Melting power plugs

[dkperez]

I found a couple topics about problems with RV plugs, but most seemed to be from situations where line voltage went way down or they were trying to draw more than 30A.


I have a small 5th wheel. 30 amp cable/plug. Ordinary stuff drawing electricity. Inverter that keeps the batteries charged, 13.5 Kbtu A/C. Not much else I can think of off-hand. The hot water heater and refrigerator can run off 120V, but we don’t normally do that when using the A/C.


I’ve NEVER had the 30 amp breaker on the power pole blow. I’ve also NEVER had the 30 amp breaker in the trailer blow. Neither. Ever.


Occasionally, we’re too far from the power pole and use a 30A extension, but that’s never caused any problems or melted or done anything strange.


A couple years ago I added Surge Guard Model 34830, 30 amp surge protector. I never had any problem with the voltage shown at any campground, but I read so much about bad power that I bought one.


As I recall, the MOST it ever showed for draw was about 24 amps – and that was WITH the frig on 120V.



On one trip, after a few days at a campground in MN, with the A/C on, (water heater and frig on propane) the plug from the trailer was welded into the receptacle on the surge protector. Was a big PITA to get it apart. Surge protector plug was so bad I had to cut it off and toss it. Plug from the trailer was also bad and had to be replaced.


We’ve been using it this year and haven't had any problems 'til recently, but last time out it did the same thing again. Even without the surge protector – going straight into the pole, the last time out the trailer plug was discolored and showed melting.


The metal prongs on all the plugs and receptacles look fine – no corrosion or crud.


How do I keep this thing from damaging power plugs? Same question for the new receptacle on the surge protector? Is there some magic I'm missing or something I should use on the prongs so they make good contact and don't overheat? Or what?

[code2e]

You are dealing with a lack of "pin tension". That is how receptacles and plugs connect. The plug on your shore power cord is the only part you have direct control over at an RV park. Ideally your plug will have the thickest prongs possible and be electrically clean. Always only plug in or out with the post breaker off to eliminate arcing.

The RV park receptacle contains the female connections that provide the grip on your plug's prongs. You may be able to tell the condition of those connectors by the feel of plugging into it. There should be some resistance as you plug in. It's those connectors that have the spring tension to make a good connection.

You can make it a practice to plug and unplug twice with the breaker off. That provides a scraping action to freshen up the metal surfaces. If you find your plug is a loose fit, you should tell the park office. Maybe move sites. Maybe they can swap the receptacle out.

Any poor connection will build heat while under a load. Your welded plug/surge protector for example. Tight, clean connections remain cool.

[Argosy]

If you tossed the plug that was on the cord plugged into the surge surpressor did you also change the one in the surge supressor?

[sibe]

The Receptacle (female) end of RV ParK or you surge Protector is loosing tension as stated .. IF you are pulling that 20-24 amps on a long cord into the surge or pedestal that is loose.. heat is going to be made..

That surge device is for a lightning strike or huge inrush, it will sacrifice itself and cut power,, upon the first time plugging in it checks polarity and voltage test..
during use if a low voltage occurs , it keeps working,,
That 24 amp at 120V when volts drop to 108-104 which can be common .. the amps reach 27-28, the cord length and the AC compressor cycling with push the circuit to make heat and ANY connection, a loose breaker screw is common but in you case the receptacle end..
Also a common 30A 10/2 wire cord at 25 foot can add a up to 2.8-3.5% voltage drop at load..

IMO

[Terraboat]

As mentioned, you can't control the connection at the power pedestal other than making sure it doesn't look burned in any way and the polarity is correct, however you can upgrade the connection to your RV. Some better manufacturers are starting to install these on their new RVs. Here is why you should too:
https://marinehowto.com/shore-power-...tplug-vs-1938/

[doc]

I have seen female receptacles both 30 and 50 amp burned badly to the point of being loose. More so on the 30 amp. It only takes a second to turn the switch on either off before plugging or unplugging. The plug being hot and a load on the male end will cause and arc and burn both parts of the connection.
Had nice park owner in N Dakota that I mentioned the surge protector was not getting voltage. He moved us to a close by site and came back shortly, thanking me for telling him, saying the receptacle was burned and he found a screw that was not properly tightened inside and the burned connection was having a problem passing power

[NXR]

Originally Posted by dkperez

I found a couple topics about problems with RV plugs, but most seemed to be from situations where line voltage went way down or they were trying to draw more than 30A.

