon docking so there is that....

Well then, I retract my useful information.

[DC Bruce]

I’ve been close to lightning twice. Both experiences were interesting and instructive. First, lightning struck a wood utility pole at the street end of my driveway. The pole was fairly closely (15’) surrounded by much taller trees. The pole did not carry power conductors, only cable TV and telephone. The strike it the top of the pole and then traveled about 6 feet down to a metal crossbar that had been carefully grounded. I know that because about a 3/4 deep vertical splinter was stripped off the side of the pole until the metal crossbar. My takeaway: if a lower pole is better grounded than a nearby higher one, don’t assume that you’ll be protected by the higher object, if it’s a tree.
#2- Different house. There was a very tall oak tree about 15’ from the corner of my 3-story plus attic house. The tree was still taller than the peak of the roof. About 10 feet up the tree, there was a spotlight powered by a cable enclosed in aluminum conduit. The conduit went down the tree and under the ground, entering the house somewhere. Near the back door was a light switch that controlled the spot light. Lightning struck the tree and travelled down trunk to the conduit. The strike bent the metal switch plate cover inside the house and tripped the breaker at the panel. The breaker was destroyed, but other than that and the bent switch plate, there was no damage to the wiring or any appliance or electronics in the house. I think I had to replace the wall switch by the backdoor, too. My takeaway: even though one would expect the aluminum conduit underground to dissipate the strike, enough of a current was induced in the wiring to cause damage to the components carrying that current (the breaker and the wall switch).
A former sailor, I know of a boat with a metal mast that was “bonded” to the metal through-hull fittings in the fiberglass hull. A lightning strike on the mast generated so much current that the through-hulls got hot enough to melt the fiberglass and fell out. As a result, the boat sank.

[NevadaGeo]

For whatever you might take from it. Years ago I was doing welding inspection around the Hawthorne Army depot in Hawthorne Nevada. Steam pipe lines. They had no direct flame of any kind in these buildings because everything in the building would go boom. Every corner of these buildings had on top what looked like chimney cleaner b rooms with hundreds of small metal spikes sticking up. I drove by during a lightning storm and those chimney cleaner brooms were buzzing. The folks that designThose buildings probably had a good idea how to keep them from being hit by lightning with the witches broom.

[2MileHi]

Don't need no stinkin ground rods. I'm safe sitting on my rigs tires. And metal stabilizers. And tongue jack. So as a practical matter, Aren't we always grounded? I won't bore you all with my boating adventures on the Chesapeake!

[johnrobison]

My first career was designing power systems and lightning suppression for commercial and military systems, and I will offer some thoughts based on that experience

First to speak to the question of grounding. Should you have a ground rod for the camper? In most cases the answer is no, but not for the reasons cited in the replies so far. Ground rods are normally placed upstream of the safety equipment. That would mean the ground should be at the distribution box for the campground if you are on shore power (and there is almost certainly a ground there, by code) or at the generator, if you are making your own power.

Putting an additional ground rod at the camper could create ground loops and cause tripping of ground fault circuit breakers and other issues. The camper should always be grounded by its connection to the power mains.

Many surge suppressors and some power cords have indicators that confirm the power and ground connections are ok, and if they are, that is all you need.

If lightning were to hit your trailer, and you were inside, you would not be shocked because the charge would follow the metal surface of the camper and find its way to ground through the tires, jacks, shore power cord, hitch to the tow vehicle, etc.

The hazard would be if you were sitting or standing outside under the awning when lightning hit. In that case you would be standing on a piece of ground where there was a sudden steep charge gradient and that could be fatal, So if in doubt, go inside and wait out the storm.

In terms of lighting grounding a rod hammered in the ground next to the trailer would not make much difference; you are not at risk as long as you are inside.

The comments about lighting finding its way and being unpredictable are true. I have built and tested equipment to survive this and it is indeed a challenge, one that does not have answers we can easily implement in a campground. But luckily it is not a problem as long as we are inside.