Smoke and Fire After Plugging In

[Kevin Means]

Here's a long one, but I think it's worth reading, because it applies to a lot of us. See if you can figure out what caused this problem before I tell you.

Cyndi and I had promised our 6 year old grand daughter that we'd take her camping - just the three of us, so off we went this weekend to a local County campground. Once there, I plugged our Progressive portable surge guard unit into the 50 amp power pedestal, as I've done countless times. I waited for it to indicate that the power was OK, and to transfer power to the coach. When it did, I went inside to the One-Place panel and turned on the two front AC units.

There was the normal 30 second delay (or so) and then the two forward AC units kicked on. I was about to start some other tasks when I noticed that the Magnum inverter's remote had a "High ACV" error message and a warning light, and the inverter had shut itself off. "Huh?" First time I'd ever seen that.

Then a loud, rapid clicking noise started up in the rear bathroom. It was the washing machine's electric door latch, locking and unlocking on its own - about once every half second. The odd thing was, the washing machine's power was off, and the On/Off switch wasn't responding. Then, "Bang!" The clicking noise stopped and I could see a small flame lapping up from under the washer's tumbler. Uh oh!

I yanked the washer and dryer's power cords out of their sockets, then rapidly moved to the foot of the bed to manually trip their circuit breakers and get a nearby fire extinguisher. (The breakers hadn't tripped on their own.) As I was doing so, I saw smoke coming out of the AC roof air ducts, so I tripped their breakers too. The flames in the washing machine went out on their own after about 10 seconds.

I thought, "What the hell is going on!" I turned on the roof vents to dissipate the acrid odor and smoke (it smelled electrical) and I told Cyndi and Jo Jo (our grand daughter) to stay outside while I troubleshot.

I re-checked the Progressive surge guard, and it still indicated that all was well - 119 volts on each line and no errors. Stumped, I disconnected from shore power, visually checked the transfer switch to verify that there were no obvious problems (burn marks, smoke, odors etc.) and there were none. I checked the Magnum remote again, and the high voltage warning message was gone.

I started the generator and it powered everything just fine - with no inverter error messages. (I didn't check the washer - I knew it was toast.) All three AC units worked, and there was no more smoke coming from the vents.

I started to focus on the Progressive surge guard, thinking it was somehow malfunctioning and letting bad power into the coach. As a simple test, I disconnected the surge guard and plugged the power cord directly into the power pedestal. Everything in the coach worked fine. To confirm my suspicion that the surge guard was malfunctioning, I plugged the power cord back into the surge guard and discovered that I now had power to some circuits in the coach, but not to everything, and there were no high voltage error messages. That made no sense to me.

Then it struck me... there's one component that could cause these problems - the power cord plug. I disassembled it and sure enough, the white wire was loose. There were indications of significant arcing and there were burn marks on other wires. It was a Camco plug and I installed it about four years ago. 

I'm no electrician, but it appears to me that, somehow, the loose wire was shorting out and causing 240 volts to get to the coach. That's the only thing I can think of that would cause the Magnum inverter's high voltage error message and its automatic shut-down. It would also explain the electrical overload of the washing machine and the smoke from the AC ducts. After removing all the covers from the AC units, I found that the armature on one of the condensation water pumps had burned up. Apparently, that's what caused the smoke.

If someone's got a better explanation, I'm all ears.

So in the end, my portable Progressive surge guard was working fine, but I assumed it would prevent all electrical problems from getting to the coach. The truth is, portable units only prevent some electrical problems from getting to the coach. A downstream short circuit - even as close as the adjascent power cord plug (a $30.00 part) can wreak havoc. I'm replacing my portable unit with a permanently mounted unit - installed downstream from the power cord plug. It would have detected the high voltage problem and not allowed power to flow to the coach. It would have been a real shame if that fire had gotten out of control and destroyed the coach. 

Kev

 

[RVMommaTo6]

Whoa! Was there any way to see that coming? It sounds like the kind of thing that's impossible to predict.

 

[garyb1st]

Wow, that's a scary one.  Glad you sorted it out and everyone is OK.  It makes me wonder about the plug I just replaced on my 30 amp cord.  Haven't used it yet since I replaced the cord before fixing the old one. 
Take care and enjoy the rest of your camping trip.  Hope the granddaughter has fun.