That's never the reason. The metal used in the plug and outlet contacts can handle far more current than they are rated for. Plus there's a circuit breaker at each end to limit the current to a safe level. Melting is a heat problem caused by poor electrical connections or water. Reasons for poor connections:

1. Plugging in or unplugging with the pedestal breaker turned on. That will cause arcing at the contacts. While you may NEVER do this, the people before you undoubtedly are doing that and damaging the outlet that you plug into. Arcing causes damage to the contacts and a poor connection, no matter how good your plug is.

2. Over-use of the outlet, the low contact tension others have mentioned. There's nothing you can do about that except for complaining when you plug in and it just felt too easy. Some 30-amp people will carry a 50-amp to 30-amp dogbone so they can plug their 30-amp RV into the 50-amp pedestal outlet. Those usually are in much better shape mechanically.

3. Over-use of the outlet, again. Shore power cords are heavy. When plugged in the cord is pulling down on the pedestal outlet. Then people yank on the cord to remove it. All of that causes movement at the rear of the outlet where the wiring connects. Eventually the wires loosen up, generating heat.

4. This is a big one: Not protecting from water. You use a portable device so you plugged your cord into it. Is there a cover on your device to keep the rain and other water out? If not, water will cause current to flow between the contacts and generate heat. If the pedestal is too low then your shore power plug and the end of the protection device may be sitting on the ground when it rains. Etc.

5. If your plug was ever replaced, it should have its cover removed once a year and the screw tension checked. Additionally, you should be checking the connection at the other end of the shore power cord if it's easy to get to. Stuff loosens up when it's being towed or driven around. If the person who initially tightened the connections did not use a torque wrench, and almost nobody does and some manufacturers do not even specify a torque, there's a chance the screws will loosen up.

When a fastener is properly torqued, its metal is actually very slightly stretched and that's what keeps the connection tight.

Hope this helps,

Ray

[Dutch Star Don]

Last year at Thanksgiving we were sitting around the fire when my granddaughter said their fifth wheel was full of smoke. When we checked it out, the plug at the rear of the trailer (connector) was burned to a crisp.

The plug had just worn out and was not making a good connection. We did a temporary repair and then my son-in-law added the Smart Plug to the trailer connection. They're about $200.00, but well worth the money.

You said you replaced the plug at the trailer end of the 30-amp cord, but did you replace the trailer end of the connector. Most likely, that is where your bad connection is at.

I would add the Smart plug at the trailer and make sure the shore end of the cable (male plug) is a good quality and the wire lugs are SECURELY tightened on the plug and the Smart plug.

Here is the entire assembly with 30' cord that will replace everything.

https://www.amazon.com/SmartPlug-R30...s%2C127&sr=8-8

[Ray,IN]

Originally Posted by code2e

You are dealing with a lack of "pin tension". That is how receptacles and plugs connect. The plug on your shore power cord is the only part you have direct control over at an RV park. Ideally your plug will have the thickest prongs possible and be electrically clean. Always only plug in or out with the post breaker off to eliminate arcing.

The RV park receptacle contains the female connections that provide the grip on your plug's prongs. You may be able to tell the condition of those connectors by the feel of plugging into it. There should be some resistance as you plug in. It's those connectors that have the spring tension to make a good connection.

You can make it a practice to plug and unplug twice with the breaker off. That provides a scraping action to freshen up the metal surfaces. If you find your plug is a loose fit, you should tell the park office. Maybe move sites. Maybe they can swap the receptacle out.

Any poor connection will build heat while under a load. Your welded plug/surge protector for example. Tight, clean connections remain cool.

Same thing you said in a different format:

I will add, 30A receptacles in RV parks are the most frequently used. This wears out the spring tension of the receptacle and is the cause of melted plug ends.
My solution was to use a 50A to 30A adapter when the 30A is loose in the receptacle. 50A receptacles are less-used and usually have good spring tension in the contacts.
Same applies to adapter plugs.

[Persistent]

Lots of good advice.

Symptoms:
Plug from RV and socket from surge protector fried.
New plug from RV to shore power socket fried.

Cause:
Excessive heat at connections.
One was replaced and another subsequently failed.
Two separate failures. First and second failure are probably coincidental.

