RV Electricity – Just Ask Mike (J.A.M.): What’s that burned wiring smell?

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By Mike Sokol

Welcome to my J.A.M. (Just Ask Mike) Session, a weekly column where I answer your basic electrical questions. If you’re a newbie who’s never plugged in a shore power cord (or ask – what’s a shore power cord?), or wonder why your daughter’s hair dryer keeps tripping the circuit breaker, this column is for you. Send your questions to Mike Sokol at mike (at) noshockzone.org with the subject line – JAM.


The following just showed up on my RV Electricity Facebook Group this week, and it’s a good reminder to never ignore any burned electrical smells. Read and heed below.

Dear Mike,

I found this… I was noticing some heat and smell from the panel when running the A/C for long periods. This is a 30-amp setup and it’s been fine. I found the neutral terminal screw for the main feed was pretty loose. Would that cause the heat buildup or should I be looking at something else? I’m pretty certain it was just from a loose contact. Cut and re-stripped the wire and will run things again to see if it gets warm. I’m just happy that I noticed. Any thoughts would be appreciated! Thanks. —Scott

Dear Scott,

Your quick action saved your power panel from additional damage, and possibly prevented a fire in your RV if it had been left unchecked. So, great job on realizing that hot electrical smells in your RV usually mean trouble. It’s always best to check.

We cover this sort of thing in a lot more depth on my RVelectricity Facebook Group and my RV Electricity Newsletter, but the basics are that any loose electrical connection will tend to heat up and can cause damage to the wiring. That’s why I suggest that all electrical screws in your power panel should be checked for tightness at least once a season. While it’s true that you don’t have to do this sort of thing in your sticks-and-bricks house, it’s not bouncing down the highway possibly thousands of miles a year and going through temperature swings from below 0 to above 100 degrees like the electrical system in your RV. All that vibration and the hot/cold temperature swings tend to loosen up your electrical connectors.

However, as I’ve written before, you just don’t want to get cranking and possibly over-torque the terminating screws – which can cause more problems if you strip them, and possibly break off a relay terminal in your Automatic Transfer Switch (ATS). That’s expensive and can leave you without power until you get a replacement unit, so don’t go there.

And make sure you have and use the correct type of bit (usually square) in the screwdriver (not just a flat blade) since you don’t want to damage the terminating screws by slipping off of them. Some of the damage I see by casual “non-electricians” is pretty sad and unnecessary if only they had used the right tools in the first place.

I also highly recommend you use a torque limiting screwdriver set to the correct torque, which is usually around 35 in/lbs (not ft/lbs), and often marked right inside the cover of your ATS. I have an industrial duty torque screwdriver for my own work, but that’s probably overkill for the average user. So, as I’ve noted here before, you can get a nice one made for gunsmiths for less than $50 which should do the trick. You can get one HERE.

Also, if any of the wires were damaged from overheating like the one in the picture, you need to cut them back to get to the unburned insulation and fresh copper. If it’s then too short to make the connection, I recommend you use WAGO lever splice connectors inside of the box to add on a length of the proper gauge and color wire. WAGO lever splice connectors are available on Amazon.com and other electrical parts houses, and are really handy for this sort of splice.

Finally, make sure ALL power is off before you even open up a panel as those are deadly voltages inside, and you’ll be reaching in with a metal screwdriver. So, disconnect from shore power, generator power and inverter power. Any of the above can kill you.

OK, everyone. Remember that electricity is a useful and powerful force, so we all need to pay attention to safety precautions while using it.

Let’s play safe out there….

 

 

Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.

For information on how to support RVelectricity and No~Shock~Zone articles, seminars and videos, please click the I Like Mike Campaign.

##RVDT 1247;##RVT 930

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Walt
8 months ago

When I was working in the commercial HVAC industry, one of the tasks we performed each spring was a maintenance procedure for our customers’ refrigeration and AC equipment. This ALWAYS involved checking EVERY electrical connection for tightness and/or signs of overheating. It amazed me, the “new guy,” how many connections we’d find that had loosened up. They do need periodic inspection!

TravelingMan
8 months ago

Folks, these are cheaply made RV’s. The manufacturers have very limited rules to follow (as you can probably already see). We full time…We have had so many electrical problems from:

1) Undersized wires
2) Loose terminals crimped onto wires to connect to light switches
3) Wires burned off on the back of these cheap electrical outlets that stab in without sufficient pressure
4) High resistance (burned connectors) in the 120V splice connectors under the bed and that are used to connect the slide out to the RV
5) 12V lights with burned lamp fittings
6) 120V Power cord connectors with burned wire
7) Burned light switches
8) Panel wires loose and showing signs of overheating

One really should take all light switches, receptacles and plugs apart to verify tightness when they do the PDI at pickup. Then, do the same as a maintenance task about every 2 to 3 years until problems are eliminated. It may seem excessive to some, but keep in mind you have about 20 seconds once the RV catches fire to get out.

And if you use a 50A cord, either get a cord that has a 90 degree head on it or get the 90 degree adapter. Take the pressure of all that weight hanging out there. It’s creating a problem with overheating your connector body.

These RVs are not houses. They are “temporary” structures. Take care with electrical items in your RV.

JBC
8 months ago

Mike – an excellent piece today. One question, and I know this may sound obvious but I need to check. You say, “So, disconnect from shore power, generator power and inverter power. Any of the above can kill you.” Shore power is obvious but the other two I could use some help with. I have a HR 23′ Aluma-Lite motorhome. How do I assure the generator and inverter are disconnected?

Bill
8 months ago
Reply to  JBC

They both have off switches, the generator has a circuit breaker switch or two on its’ control panel, and the inverter may supply a separate panel with a master circuit breaker. Make sure all are off, and if you have automatic generator start make sure it is disabled (programmed to off) also. Then check with your voltmeter to make sure there is no voltage before you stick anything else (including your fingers) in there.

On second thought, if you have to ask the question, get a qualified technician to do it for you. If you pay him enough, he may let you watch. 🙂

DAD
8 months ago

I had a burning smell from my AC last year and not much later it quit.
Should have checked it right away as the Hot wire in the control box was melted