Gary

 

[BigDaddy48]

Here's a good article on the possibilities of an open neutral with an RV pedestal providing a 50A connection.

https://rvtravel.com/do-i-need-an-intelligent-surge-protector-for-50-amp-shore-power/

 

[Seilerbird]

I was thinking 240 about half way through the explanation. Sounds about right to me as an electrician. There is a huge problem with electrical plugs that you have to tighten up the screws to make contact. In order to tighten it up tight enough you must hold the plug in your hand and turn the screw driver. If you use too much pressure you run the risk of slipping and running the screwdriver through your hand, not enough pressure and you end up with electrical problems down the road. There was a thread here recently where someone had a bad cord and wanted to replace just the plug. I was going to recommend that he replace the entire cord but I decided not to because I was positive I would get some negative reactions. Plugs like that should never be used on an RV due to the vibration that the plug endures while driving it down the road. Same reason you should not solder electrical connections or use wire nuts on RV electric.

 

[Robert K1]

Here's a good article on the possibilities of an open neutral with an RV pedestal providing a 50A connection.

https://rvtravel.com/do-i-need-an-intelligent-surge-protector-for-50-amp-shore-power/

  That is a very easy to understand article and timely for me. My old power management box died on me this past trip.  I picked up some insulated lugs and bypassed to transfer switch.
Ordered a new 50 amp surge guard before we left campground.
  I think I will leave home shore power unplugged till new unit is installed

 

[triplethreat]

The plugs that are moulded onto the manufactured cords are something that you cannot really check....the plugs are moulded on...duh!  But, if you replace one of those plugs with the type that you open up then put the wires under screw terminals, it is always a good idea to open the plug(s) back up occasionally and check the terminals for tightness.  It only takes a few minutes for each plug and is well worth your time.  Loose connections can cause arcing, burning, and in the case above, an open neutral....which will case the voltage to go high....which of course causes all kinds of other problems.

 

[Alpena Jeff]

Yikes! Hope you brought extra underware Kev. :

 

[Primerump]

my first thoughts were a dropped neutral.

Kudos for containing the situation quickly, that could have turned ugly real fast..

time to invest in a plug with phase/voltage monitoring and relay disconnect..

 

[John From Detroit]

Your theory is close very close and your diagnosis procedure is fantastic.

Think of your electrical system like a plumbing system

You have a big tank
it feeds a pump. that PUSHES water at 120 PSI into a pipe.
T-ed off this pipe are assorted things like your A/C. Fridge TV, Water heater
Then there id another T with a pipe (painted white) that runs back to the tank.

And a 2nd pump, the main pipe continues on to more T's. The other A/C, teh MIcrowave, other outlets.
It then goes to a 2nd piump this one sucking to the tune of -120 PSI.

The other side of all the devices powered goes back to teh white pipe.

Now. if the white pipe is "Broken" (plugged at teh tank)  and your two legs are drawing EXACTLY the same number of GPM. then the pressure in the white pipe is zero and no water flows. so it's not a problem.. this is also next to impossible to attain.

But if one leg has more load than the other.. Then that leg will have less pressure. and the other leg more

Another way to look at it.

0-----------------------------120------------------------240

The number in the middle is the neutral

IF it is properly bonded to the park. IT will always be in the middle
If the two legs are prefectly balanced it will be in the middle. But

0=======60 - - - - - - - - - - - - - - - - - - - - - 180

If the loads are not balanced (As shown by the HEAVY == v/s the lighter - - ) as you see "neutral" moved  And smoke gets released on the light side.

Electronics run on magic smoke. We know this because when you let it escape.. They quit working.

 

[triplethreat]

Your theory is close very close and your diagnosis procedure is fantastic.

Think of your electrical system like a plumbing system

You have a big tank
it feeds a pump. that PUSHES water at 120 PSI into a pipe.
T-ed off this pipe are assorted things like your A/C. Fridge TV, Water heater
Then there id another T with a pipe (painted white) that runs back to the tank.

And a 2nd pump, the main pipe continues on to more T's. The other A/C, teh MIcrowave, other outlets.
It then goes to a 2nd piump this one sucking to the tune of -120 PSI.

The other side of all the devices powered goes back to teh white pipe.

Now. if the white pipe is "Broken" (plugged at teh tank)  and your two legs are drawing EXACTLY the same number of GPM. then the pressure in the white pipe is zero and no water flows. so it's not a problem.. this is also next to impossible to attain.

But if one leg has more load than the other.. Then that leg will have less pressure. and the other leg more

Another way to look at it.

