Lightning

Topic: Lightning (Read 1296 times) previous topic - next topic

Lightning

February 04, 2012, 08:33:47 pm

OK, how about lightning. In a house, we're advised not to shower when there is lightning but how about in the motorhome? I'm thinking we don't have any water pipes going to ground so standing in water in the shower shouldn't be any more dangerous than just being in the coach. Agree?
jor

Re: Lightning

Reply #1 – February 04, 2012, 09:22:20 pm

True. Do you really want to be in the shower when lightning strikes within a mile of you? The noise can be quite loud. You may have a new skylight over your shower.

Re: Lightning

Reply #2 – February 04, 2012, 09:49:20 pm

Don't know about the shower issue. I think I read somewhere that a conservative action in case of a lightning storm would be to disconnect shore power and cable. Seems like a good idea to me.

Re: Lightning

Reply #3 – February 04, 2012, 11:20:51 pm

Just throw on a little extra baby powder. You'll be fine.

Re: Lightning

Reply #4 – February 05, 2012, 09:11:08 am

I'd personally am inclined not to be near water or wet if lightning is in the vicinity. Makes you a much better conductor than when dry. They say your chances of getting hit by lightning are very slim, but in my lifetime lightning has struck within 20 feet of me three times. Maybe it's my aura...

I'd definitely disconnect shore power and cable. I would also kill power to everything not needed and shut the down the gennie if running. Better safe than sorry.

Lightning hit in my yard once, and the EMP travelled up a coax cable a lazy installer ran outside the house from the 1st floor to the 2nd (about 30 feet from cable to lightning strike). It fried everything connected to cable - all the TVs, modem, router, and two computers hardwired to the router. The computer power supply cases were blue from the heat generated. The lightning hit a tree about 15 feet off the ground and went down into the ground, stripping a big swatch of bark off the tree along the way. It never touched the cable, yet caused a great deal of damage.

I'd rather err on the side of caution where lightning is concerned.

Steve

Re: Lightning

Reply #5 – February 05, 2012, 09:22:28 am

Lighting is very unpredictable. When I was very young we had lighting come in through the kitchen window screen, pass through the kitchen, and go out through the back screen door. It did nothing but melt the medal screens, and then stuck the black cherry tree in the back yard. It passed up a apple tree. Well, it did raise some hair while passing through the kitchen as we were sitting there eating supper. The family never talked about that very much.

Re: Lightning

Reply #6 – February 05, 2012, 04:58:30 pm

I didn't go out and unplug the mpg the other day when there were a few rumbles of thunder, but if severe thunderstorms are predicted I will. It does have a surge protector in the line.

Re: Lightning

Reply #7 – February 05, 2012, 06:01:42 pm

About ten years ago, I was mountain biking north of Atlanta. A while after I started, a light rain came on. I was sweating more than the rain, so I kept going up the hill. When I got at about to the maximum point from shelter, the thunder and heavy rain started in the distance. I turned around and headed downhill, but the storm caught up with me. I figured that soaking wet, on a metal bike, in the clearing of the trail was not the best place to be, so I dropped the bike and crouched in a small ravine.

I sat on my heels in what became six inches of moving water with the lightning around me, and my hair on my arms standing up. You know when you hear the electrical snap a second or so before you hear the deafening thunder? I heard that about twenty times that day.

I don't know if that makes me blessed or overdue...

Re: Lightning

Reply #8 – February 05, 2012, 06:26:46 pm

I bet your the one that would be lucky buying that old coach for $5 K, your young and daring.
Good luck.

Re: Lightning

Reply #9 – February 05, 2012, 08:26:14 pm

About 3 years ago lightning hit an oak tree about 3 feet from the coach, and where shore power plug is. It came in on the power cord and destroyed the transfer switch (melted all of the insides). Foturnately that was the only damage. Soooo when thunder storms are in the area the coach is unplugged, at least when it's parked at the house.

Re: Lightning

Reply #10 – February 05, 2012, 11:24:47 pm

I usually put the lightning rod ( TV antenna) down and unplug the power cord if it sounds like it is heading our way.

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Reply #11 – February 06, 2012, 03:54:21 pm

I know it sounds screwy but antennas should stay up. This bleeds off ions and makes a cone of protection below. When fishing offshore and a squall blows up outrigger poles are raised. This is how lightning rods work assuming vehicle is grounded otherwise all bets are off.

Re: Lightning

Reply #12 – February 06, 2012, 04:07:30 pm

Quote from: Chuck Pearson – February 06, 2012, 03:54:21 pm

I know it sounds screwy but antennas should stay up. This bleeds off ions and makes a cone of protection below. When fishing offshore and a squall blows up outrigger poles are raised. This is how lightning rods work assuming vehicle is grounded otherwise all bets are off.

