RV Electricity: Better 30-amp power connectors


By Mike Sokol

Dear forum members,
We woke this morning with no electric. The issue was a poor connection of the electric cord to the RV. I tried to disconnect the electrical cord from the RV, but it would not release (it is not the screw on connector being on). I am at a loss of how to get it removed. Wiggling the cord did get the electric back on, but I really wanted to remove the cord and replace it with a spare with the assumption that maybe something is wrong with the cord. The only thing I can think of to do at this point is remove the connector, but I wanted to see if anyone has other options or has had this issue. What do I need to do so this won’t happen again? —Robert

Dear Robert,
I always get these types of questions midsummer when everyone is running the air conditioners in their RVs. That draws a lot of amperage, which can be compounded by campgrounds with low voltage causing your air conditioner compressors to draw even more current than normal.

I’m getting reports of campground pedestals routinely dropping to below 95 volts during the hottest times of the day, which only makes the problem of shore power cords melting and the contacts melting together even worse.

You need to make sure the pedestal power is off, remove the plug from the pedestal outlet, then remove the welded-in shore power plug from the side of your RV. Something will probably break inside of the connector when you take it apart, but it’s ruined already so getting it apart without damaging the exterior of your RV is the best you can probably do. Unfortunately, if one of the connectors is visibly damaged, you really need to replace both the female plug on the end of the cord, as well as the male inlet on the side of the RV. If one of the connectors overheated enough to show visible damage, then it’s likely that the other side is damaged as well. So replacing both mating connectors at the same time if one of them failed is the safest policy.

Now, as to what causes this type of failure. I’ve done a lot of studying about it and have come up with a few possible causes and solutions. I say “possible” because there’s a lot of variables with this type failure, and in many cases it might take a few things going wrong at the same time to create an actual meltdown and welded contacts.

The standard 30-amp inlet on many RVs is a NEMA L5-30R receptacle. Because this is an inlet connector it will have male contacts that are visible when you open the waterproof door. And if you look closely you’ll note that the contacts are curved so the plug can be twisted just a little bit clockwise to lock it in. There’s also a locking ring on the outside of the housing which allows you to cinch down on the shore power cord plug after inserting it into the inlet (and properly twist-locking it).

Believe it or not, I have dozens of emails from readers who were unaware that (A) you need to twist the plug to lock it, and (B) you need to spin on the locking ring to provide a waterproof connection that can support the weight of the cable without bending the contacts.

As for (A), twisting the plug to lock it in, my readers claim nobody told them it needed to be twisted to establish a solid electrical connection. By not twisting the “twist lock” plug to make the connection, there will be less surface area in the contacts for the current to flow through and overheating can result. So make sure you always give it a good “twist” for about 1/8″ until you feel it actually lock in.

And for (B), spinning on the locking ring, a least several readers admitted to being a little lazy and not wanting to spend the extra 10 seconds it takes to do this properly. Without that locking ring to support the weight of the heavy shore power cable, you’ll be bending the contacts and reducing the surface area for current flow. Again, reduced contact area in the wiring is what causes heating and melting of the shore power connector on your RV, and possible welding together of the contacts themselves.

Next, let’s talk about corrosion/oxidation. Shore power cords lead a sad life. They’re always laying on the ground, often walked on and driven over, and many times the connectors on the end are left out in the elements for rain and everything else to get into them. Then they’re often unceremoniously dumped in the RV storage bin to bask in even more moist air. That moisture will eventually corrode the connections inside, leading to increased resistance, and … wait for it … connector overheating and a meltdown. Ugh!

While the ends of your shore power cordset should be relatively protected from rain while they’re connected to a pedestal and your RV power inlet, you don’t want to leave the unconnected ends laying on the ground exposed to the elements. More corrosion means more contact resistance, which means more overheating and meltdowns.

I’ve covered this many times already in previous columns, but you really should use a good contact cleaner and lubricant on your shore power connectors at least several times a season (once a month, perhaps). I use DeoxIT D5 all the time, but you can also use CRC Contact Cleaner followed up with a spritz of CRC Heavy-Duty Silicone Spray, which are available in any auto parts store. Read more about contact cleaning trailer connectors HERE. I don’t have an article specifically about cleaning shore power connections yet, but I’ll write one and make a video on the procedure for my next RVelectricity newsletter which will publish the last Sunday in July.

Next, if you’ve had one part of your shore power cord overheat and/or melt, then you need to replace both parts of the connection. I suggest this is a good time to upgrade to a Marine Duty 30-amp connector. While a little pricey, I really think the SmartPlug connector is superior to the NEMA twist lock plug for several reasons.

First, you don’t have to twist it to lock it in – just give it a push until you hear it click. Also, there’s no locking ring since closing the access door locks the plug housing. It has 20 times the contact area of a standard NEMA twist lock plug, and electrical contact area is the best way to reduce resistance and the resultant overheating.

The SmartPlug contact material is also rated for marine duty, so corrosion-induced resistance and overheating should be eliminated. It’s the same form factor as the twist-lock inlet you’ve removed from your RV, so it’s a simple task to install it in the existing mounting hole.

I need to do some destructive testing on my own to say just how tough these are, but the SmartPlug connectors seem to be built like a tank, so it’s safe to say that they should save you from having to replace your shore power cord and inlet a third time. And yes, SmartPlug makes 50-amp versions as well. Find out more about the SmartPlug technology HERE or purchase one HERE for 30-amp or HERE for 50-amp.

Hope this answers your questions and gives you a good alternative.

See you all next week. In the meantime let’s play safe out there….


Mike Sokol is an electrical and professional sound expert with 40+ 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.


Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.

newest oldest most voted
Notify of
Lance Leroy

We’re full-timers for the past two years using the 50 amp Smart Plug and cord. Not only the cord is very flexible and lighter than other brands. In my opinion it is the best and safest RV plug on the market today.

Dave Telenko

Hi Mike, as I read about the smart plug I was wondering what the contact material was. It says its for marine duty, so corrosion-induced resistance and overheating should be eliminated. So HOW do they do that?

Deborah Mason

When we bought our RV (2011) we invested in a $300 “surge protector” that analyses the circuit before allowing power to the rig. It has saved our butts repeatedly. We had an RV plug installed at my sister’s & it was not installed correctly (240 on both legs!) so we were saved from fried components. The electrician returned, looked, said “hmm” and fixed it. Recently, at our house, the power coop’s transformer was feeding us too much power and the RV protector reported by how much. (Our stove’s oven circuit was reporting “high voltage” & beeping at 2am, had to unplug it to get any relief, the coffee pot clock was crazy. By knowing how much too high, we got them to fix the power sooner. We’ve also plugged in at RV parks & found the power to have problems. It has been our first line of protection and well worth every penny.


Just for arguments sake- I tend to think that it’s the opposite end of the shore power cord that is more commonly a problem. In any case, the real solution to the issue described here is to have a a cord hard wired with a compartment built to keep it in while traveling.


Mike: For those people who have the standard 30 or 50 Amp Connectors on their RVs, they might want to consider the 90 degree Adapter that plugs in and then hangs down to remove the Cord Strain and thus save your power cord for longer use.

The 90 degree adapters can be purchased from CAMCO and are not that expensive.

Just a thought.