Answers to questions about RV Repair and Maintenance from RV expert Dave Solberg. This column appears Monday through Saturday in the RV Travel and RV Daily Tips newsletters. (Sign up for an email reminder for each new issue if you do not already receive one.) Today Dave discusses multimeters.
What is the best multimeter to have in our tool box? If not by brand name, what functions are mandatory to have, good to have, and would be a nice extra to have? —Dr. Mike
Dear Dr. Mike,
There is a tremendous variety of multimeters available ranging from cheap Harbor Freight models all the way up to the $300-$400 Fluke. The best one for you depends on your level of electrical diagnostic ability. The cheap models will have most of the functions for the average RVer to diagnose 12-volt power at the battery or a 12-volt charge from a converter/inverter. This will also provide testing for 12-volt power at an appliance such as the refrigerator, water pump, and others.
It will also have a setting to test 120-volt power at the campground pedestal with the probes on the 15-amp, 30-amp, and 50-amp outlet. This setting will confirm proper voltage, which should be at least 115 volts and not more than 125 volts, as well as proper wiring. This can be done by testing following the diagram below. Note: The reading between ground and neutral on both 30 and 50 amp should be zero. Insert the red probe in the Hot and the black in the Ground, red in the Neutral and black in the Ground. When checking between Hot and Neutral, you can use either probe. You will get either a + reading or, if the probes are switched, you will get a – voltage reading.
The continuity setting at the lower right can be used to verify an open or closed circuit and testing 12-volt plug in style fuses. Note: Always conduct nondestructive tests, which means no power.
More advanced technical diagnostics
For the advanced technician, you can test ohm resistance as well as DC amp draw. For more information on these and other tests/functions of more advanced technical diagnostics visit electricity expert Mike Sokol’s articles on RVtravel.com.
There are more expensive multimeters such as NAPA, Klein, Southwire, and others that will probably last longer and give a more finite reading in some of the more technical diagnostic issues. However, I have used this model for quite some time and it seems to work fine. Everyone has their own personal model, so I’ll open it up for discussion.
Tools to have in addition to a multimeter
Besides a good multimeter, I would suggest a couple other tools such as a non-contact voltage tester that will do a quick verification of 120-volt power at an appliance or even a cord.
I would also suggest getting a GFCI tester. This one from Klein also shows the voltage.
Read more from Dave here.
Dave Solberg worked at Winnebago for 15 years developing the dealer training program, as marketing manager, and conducting shows. As the owner of Passport Media Creations, Dave has developed several RV dealer training programs, the RV Safety Training program for The Recreation Vehicle Safety and Education Foundation, and the accredited RV Driving Safety program being conducted at rallies and shows around the country. Dave is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club.
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