Monday, September 26, 2022


RV Electricity – Is this non-contact voltage tester on?


Dear Mike,
I just finished reading your book “RV Electrical Safety” twice.  You have demystified things I’ve only guessed at for years.  I now feel more comfortable working around the pedestal and connecting my RV to shore power at campsites.  Thanks for all that you do to help keep us RVers safe around electricity.

I have a 30-amp outlet on the side of my house and I decided to check it with the techniques you described in the book.  There are two outlets in the box, the 30 amp and a 20 amp. I checked both with the non-contact tester and it showed no hot contacts. I assumed the breaker had tripped.

I then plugged in a 3-light tester and it showed the 20-amp outlet was correctly wired. Is this tester self-powered or does it need power from the contacts to operate? If the latter, I don’t understand the reading from the non-contact tester. My NCVT is a Fluke VoltAlert 1AC-A II. I just got it for Christmas and used it inside the house to check some wall outlets and it worked fine (and so did the outlets). I’m pretty sure it was turned on, but I’ll go test the RV outlets again and check the circuit breaker. —Bruce

Dear Bruce,
Yes, the 3-light tester gets its power from the outlet itself. But you do need to verify that your Non-Contact Voltage Tester is working by first trying it on a known powered outlet. Since you confirmed the outlet has voltage with the 3-light tester, I’m guessing that something is wrong with your NCVT test procedure. Could be that it’s non-operational, the batteries are dead, it’s not turned on, or you’re using it improperly.

When working with any type of electrical test gear, be it a voltmeter or an NCVT, you first need to confirm that it’s turned on and operational by checking it on a known good power source before using it to test an unknown outlet. And any NCVT can only confirm the presence of voltage, not the absence of voltage. That is, if it does beep at you, then it’s a sure indicator that the NCVT is detecting some kind of voltage. But if it doesn’t beep at you, then it’s possible that the NCVT batteries are dead, it might be turned off, or you might simply be using an improper testing technique.

An NCVT is not the gold-standard for voltage testing – it’s just a really quick test method you can use anytime. But if anything looks the least bit off about a campground pedestal or electrical outlet in your home, then you need to get out a real voltmeter and do a deeper level test.

Let’s play safe out there….



Mike Sokol is an electrical and professional sound expert with 40 years in the industry. Visit for more electrical safety tips. His excellent book RV Electrical Safety is available at For more info on Mike’s qualifications as an electrical expert, click here.




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4 years ago

The NCVT lights ups only in positive prong with DC or generator powering my motorhome. However, when plugged into shore power the negative and ground will also light up NCVT. Should I be concerned?

Tim Burke
4 years ago

Concerning the 30 amp receptacle, the tip of the non contact tester MAY not come close enough to the contacts in the receptacle to get a reading.
On physically larger receptacles(30,40,60 amp etc), the contacts are further recessed inside the device than on a 15 or 20 amp duplex receptacle.
Also when using a wired tester, if the probes have just a small exposed tip, you may not be able to insert the probe far enough get a reading.

Larry McGaugh
4 years ago

All good comments, I come from the HVAC industry and one of the most important recommendations I can make to anyone is always test EVERYTHING before you work on it. This includes circuits where you can see the breaker or switch are in turned off position. I have worked on more that one circuit where the switch or breaker was in the off position and the power was still passing through the device that was in the off position.
TEST-TEST-TEST Never trust any breaker or switch before you test it.

Ron Seidl
4 years ago

Good Discussion Mike,
I work in the Nuclear Power Industry where every possible error must be avoided. We use what is called a Live-Dead-Live check for EVERY voltage measurement test before working on a circuit. As Mike mentioned, first check a known live circuit, then check the one you will be working on, and then again check a known live circuit with the same measurement device.

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