Boy, that must make our sailboat REALLY safe, since we have a 53' aluminum lightening rod! Have been through a terrible lightening storm about 70 miles west of Tampa in the Gulf of Mexico, but were not struck.

Brett

Re: Lightning

Reply #13 – February 06, 2012, 05:18:58 pm

Quote from: Chuck Pearson – February 06, 2012, 03:54:21 pm

I know it sounds screwy but antennas should stay up. This bleeds off ions and makes a cone of protection below. When fishing offshore and a squall blows up outrigger poles are raised. This is how lightning rods work assuming vehicle is grounded otherwise all bets are off.

When a coach is connected to shore power, there is generally only a single ground point via a #6 wire. If one chooses to disconnect shore power to avoid introduction of dangerous voltages via AC mains, the coach is not likely to grounded at all.

What do you recommend regarding disconnecting shore power and deployment of antennas?

I did see one sailboat that had been struck by lightning. It was a Flying Scot (19' day sailor) on a trailer near Galveston Bay. The boats at the club were stored on trailers with masts erect. One could trace the path of electricity from the lightning strike. There were burn marks from mast to boom, boom to boom crutch (metal), boom crutch to trailer frame, and wheel to ground. The lightning blew a 3" hole in the fiberglass hull where it jumped from the base of the boom crutch to the trailer. I expect at least one of the wheel bearings was toasted as well.

Re: Lightning

Reply #14 – February 06, 2012, 07:48:39 pm

Does anyone know of a motor home taking a direct hit? If you knew severe weather was headed you way and you were going to unplug would it help if you draped a chain over the hitch to the ground?

Re: Lightning

Reply #15 – February 06, 2012, 07:52:29 pm

A friend had his U295 stored in a barn at his house. A lightening strike screwed up s bunch of electronics in the house, it hit a tree traveled thru the root system and entered the house via a waterpipe.
Only months later did he determine that the Genny, reefer, AC and some other electronics in the coach were also inoperative.
Gary B

Re: Lightning

Reply #16 – February 06, 2012, 08:30:04 pm

Have been avoiding this subject, now I guess I should say something about our experience with our home and 150' Ham Radio tower, after many $5 - $10 K lightening strikes, only one was turned into the insurance. We decided after many attempts to solve the issue once and for ever.
Talked with the Poly Phaser engineers, They recommended, a 3" copper strap around the house, buried, every 15' drive a 8' copper clad ground rod, cad welded, stayed 15' from foundation, then branch down to the 150' tower. This took 500' of copper strap, then added another 500' 1.5" strap in radials with the ground rods under the tower, all cad welded and buried about 6". Then added a 200 amp choke type suppressor at incoming meter cab. The single ground was to the ground/neutral at meter cab.
That all happened about 20 years ago, not a single issue since.
Cost was about $4,500.00 that included the HD Milwaukee Electric jack hammer with ground rod driver. Yes, installed 96 8' copper clad rods.
The solution was simple, just mimic the AT&T tower site grounding system. They never seem to have an issue, so that was part of the discussion with Poly Phaser.

Good grounding is the only answer, other wise you are guessing. A single ground rod is not being grounded.

Cheers

Re: Lightning

Reply #17 – February 06, 2012, 10:10:39 pm

My option is disconnect shore power at RV, along with all other cables (TV), water, & sewer line. Make sure antenna is lowered. Sit down and watch the show. I would stay out of the shower, just does not seem so safe.

Re: Lightning

Reply #18 – February 07, 2012, 01:41:04 am

For about 10 years in Miami, I owned a 36' fiberglass sailboat. The mast was stepped on the top of the cabin and supported by a bulkhead and a teakwood column to transmit the load to the keel. The lead ballast was inside the fiberglass hull. None of the bronze thru-hulls were bonded with ground straps. The mast and none of the chain plates for the rigging were grounded. I didn't think this was very good, so I had a bronze plate or shoe made to fit the bottom of the flat keel. A 1/2" bronze rod threaded on the end long enough to penetrate the keel and ballast into the bilge was welded to the shoe. From there it was connected via a heavy copper cable to the mast by a copper/aluminum connector. A thunderstorm passed by while the boat was in a haulout slip overnight waiting to be lifted out of the water when a bolt of lightning hit the mast. No one was onboard at the time. The vhf radio antenna on the mast basically disappeared, however the radio still worked with a new antenna. The batteries went dead in a couple of days and had to be replaced. The alternator had to be replaced. Apparently most of the lightning did not like the shoe as it did not seem to be touched. A bilge pump discharge hose was blown off a plastic thru-hull located above the waterline. All the below water bronze thru-hulls had lightning stroke like lines etched into the copper bottom paint around them out for several inches. At one spot lightning penetrated the hull below the waterline creating a small hole and fracturing the fiberglass for about an inch or so in diameter. The hole was so small that almost no water came in. The main course of the lightning appeared to be down a side stay to a chain plate then to a copper water pipe aft to the galley locker where it put some burn marks on pots, pans, forks, spoons, and knives. Two or three locker doors were opened. From there it somehow traveled about 7' to a bronze engine exhaust thru-hull on the transom and jumped over to the concrete slip. A chunk of concrete was knocked out of the slip wall exposing a piece of rebar. It seemed to prefer that route to ground rather than the salt water. A person about 50 feet away working under a boat said he received a shock. So lightning does whatever it wants to do.