May be linked by maintenance and installation of each.
Loose or corroded connections.
Short circuit due to loose strands in connections.
Connections not tight.
Wire not compatible with plug connectors.

[the4quads]

I lost two plugs do to loose receptacles at different locations. One was the from my surge protector and the other from my extension cord. The one on the surge protector was difficult to replace because of the short lead. My solution was to by this 50a male to 50a female extension. I use it as a sacrificial piece. Second benefit is that it straightens out the angle of the plug hanging out of the power box.
Progressive Industries 50AXP Park Power 50 Amp Male - 50 Amp Female RV Extension

I realize that the poster is 30 amp but I would assume they have a 30 version also.

[dkperez]

Thanks for the replies.


I learned in here a long time ago about always shutting off the breakers on the pole before plugging in, so that I do.


I HAVE noticed that a lot of the plugs on shore power are loose. Some of them have broken pieces in the socket and some are just pretty ratty.

Unfortunately, there’s not much I can do about that most of the time. Usually can’t move, and the answer from the office is usually “there’s no one here to do electrical work” or “we’ll try to get that changed next week” or pick your favorite excuse. If it’s a family campground and you’re checking in with an owner, they’re usually more responsive, but if you get a Gen-<pick your favorite letter> drone, you get the blank expression and the don’t-give-a-feces shrug. But yeah, some of the plugs are “less than optimal”…


I HADN’T thought of plugging and unplugging a couple times to scrape off some of the smutch that may be in the socket. I’ll definitely start doing that. I saw a video where a guy took a cheap 30A adapter and cut notches in the prongs with a triangular file so he could push it into the shore power a few times and scrape off some of the junk.

Any poor connection will build heat while under a load. Your welded plug/surge protector for example. Tight, clean connections remain cool.

Except in this case both parts of the connection were clean – the surge protector was new, and the trailer plug was clean. It plugged together well.

That’s the part I’m not getting – if it has been loose and floppy I could see it, but it wasn’t.



I had to toss the receptacle from the surge suppressor – it wasn’t even functional any more. I also had to change the plug on the trailer cord. And it’s been working, til the last place I was. Everything seemed fine, but the plug was damaged when I pulled it out.

IMG_20220911_155013994_HDR.jpg


IMG_20220911_154947639_HDR.jpg


Is there a good way to CLEAN the contacts inside the receptacle? I know I can use a brass wire brush on the prongs of the plug, but what do with the receptacle?


I THOUGHT I had a replacement receptacle for the surge protector, and I do, somewhere. But the piece of cable coming out of the surge protector is so short after cutting off the old receptacle that I can’t get the new one on. I just ordered a short adapter with cable that will be long enough to cut off and replace in the surge protector.

Seems like there should be some kind of cleaner or SOMETHING you can put on the prongs to get a better connection, but I haven't seen anything.

[code2e]

Originally Posted by dkperez

Thanks for the replies

Except in this case both parts of the connection were clean – the surge protector was new, and the trailer plug was clean. It plugged together well.

That’s the part I’m not getting – if it has been loose and floppy I could see it, but it wasn’t.



Is there a good way to CLEAN the contacts inside the receptacle? I know I can use a brass wire brush on the prongs of the plug, but what do with the receptacle?
[/I]

Since your plug and receptacle contacts were clean and tight. It may have been the wire connection to the prongs inside your plug? Poor connection there would build heat in prongs and transfer to receptacle contacts.

I would not probe the receptacle with anything besides the plug, myself. Safety concern. There are good electrical contact cleaners. My favorite is DeoxIT D5. You could spray a bit in each hole. It works and dries fast. You will find many uses on your coach, once you try it. Available on Amazon.

[dkperez]

On our trailer there IS no connection at the trailer. The cord runs through a hole in the side and is wired into a junction box where the cord is stored.


So, I only have a plug on the end that goes to the power pole.



I also just ordered a 30A to 30A adapter with a longer cord so I can replace the socket on the Surge Protector.



I'll definitely get some of the DeoxIT.


As far as the wires connected in the plug. There were good and tight BUT they weren't tinned (I'm not sure why the never recommend tinning the wires going into these kind of things), and when I pulled them out there was a little black corrosion on a couple.



On the new plug I used thin ferules over the wires before clamping them down, though I'm NOT real impressed with the plug I just put on - I don't like the way the ground prong is attached to the clamp part...


I ordered a new, different plug for a spare.