Part 1 of my study on RV grounding in a lightning storm
Staying safe in a lightning storm: Part 1
Can insulating pads under your leveling jacks help reduce damage to your RV’s electrical system from a nearby lightning ground strike?
I’m beginning to study this concept just in time for lightning season. For many years I made the claim that insulating pads under your RV jack stands would do nothing to protect your RV from electrical damage in the event of a direct lightning strike. And I believe that is still true, having performed a recent insurance inspection for a $500,000 coach that suffered a direct lightning strike on its roof.
However, for every direct strike, there are probably hundreds of smaller lightning ground strikes in the area that energizes the campground wiring. And it’s possible that insulating jack pads could prevent something I’m now referring to as a whiplash effect through the ground and where a DC pulse lightning current damages more of your electrical system due to secondarily grounding your RV, rather than insulating it from the ground. Join me as I begin to study this phenomenon and review technical papers on how insulating your leveling jacks might reduce electrical damage to your RV.
Here’s a screenshot of the video that got me interested in the effect, and why I contacted SnapPad about the possibility that their jack pads may provide extra protection for your RV’s electronics from nearby lightning ground hits. Note that when lightning hits the earth it doesn’t go straight down. Instead it takes multiple paths across the earth in varying depths in an attempt to find true earth ground.
Do jack stands ground your RV?
Now let’s imagine that your RV is sitting on its metal jack stands on the wet ground, so it has a fairly good connection there. These jack pads are acting like a secondary grounding rod (albeit a rather small one). Now instead of the lightning electrical pulse coming into your RV from the pedestal, what if the DC pulse comes across the earth, is picked up by your grounded jack stands, and then tries to leave your RV via your shore power ground connection in the pedestal. I can only imagine that will wreak havoc with all of your expensive RV electronics.
What about insulating pads?
Now as I’ve noted many times before, nothing can stand in the way of a direct lightning hit to your RV, and only a metal-skin RV can shield the occupants (you) from the lightning going directly through your RV. But I do believe that insulating pads can reduce and possibly eliminate damage to your RV electronics if lightning hits nearby and you’re still plugged into shore power.
This is just a preliminary announcement of a study that’s now being funded by SnapPad. They’ve commissioned me to create a report on what I find, good or bad. So watch for more updates to my study as we get into lightning season soon and I find more papers and studies on this effect. Now if only I could build a 30-foot-tall Tesla coil in the back yard to make a real lightning simulator. And then I have to find someone to loan me their RV. We shall see….
Let’s stay heart safe out there… Mike
We can air level our coach which means the jacks are not down, but using the airbags to level. With 6 tires on the only, would that provide any protection from a ground strike entering our coach?
Where is Nicola Tesla when we need him?
What about other substances under the jacks, such as wood or one of the various plastic blocks, such as lynx leveling blocks, home on wheels blocks etc.?
When you build your giant Tesla coil, let us know because I’m sure we’ll all want to come and watch! 🙂 This will be a great study and I’m looking forward to it. Every year in Honolulu they have the Lantern Festival where they build a huge stage that sits half on the beach and half in the water. The first time I went there to teach an electrical safety class for the stagehands, several people told me the portable power generators that feed the stage are “grounded” by throwing a grounding rod in the ocean and they asked if that was the right thing to do. After thinking about it for while I theorized that it more likely could bring energy from a lightning strike in the ocean back to the generator and the stage through the grounding conductor. Your screen capture seems to reinforce that idea.