My parents house was next to a house that had lightning rods. That house was struck 3 or 4 times in the 18 years that I lived there growing up, but it received no damage. Sure scared the people who lived there though. The 2 houses on either side did not have lightning rods and were never struck. Maybe I should have left the boat the way it was built; who knows.

Re: Lightning

Reply #19 – February 07, 2012, 10:08:51 am

What ever happened to the theory that the rubber tires provide insulation to ground so that if the power cord and hose are disconnected, there is very little chance of lightening striking your motor home. The surface water on tires just doesn't have enough mass to be a good pathway to ground for lightening.

I have always unplugged when I knew a storm was coming. Am I wasting my time as well as getting my balding head wet? I have however been remiss about leaving the power cord outside laying on the ground. I guess I should roll it up back in the coach.

Re: Lightning

Reply #20 – February 07, 2012, 10:26:54 am

Quote from: Kent Speers – February 07, 2012, 10:08:51 am

What ever happened to the theory that the rubber tires provide insulation to ground so that if the power cord and hose are disconnected, there is very little chance of lightening striking your motor home. The surface water on tires just doesn't have enough mass to be a good pathway to ground for lightening.

Even today, 250 years after Benjamin Franklin demonstrated that lightning was electricity, lightning is not well understood. The latest theory is that it's the metal body on an automobile that protects you from lightning (if you are inside) not the fact that it is not well grounded. The potential energy in a lightning strike really has no problem jumping the few inches from your vehicle's metal hubs to the ground (after all, it probably just jumped a couple of hundred feet from a cloud).

Of course, for FT owners, this comes as unwelcome news since the Unihome and Unicoach models do not have a handy-dandy metallic frame (or body work) to provide such shielding.

Despite this theory, I think that disconnecting the cable (from the coach... and moving it away) is a good idea. Mainly because.... it can't hurt. A 50--amp electrical connection does have a path directly to ground and it's got to be a lower resistance than the air-gap between the coach and the earth beneath it.

Craig

Re: Lightning

Reply #21 – February 07, 2012, 10:31:34 am

Re: Lightning

Reply #22 – February 07, 2012, 10:40:54 am

Quote from: Paul Smith – February 07, 2012, 10:31:34 am

A Lazy Daze has an all metal exterior, but that did not prevent lightning from damaging its electrical components.

Since devices like radios, tv sets, glass-dash, and other components are electrically bonded to the chassis as well as the metal skin of the exterior they wouldn't necessarily be protected from a lightning strike to the vehicle. Only the lightning knows where it wants to go. What the exterior does is give the lightning a path down and around a person that does not include the person.

Which probably means that taking a shower in an RV during an electrical storm is a bad idea; even if you do have a hot date for later.

Craig

Re: Lightning

Reply #23 – February 07, 2012, 12:43:24 pm

Kent not much rubber between steel belted tires and earth. Tires are a better conductor now then years ago when they had no steel.

Re: Lightning

Reply #24 – February 07, 2012, 01:16:47 pm

Actually there is a misconception that lightning "strikes" things. IE: Comes down out of the clouds and nails something. Lightning is a difference in the negative charge in the cloud and a positive charge in the ground. As the negative charge builds in the lower part of the cloud it sends a "Step Leader" down towards the ground. At some point as it approaches the ground a second leader goes up towards it. When they connect there is a powerful return stroke up into the cloud and the voltage differential is equalized somewhat. The positive charge in the ground is what causes one's hair to stand on end when lightning is about to strike. Remember that electrons flow from negative to positive. In electron flow theory that's how they actually go not positive to negative.

So this means that you either want to be a lousy conductor or a really good on. The first to prevent the flow of electrons upward and the latter to direct them into the ground without harming anything (lightning protection).

All that being said lightning seems to not follow the rules sometimes and does weird things. So all the above is really a generalization.

I have seen a several of sailboats that were struck by lightning. One was hit at the end of the Mackinaw race. It struck the mast destroyed all the electronics and exited at the waterline causing a perforation all around. Looked like a stamp. On another the lightning exited through the thru-hulls blowing one completely off the hull. A third started the engine on fire. All vessels had a grounding system.

At a city that I worked for the Police Dept emergency antenna was struck causing three out of four 911 consuls to be damaged and lightning to jump from the mast through the metal window frame of the Chief's office and destroy his typewriter.

You can see that it's a slow day around here

Keith

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