AC Voltage Problem
Dear RV Doctor:
I have a 2010 Thor Motor Coach Windsport 32A. I hooked it up to shore power in the driveway for about a week. All 120-volt electricity was off. I checked the shore cord and everything is okay. I tested the outlets, and the tester indicated that the ground and hot were reversed on all the outlets. It’s always worked fine in the past. Any ideas?
Robert Reidlinger
Via e-mail
First, unplug your motorhome until you can determine the exact cause of the fault! Hot/ground reversal is potentially dangerous! My inquisitive nature prompts me to ask how you “checked” the shore cord and how you determined it was okay. We’ll get to that in a minute, however.
Chances are, the problem is either at the power source or at an extension cord or pigtail adapter. If you are absolutely sure no one has added or replaced any 120-volt-AC component anywhere in or on the motorhome, we can probably eliminate the RV itself as the cause — for now. If you have access to a digital multimeter (DMM) and can safely measure outlets, I’d first check the source receptacle for proper polarity and the correct voltage. I wouldn’t rely solely on one of those inexpensive, three-LED plug-in circuit analyzers. Always use a decent DMM. Measure between the hot and neutral positions on the source receptacle in your house or garage. The reading should be 120 volts AC, plus or minus 5 percent. Next, measure between the hot and ground connections on that same source receptacle. Again, the reading should be 120 volts AC, plus or minus 5 percent. The reading should show zero or near zero volts between the neutral and ground connections.
Next, measure for continuity through your grounded extension cord, if you’re using one. And be sure it is indeed a grounded cord, fully rated to carry the load of the RV. Be sure the extension cord carries the same rating as the shoreline cord on the coach. Be very sure you have continuity through each of the three conductors, from one end to the other. Brighten all the exposed prongs using #0000 steel wool or emery cloth. If you’re using a pigtail adapter to reduce the 30-amp shoreline cord to a 20-amp or perhaps a 15-amp source receptacle (not recommended, by the way), be sure it, too, has clean prongs and proper continuity through all three conductors.
I also would invest in a noncontact voltage tester to verify the polarity of the voltage at the source receptacle. This is the only viable method to determine that the source receptacle is wired properly for a three-wire connection.
I’m guessing you’ll find the fault within one of the tasks mentioned above. But if not, next turn your attention to the RV itself. Has anyone modified anything inside the RV recently? Installed anything? Screws and staples can penetrate the insulation of electrical conductors, so don’t limit your thoughts simply to electrical components in or on the RV. One reader experienced electrical issues after simply installing a roof rack. Yep, one mounting screw pierced a piece of Romex wiring in the roof.
RV electricity expert Mike Sokol created a test to ensure that a proper safety ground exists throughout the motorhome:
This is a simple and cheap method to test your RV’s ground system for current-carrying ability, which is the only way to know that your ground system is intact and can protect you from harm. Note that I’ve included a standard 12-volt #1156 bulb, which draws about 2 amps and provides the current limiting, and, of course, you’re working with only 12 volts DC, so that’s safe as well. Also note that your motorhome is disconnected from shore power while doing this test.
“First, connect the test light from the positive terminal of your RV’s house battery to the ground pin on your shore power cord. The bulb should light up brightly. If not, then you have an open ground connection from the frame of your RV to the shore power cord’s ground pin. That’s a big no-no, which must be corrected immediately. If the bulb lights up dimly or blinks as you move your shore power cord around, then you have a loose ground connection somewhere. Again, that’s a big no-no, which must be corrected. Next, if you have a steady-bright test light, you need to confirm the voltages. So, using a DMM set to DC volts, measure directly across the battery terminals, which we’ll assume is 12.6 volts. Then, measure across the two test clips on the light bulb, and you should find very close to the same voltage, but not less than 12.5 volts in this case. If you measure more than 1/10 of a volt difference, then you have a corroded ground connection somewhere in the motorhome.
“You should repeat this test, adding onto your shore power cord any extension cords, pigtails, or dog-bone adapters you may use. If the test bulb blinks or goes dim, then you have a failure in the rest of your power hookup cables. Those broken cables and adapters must be removed from service and replaced or repaired. Finally, do the test again with the test clips between the battery positive terminal and the chassis of your RV. This assures that you have a solid contact between the battery ground and the RV frame, which sometimes corrodes or is painted over during the build.”
Again, do not plug the coach in until you can determine where the cause originated and that it has been rectified. Never compromise the safety factor!
Winterizing Tip
Dear RV Doctor:
I have winterized my RV before, but this year I am having some difficulty. I put the antifreeze in the holding tank and I turned the pump on, but I’m thinking there must be air in the line, because when I turn the faucets on, nothing comes out. I sure would appreciate a tip.
Sam Oliverio
Via E-Mail
I’m assuming you meant to say you put RV antifreeze in the fresh water tank, and that you didn’t mean one of the waste holding tanks, right? Did you place the water heater in bypass mode? If not, with the fresh water system void of water while you are trying to distribute the RV antifreeze, the pump will first attempt to fill the heater before it can satisfy filling the rest of the fresh-water system. The bypass kit, which is attached at the rear of the water heater, basically eliminates the heater from the system by tying the hot and cold lines together just ahead of the inlet to the heater. Also, be sure the low-point drain valves are closed. Otherwise, you’ll be pumping the antifreeze directly out of the system and onto the ground. You also may have some air in the system, as you indicated, but eventually the antifreeze should be visible at the faucets. Today’s RV water pumps are self-priming, so perhaps it just may take awhile to eliminate the air in the tubing.
Let Me Level With You
Dear RV Doctor:
We have a 2004 Winnebago Sightseer with Kwikee hydraulic leveling jacks. I have seen other motorhome drivers lift either their front or rear wheels off the ground to level the coach. Is this safe to do for a weekend stay, or should you never take the wheels off the ground in case of a failure in the system?
Bob
Via e-mail
In my opinion, it’s never a good idea to lift all tires on the same axle free of the ground on any RV. In severe cases, I have seen setups where one tire is lifted off the ground slightly, but that could still be troublesome and certainly is not recommended. If the ground is that off-level, I’d suggest moving to a different site. Considering the safety issue and the design of most parking brake systems, including air brakes, never raise the drive-axle tires clear of the ground. This is especially dangerous if parked on a sloped surface. In fact, I would recommend that raising a drive-axle tire should be limited to less than 50 percent of the spring travel. Since all parking brakes activate the drive-axle brake assemblies, keep those sneakers on the ground!