When a 120-volt component is not working, I have found that oftentimes it is not the component that’s the problem, but an open circuit somewhere downstream. Tracking down the “gremlin” can be difficult without the proper tool. The non-contact voltage tester has been one of my go-to tools for not only RV troubleshooting, but residential, as well.
There are a variety of types of non-contact voltage testers, with a very wide price range; however, I like this one from Amazon.
The non-contact voltage (NCV) tester will sense 120-volt power running through a wire, outlet or switch with a sensing probe in the tip. It is the safest and easiest way to detect power without physically touching a “hot” or live wire.
Several models of non-contact voltage testers available
Several models are available with the cheapest having just one setting or voltage range. It will show voltage in a general area, but not as specific as I like. For example, if I want to test an outlet for power coming in and going out, the cheap tester will show voltage all around the outlet, even if the power is not going out to the other ganged outlets.
Having a sensitivity setting or optional ranges, I can pinpoint the exact feed and it will not flash just anywhere near the outlet. When it is close to an outlet or power cord, the voltage detector will emit different levels of alarm sounds and signal indicator lights to indicate the presence and strength of voltage.
You can also use the NCV tester to trace a wire that has an open connection, such as a broken or frayed wire.
The NCV tester can help isolate an issue
This tool is great for verifying power coming to a component, which will isolate the failure to that component. Or it will verify there is no power. That means the component might be good and there is an issue with the wire, connection downstream or at the circuit breaker.
Keep in mind this only detects the presence of power and not specific voltage. It also has a small light to help illuminate dark areas. The NCV tester detects AC power and will not work on 12-volt DC.
Using a non-contact voltage tester to test “hot skin”
A condition known as “hot skin” can occur on your RV if a ground wire becomes loose or broken in your electrical connection. The voltage can rise to an unsafe level. Normally there is a small amount of voltage, below 5 volts, of the earth. The ground wire’s job in your shoreline cord is to keep it below that.
Anything above 30 volts is dangerous. Touching any metal component on your RV could cause a slight tingle or even worse on higher voltage.
To conduct the test, plug your unit into the campground source and use the NCV tester on any metal component such as the tongue of a trailer or entrance steps. Keep in mind that even if you have a fiberglass skin construction there is metal in the chassis, outriggers, door frame, and wall framework.
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RVDT2795
These are useful tools for checking for power, however, you should never rely on one to ‘prove’ the power is off. They generally require 30 to 40 volts to activate the power on. Always use a quality multi-meter to prove the power is off before working on electrical items.
Exactly. There may not be enough power to run the appliance due to bad connection, but the line is still live.
The best way to check for power at an outlet is to use a plug in tester with a built in voltmeter.
Decided to buy one to speed tracing. But agree with Terry Colquhoun that before working, verify the power is off at the breaker and use a contact voltage tool to verify the power is off on that circuit.
Thank you for the suggestiin, Dave! Still another tool that I acquired at your behest. Have a great day, safe travels, and grand 2026!