Lightning Loads
Q: I have attempted to find the answer to the question of lightning strikes to motorhomes or travel trailers. Manufacturers don’t seem to have information to offer. If the RV is metal-skinned, it would seem to be negligible risk. However, if the skin is fiberglass, is there any protection? Finally, if the RV is fiberglass-skinned and there is a metal frame as opposed to a wooden frame, does that offer any protection?
David Drexler
Fitzgerald, Georgia
A: Bill Hendrix and Ray Hobbs, members of Family Motor Coaching’s Technical Advisory Committee and longtime motorhomers, each have information that may be helpful in regard to protecting a motorhome from lightning damage.
Bill Hendrix: “On a 30-amp or 50-amp shore power cord, the round connector links the coach frame/body ground to the power post’s earth ground. This path is designed to prevent an electrical shock from touching an electrical enclosure; however, it will not provide a sufficient conductor in the event of a lightning strike. There are devices that are available to help absorb some of this tremendous energy by putting a gang of metal oxide varistors (MOVs) from the line to a common ground, but I do not know of any surefire, 100 percent safeguard for lightning. If you are in a severe storm, the best protection is to unplug the power cord from the post, but by doing so you may run some risk of personal injury, as you are exposed while you are out there unplugging.”
Ray Hobbs: “We went to Beech Bend Park near Bowling Green, Kentucky, for long holiday weekends for many years and many times a thunderstorm would pass through the area. No big deal. I never regarded being in our motorhome during an electrical rainstorm to pose a greater potential for injury.
“As for lightning surge damage to the motorhome’s AC-powered equipment through the power cord, that threat remains on about the same level as if one is at home and lightning struck at or near the service pole (the one after the service transformer). Over the years at Hobbs Auto & RV Electric, we have repaired wiring and replaced many roof air conditioners, TV sets, and other appliances for motorhome owners who did experience damage.
“For years, our personal motorhome has been equipped with a high-capacity voltage spike surge stop. This is a four-wire (for 50-amp service) device that connects at the power cord connection to the motorhome’s transfer switch. When our coach is plugged in and I’m around the campsite as a storm approaches, I pull the cord until the storm is over. However, if we’re gone, the coach is still protected.
“In recent years, our local electric power utility company has introduced a spike protector for one’s residence called the ‘Meter-Treater.’ This device is about the same diameter as the light meter and about 4 inches deep. The power company installs this unit behind the meter and before the breaker panel. This device really works. In our rural location we used to have lots of lightning strikes that resulted in surge damage to our home electronics.”
Installing Satellite Radio Antenna
Q: I have a 2003 Minnie Winnie type C coach and I would like to add a satellite radio, but I am having a problem figuring out where and how to install the magnetic antenna. Due to the overhang above the cab, there is no suitable place to install it on or near the cab. Can you suggest any way to install it on the roof without cutting holes or screwing it down? Any help you can provide will be greatly appreciated.
Frank Burrow, F370517
St. Helena, California
A: If you can’t use a front fender “” since I believe your hood is fiberglass “” do what I did for my CB antenna. Stop by a metal shop and buy a piece of scrap sheet metal approximately one foot square. Paint it well so it won’t rust. Find a matching flat spot on your roof from which your antenna cable can be routed easily to your radio, and clean that portion of the roof very well. Allow the area to dry. Liberally apply a clear silicone adhesive to the bottom of the plate and affix it to the roof. Next, run a nice bead of silicone around the edge of the plate to keep water from sneaking under the plate. Allow the silicone to dry and attach the magnetic antenna. Enjoy your tunes.
Mismatched Tires
Q: When I purchased my used motorhome, the local Goodyear dealer wanted me to buy eight new tires because the Bridgestones on it were 7 years old. Since I had just spent $3,900 on a front-end rebuild, I didn’t buy all eight but did buy two new 8R 19.5 steering tires (the same size as the Bridgestones that came with the coach). These new tires were Goodyear 647s. Now I’m ready to replace the other six tires (I have a tag axle) and have become aware of the Goodyear 670 tires that have very sun-resistant rubber and can, according to Goodyear officials, be left in the sun with no covers. The fly in the ointment is that 8R 19.5 tires are almost obsolete, and the new 670 tires only come in 225 70R 19.5 size, which is about ½-inch shorter (diameter-wise) than the 647 model tires. The 670s are a bit wider and stiffer than the 647s. The local Goodyear-owned truck repair and tire shop claims I can just move the 647s to the tag axle and put the 670s on the duals and the front axle. I wonder whether this is going to screw up the braking in the rear? The Mor-Ryde tag axle has brake drums, as do the duals. Effectively the tag axle will have a different length lever arm when it comes to stopping as compared to the duals. Any idea what might happen? Nothing? Lower braking effort? Skidding tag wheels?
Mike Rehmus, F389014
Vallejo, California
A: First of all, the Goodyear dealer was correct in strongly suggesting that you replace the 7-year-old tires. Two major motorhome tire manufacturers, Goodyear and Michelin, both recommend that the tires be examined closely by a tire expert at their fifth birthday, probably replaced at six years, and definitely replaced at seven years.
That said, in my opinion, the older Goodyear 647 tires should remain on the front axle and the new 670 tires should be installed on the rear and tag axles. This will give all the tire locations in close proximity with each other the same rolling surfaces. I’m not sure you’d experience the braking problems you’ve mentioned, but it would still be better to keep all the rear tires the same size. Also, make sure the 670 tires leave enough space between each other on the rear duals to allow proper airflow and to ensure that they do not touch each other while rolling. And one last caveat: be certain the weight ratings on the new tires meet or exceed the gross axle weight rating (GAWR) for the tag and rear axles. I also strongly suggest you load your coach in the same manner that you would for an extended trip and have it weighed at a certified scale, such as at a local truck stop, to make sure you’re not overloading the axles.