Mike – We were hit by lightning on July 1st, 2018, while staying at John Gurney Park in Hart, Michigan. The strike caused about $7K in damage to our Tundra. I also had to replace the power supply module and the shoreline power cord plug in our 2008 Jayco BH19 trailer. The lightning hit the tall tree next to us, passing into the Tundra parked about 2 feet beside the tree. The lightning then passed to the trailer parked a couple of feet beside the truck and out of the power supply cord into the campground’s pedestal, disabling it. It also passed out of the truck from the bottom of the tailpipe and the towing hitch, blowing a 4-inch diameter hole into the concrete pad the trailer was sitting on. We were sleeping at the time, but the vehicles were not insulated in any way other than their respective tires. We had to fight State Farm to cover this, as they didn’t see any immediate evidence of a strike. Both vehicles are still in service today. I have pictures and additional information if it would be helpful to you. – Jim
Just something to maybe put into play with your study. I’ve been a big believer in always having pads down under our RV jacks for many years – after wooden blocks we went to rubber patio pavers and finally SnapPads – plus I like to unplug if there’s dangerous lightning in the area if I catch it in time. But I grew up with other lighting experiences from “the school of hard knocks” that play a part in why I take precautions, including seeing electrical arc fly out about 5 inches into our house when lightning must have struck in the nearby area and induced into our farm 3-phase power lines. I’ve never lived or owned a house since where I didn’t install an old-school-type sand-filled 600v spark gap lighting arrester (I even used to do that in any of my RV’s before RV-type and eventually EMS-type surge protectors became popular, of which I was an early adopter), plus all our houses were outfitted with whole-house surge protectors for the under-600v surges (which actually caused a problem and started smoking one day (because of the way some farm 3-phase is implemented of two 120v + one 240V legs sometimes leaves around 50 volts active from the power pole transformers if one leg goes down), but we luckily caught it in time before it erupted into a house fire). My point with that long explanations is that there are reasons I’ve learned to take hopefully never needed extra precautions.
So, your study was reminding me of something I learned from local shops during the big-dish satellite days. It used to be popular in some installations to mount the large C-band dishes maybe 100-300 feet away from the house, sometimes for aesthetics and/or sometimes for open-sky-arc clearance (just as a refresher, C-band usually involved using a movable dish from east to west on a southern arc to switch to desired satellites and obstructions such as trees blocked the signals). Well, a pattern of damage from storms began to emerge in those early days. The electronics even at that time were sensitive to static and surge damage, and most of the receivers had three-prong electrical cords as required, and it was standard practice to ground each installation at the dish. It started to be noticed that the installations in newer houses with proper grounded electrical receptacles were getting damaged in many electrical storms while the receivers in older homes with only two slot non-grounded receptacles would solder on through anything short of a direct lightning strike. What was the difference? The older homes it was common practice for the home owners to break or snip off the ground pin (I never recommend that) or to use a two-prong adapter plug without hooking up the ground screw (the receivers were still grounded through the shielded cable to the dish ground). The reason for the reoccurring damage was because, if we take a theoretical example of a close lightning strike 3 miles away, the ground potential at the house might be 150,000-volts potential, while the dish being 100-300 feet away might be at 100,000-volts potential. If you were physically standing in either spot, you would never feel a thing, but the electronics being much more sensitive might feel the 50,000-volt difference which in many cases was enough to blow out the IC chips on their receiver circuit boards.
If you apply the same analogy to RV’s, they should be already grounded through their power cords (if plugged in) to the campground power system central ground, but just like the distant satellite dish, grounded RV jacks could set up an alternate ground system with the possibility of a similar difference in ground potential voltage just like in my satellite example, between the campground ground (for example using the same numbers of 150,000 volts potential) and the local RV jacks (at 100,000 volts potential) having a similar to my satellite example 50,000 volts difference in voltage potential, which is enough to damage most modern RV electronics.
Of course, all bets are off in the case of a direct or close enough lightning strike. Would a “grounded through the jacks” RV drain some nearby lighting static away into the ground and prevent or lessen damage – or would it make that grounded RV an easier target magnet for lightning to hit (even among the trees)? I’m not sure that specific situation occurs frequently enough to even warrant sturdy – but that satellite example of ground voltage differences was frequent at one time and might be similar to setting up the potential difference between the campground electrical system central grounding and grounded RV jacks some distance away from that central ground.
I found today’s article and readers comments interesting. I have no experience with lightening events in my life. It seems, whether insulating a lot or a little has various benefits or consequences based on the high voltage electrical charge that can come from any direction, at any possible potential, air, ground, wire, or water. It seems possible that adding prevention for one possible event may reduce protection for another kind of high voltage event. Basically, it seems to me we are likely damned if we do and damned if we do not.