Troubleshooting Electrical Problems - When in Doubt - Don't

[Steven@147]

I have noticed recent threads on outlets not working and 12V lights inop and such. Our RVs operate on 12VDC and 110-120VAC. Maybe a good time to caution owners that don't know much about electricity. When in doubt - don't!
Get someone who knows electricity to TS. I'll go out on a limb and say all electricity is dangerous DC and AC to an inexperienced person. Not just to your person but to the device you are messing with. Those of us that have been around it know that it isn't necessarily but forget the nuances and detailed explanations and theory. Its dangerous to the inexperienced.

Multimeters - good tool to have around but know how to use them. If you get a cheap one they do not have safety circuits, you could blow the meter by connecting it wrong or moving the meter dial from different voltage settings or to resistance when connected to a circuit. If you have blown your meter and are checking for voltage you may think the circuit is dead, but it isn't. And for the inexperienced people do not check for amperage unless you know what you are doing.

For the inexperienced it is better to get a simple plug in type tester with pass/fail or little lights, some simple plug in device you can just plug into an AC outlet to see if there is power. If you cant find a circuit breaker or GFCI tripped, and you have reset or cycled the breakers and outlets, call a professional. Same with 12VDC fuses, if you have changed the fuse and it still doesn't work stop, and call a professional. Never replace a 12VDC fuse with a different rated one even just for checking. And by all means Stay out of the campground power pedestal.

For the 12V DC 7 way truck plug there are simple testers you can just plug in and check it. If the test light comes on, its good.

I don't want to see or hear about anyone getting hurt or burning up their wiring. I have seen some pretty stupid things done and I will not tell you about them because someone will try it.

Just a caution.

[traveldawg]

Good post/reminder..... To quote Dirty Harry.... "...a man has got to know his limitations..."

Another suggestion is to pay a little less attention to all the folks on YouTube these days who think they know what they are doing and making video after video just to get your attention (and vote) without offering much of a hint of what can go wrong (or did that got edited out).

[boyscout]

So @Steven@147 are you saying that it might be dangerous to check for power by touching wires to our tongues the way we do 9-volt batteries?

Good post. Good advice to get a quality multimeter but I'll throw out a different suggestion for those who don't already have such a tool. Instead get a good clamp meter that does DC as well as AC current measurement (they don't all measure DC but trailer owners need that).

Expensive though they are, good AC/DC clamp meters will do the basic voltage and continuity and resistance measurements of a multimeter but they'll also do current measurement. It's often useful - especially when dealing with battery-supplied DC circuits but also with AC circuits - to know how much electricity is flowing through the trailer's wiring / being drawn by your trailer's equipment.

This one is a good choice:

https://www.amazon.com/Ideal-Industr...3059118&sr=8-2

This one is nicer with a detachable display (no more, "ok honey, turn it on now, NO, QUICK, turn it OFF!!") and a flexible hoop (for AC only unfortunately) for working in tight spaces.

https://www.amazon.com/Fluke-381-Rem...3060191&sr=8-1

[Steven@147]

So @Steven@147 are you saying that it might be dangerous to check for power by touching wires to our tongues the way we do 9-volt batteries?

Good post. Good advice to get a quality multimeter but I'll throw out a different suggestion for those who don't already have such a tool. Instead get a good clamp meter that does DC as well as AC current measurement (they don't all measure DC but trailer owners need that).

Expensive though they are, good AC/DC clamp meters will do the basic voltage and continuity and resistance measurements of a multimeter but they'll also do current measurement. It's often useful - especially when dealing with battery-supplied DC circuits but also with AC circuits - to know how much electricity is flowing through the trailer's wiring / being drawn by your trailer's equipment.

This one is a good choice:

https://www.amazon.com/Ideal-Industr...3059118&sr=8-2

This one is nicer with a detachable display (no more, "ok honey, turn it on now, NO, QUICK, turn it OFF!!") and a flexible hoop (for AC only unfortunately) for working in tight spaces.

https://www.amazon.com/Fluke-381-Rem...3060191&sr=8-1

LOL - I once knew a guy who put a 9 volt battery in his pants pocket (why I don't know) and a dime got wedged between the terminals, instant hot leg!
When I wrote that I was kind of thinking of a couple family members I have. They should just stay away from electricity of any kind. Even if they got a "meter for dummies" they wouldn't know what it was telling them.

In a shop I use to work at there was a safety picture of a wedding ring welded to a wrench. I know a young guy that lost both of his arms because he used an aluminum ladder next to his house power lines. Saw a different guy slapping wires on metal to see if it sparks, YUP, its got power!

A lot of the electronic control boards in our RVs can be destroyed by static electricity, improper handling, unstable voltages or somebody using a meter that don't know what they are doing. We used anti-static mats and grounded wrist straps when I worked for a computer company. The more electronic crap they put into our RVs the more vulnerable they are, and less tolerant with poorly made electronic components. Example of the Chinese electronics company who stole the formula for making diodes from a Japanese electronics company. What they didn't know was, it wasn't the complete formula. Next thing you know we had Chinese manufactured circuit boards with diodes popping like popcorn! That caused a real stir in the electronics industry back in the late 90s!

[jmbopp]

" I once knew a guy who put a 9 volt battery in his pants pocket (why I don't know) and a dime got wedged between the terminals, instant hot leg!"

Or the guy who had a 9V battery and a live .38 round in his pocket that cooked off.

[xrated]

And another "good practice" to follow when using any type of metering device. Check the device on a known voltage source that is "hot". Do whatever tests or take whatever readings you need to do. When you are finished with that, check to meter again to make sure it is still working. If something happens to the meter while you are troubleshooting, it may cause you to believe that a circuit is dead, when it may in fact still have voltage on it. I've been an Electrician for almost 40 years, and trust me, you don't get to be an old electrician by doing stupid things.