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RVelectricity – Just Ask Mike (J.A.M.): Warning! Lightning season is coming soon; protect your RV

By Mike Sokol
Welcome to my J.A.M. (Just Ask Mike) Session, a weekly column where I answer your basic electrical questions. If you’re a newbie who’s never plugged in a shore power cord (or ask – what’s a shore power cord?), or wonder why your daughter’s hair dryer keeps tripping the circuit breaker, this column is for you. Send your questions to Mike Sokol at mike (at) noshockzone.org with the subject line – JAM. This week I cover what you should do to protect yourself and your RV if there’s an electrical storm coming.


Dear Readers,
This just came from the iRV2.com forums addressed to me. It’s a great reminder of the power of lightning, and why you should disconnect your RV from shore power if there’s an electrical storm coming.

Dear Mike,
So, last week a huge bolt of lightning hit a utility pole about 100 feet from my camper. It completely destroyed the pole (literally cut it in half). Well, apparently it followed the electric or cable wire into my camper. And yes, I had one of those surge protectors plugged into my electric source at the plug, and my camper was plugged into it. Apparently it didn’t help.

Here is what I know

#1) After the lightning strike, several things don’t work. My cable TV distribution went out. The cable running to my camper is still good, and so are my components (TV, modem, etc.). I can stick the cable wire through the window and hook my TV to it and it works. But if I hook the cable up on the side of the camper where you are supposed to, the cable outlets in the camper don’t work. This is so strange to me. I assumed the cable connections inside my camper were just direct wires and a splitter. Is there an electrical component involved in the cable TV outlets in my camper?

#2) My refrigerator stopped working. Obviously, this is the most important problem. What really kills me about this is that my fridge is supposed to work on electric OR on gas. Neither one will work now.

The battery no longer charges

#3) The lights in my camper work but the battery no longer charges. Let me explain. I leave my camper plugged in all the time. However, the overhead lights are all 12 volts. So when things work properly, I suppose there is some kind of battery charger that used the 110 electric to charge the battery and then my lights ran off the battery. So my lights worked several days after the lightning strike but then slowly went dead. I hooked a 12-volt battery charger up overnight and my lights work again but, of course, will go dead again now.

#4) I did have one fuse in my 12-volt fuse box that blew. I replaced it but it didn’t fix any of the above problems. I’ve checked all fuses.

#5) None of my five 110 circuit breakers tripped. I have flipped them off and back on just to be sure.

Why won’t the fridge work?

#6) I don’t know if my fridge worked off my battery the way my lights do. But if so, I don’t understand why it won’t work when I recharge the battery using my battery charger.

#7) My 110-volt plugs work. Everything else seems to work.

My big deal is my fridge, then the fact that my battery won’t stay charged to run my overhead lights, then there are my cable outlets.

Does anyone have any idea what might be going on? I seriously doubt I can fix it, but perhaps there is a fuse I don’t know about or a reset or something???? I have a 23-foot Highland Ridge trailer. It is a 2019 model.

Any help or insight would be appreciated Sooooo much! —an iRV2.com reader

Dear iRV2er,

Basically, everything electrical in your RV has probably been damaged, and even the few things that are still working will likely fail soon. Now is the time to test EVERYTHING, and replace as much of it as possible. Lightning is a cruel master, and it goes wherever it wants to go, damaging everything in its path.

I’ll be writing a full article about this next week. But off the cuff, I do know that a typical cloud-to-earth lightning strike has around 1 billion joules of energy. This is 1 billion watts of power for 1 second, or 277 kWh per lightning strike. That’s enough energy to power your entire house for weeks, in just a single lightning strike lasting microseconds.

How powerful is a lightning strike?

Considering that an EMS Surge Protector has maybe 3,600 joules of MOV protection, it’s obvious that 1,000,000,000 joules of energy from a direct hit on your shore power wiring during an electrical storm will destroy any Surge Protector, and probably everything electrical in the RV. And don’t forget the over-pressure damage to the tires and welded wheel bearing from the lightning strike passing through the tires.

Protect your RV during an electrical storm

The best way to protect your RV from lightning damage is to unplug from shore power during an electrical storm and run from batteries.

I did a study last year which suggests the possibility of insulating pads under the jacks could possibly reduce lightning damage from a nearby ground strike that creates large differential voltages across the earth.

Read Part #1 HERE

Read Part#2 HERE

OK, everyone. Remember that electricity is a useful and powerful force, so we all need to pay attention to safety precautions while using it.

Let’s play safe out there….

Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.
Join Mike’s popular and informative Facebook group.
And you don’t want to miss Mike’s webcasts on his YouTube channel.

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Paul S Goldberg30 amp
5 months ago

Our coach was at a 50 amp connection while we were away. When we came back there had been a serious storm with lightning in the area. The 50 breaker was tripped. One board in our Dometic refrigerator was blown. The 30 amp fuse from my solar panels at the batteries was blown along with the wires on either side of the fuse being blackened and burned through. This happened 4 years ago and I have not yet seen any other sign of degradation of electronics in the coach. The solar controller continues to work! As you say lightning will go where it chooses and destroy whatever it touches. I am grateful to still have my coach.

chris
5 months ago

Lightning nearby? UNPLUG!!

Bill
5 months ago

Mike, wouldn’t that suggest electrical wiring would have something like heat melted wire insulation and the copper wire would have meld as well in places?

Irv
5 months ago

Great photo of a lightening strike. Where’s the source of the photo?

Mike Sokol
5 months ago
Reply to  Irv

The top picture is from a government site about lightning safety, but I can’t remember the name of it off the top of my head. And yes, it’s a real picture, not a mock up. Pretty terrifying, isn’t it?

The multi-colored photo of the lighting hitting the tree is an artist’s recreation of two different strikes, with coloration added to show how the lighting strike branches out over the surface of the earth before it’s completely grounded. Yet another scary picture.

Diane Fox
5 months ago

What do you recommend putting under the metal jacks and wouldn’t there need to be something similar under the tongue jack? Would the rubber knee pads made for gardeners to kneel on do the trick. Thanks so much for all your informative and, I suspect, life-saving articles!

Mike Sokol
5 months ago
Reply to  Diane Fox

Basically anything that non-conductive and at least an inch thick should work. So kneepads could be good, and the SnapPads I mention in the articles would work under the jacks, but you still need something under the tongue jack. I have a sand foot on mine which is maybe 4″ by 6″ square, so perhaps I need a chunk of plastic around 6″ x 6″ to complete insulation. Again, nothing will save your RV electrical system from a direct strike, but jack pad insulation could save you from those crazy ground currents.

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