By Chris Dougherty
Chris Dougherty is a certified RV technician. Here is an article he wrote while he was serving as RVtravel.com’s technical editor.
There are many brands and kinds of multimeters, from inexpensive dollar store specials to Flukes and Extechs. While I’ll refrain from recommending any particular brand or mode, I will make a few recommendations for features.
AC/DC Amp Clamp: Power is measured by volts (pressure) and amps (flow). Since more than half of the electrical system in an RV is DC or Direct Current, having a way to measure DC amp draw is good to have.
Not all amp clamps have DC reading capability, so review the meter you’re considering carefully. The meter should also be able to read AC amps.
DMM, Digital MultiMeter: I prefer a digital scale to an analog one for reasons of accuracy and ease of reading.
Category III minimum: Multimeters are categorized for safety and the maximum loads they can handle. Because troubleshooting AC systems in RVs can sometimes involve high voltage, I recommend a minimum of Cat III.
Fused: Most multimeters are fuse-protected from overloads, but the really cheap ones may not be, and a mistaken overload will cause “magic” smoke to appear from the meter.
Temperature: Some of the nicer meters have a temperature sense function which I use pretty regularly. My meter has both IR (infrared) temp sense and a wired probe. This is especially good for determining if a component may be overheating, or to see if the air conditioner is working properly.
Accessories: Some things to go along with your multimeter include a case for a good meter if it didn’t come with one, alligator clip probe adapters, and spare batteries and fuses.
Editor: For more information or to order, here are multimeters at Amazon.com.