0-----------------------------120------------------------240

The number in the middle is the neutral

IF it is properly bonded to the park. IT will always be in the middle
If the two legs are prefectly balanced it will be in the middle. But

0=======60 - - - - - - - - - - - - - - - - - - - - - 180

If the loads are not balanced (As shown by the HEAVY == v/s the lighter - - ) as you see "neutral" moved  And smoke gets released on the light side.

Electronics run on magic smoke. We know this because when you let it escape.. They quit working.

You sure like to complicate things.....

 

[johnhicks]

  I had a portable 30A Progressive EMS; the RV cord developed an intermittent arc that burned the plug, the socket on the EMS and the EMS plug. I replaced the unit with a hard-wired version.

 

[Rene T]

I'm still a little confused about exactly what happened but I do know that I wished now, I had purchased the hardwired model of the Progressive. I now have the portable one. I don't believe I'll have any issues. My trailer end of the cord plugs straight into the RV receptacle and I've always tied up the cord to my bike rack to take the strain off the plug.  The other end is a 90 degree plug which plugs into the Progressive and just hangs down.

 

[Back2PA]

Wow Kevin, that could have been really bad.


Wasn't cord related but I'm 99% certain I had an intermittent bad neutral on a pedestal early in the year, that only showed up under load. Came back to RV with 230 showing on plug in volt meters. (Didn't have a Progressive, only a surge protector.) Took out inverter, charger, microwave and surge "protector". When voltage was checked at pedestal after I unplugged both legs read fine so park (a very high-end one BTW) took no responsibility.

 

[Gary RV_Wizard]

This is a classic "open neutral" fault in a 240v system (e.g. the RV 50A hook-up).  It happens when the neutral wire is disconnected or badly corroded.  In essence, the voltage in each hot wire varies inversely with the amp load on each (the hot wire with the higher amp loads is lower in voltage).  The voltage on one hot goes up while the other goes down.  It takes a substantial amperage difference between the two hots to push the voltage up/down enough to cause a problem, usually more than 15A difference.  That means things may seem fine for awhile and then suddenly go whacko when you flip a switch or a thermostat cuts in.


The Progressive EMS often misses this problem if the white neutral connection is intermittently there but poor quality (loose or corroded wire). It verifies that a neutral is present and the voltages are OK until a large load is applied on one leg or the other.  If the bad neutral is upstream from the EMS, it should see the voltage change as it occurs and open the circuit, but if the fault is between the EMS and the coach or in the coach load center, it probably won't detect the voltage problem.


Here's another story similar to Kevins, reported by a guy who knows his electricity well.
http://www.myrv.us/electric/Pg/open_neutral.htm

 

[PlowHand]

So what can a guy like me that doesn?t understand very much of what has been said here do to prevent this from happening to me? Is there a product that can fix this? Is there a higher quality cord I can buy? Please make your suggestion simple enough that a lay person can know what to go buy that can protect me and my family/rig.

 

[Alpena Jeff]

Agree with plowhand. My first reaction wound have been.....RUN to unplug or turn off breaker.
Right or wrong?
So much to learn.

 

[CamperAL]

Hi,

I'll inject my 2 cents but may not be qualified in regards to electrical matters. I figure if Kev had trouble many people here on the forum would have had trouble trying to figure out the problem on this.

My progressive unit is 30 amp. It is a plug in unit and not hard wired. I leave my unit plugged in all the time and take my extension cord and plug that into the power at the campground. This does two things, keeps it safer from theft and keeps it inside the compartment. Also should not ware out as fast as it is always plugged in. Sometimes I have to unplug and attach to pole power when I need the added length.

Be Safe!

 

[Gary RV_Wizard]

This is a situation where a hidden something breaks.  There isn't a lot you can do except be observant for signs of wear on the plug-ends of your 50A power cord and any oddball power problems/symptoms.  The broken something may be in the campsite power pedestal rather than your RV, so even the best preventive maintenance may not protect you.  A powerline monitor (Surge Guard or Progressive EMS) will catch some occurrences, and it is slightly more effective if installed at the coach power entry rather than plugged to the power pedestal.

RV power cords are subject to a lot of flexing at the plug end and that tends to break the wires where they connect internally to the pins on the plug.  Watch for signs of damage, e.g. overheating of the plug, insulation pulling away at the connection, exposed wires, and loose or burned pins on the plug. Replace the plug if in any doubt.


Also: this type of high voltage problem occurs only with 50A/240v shore power.  Loss of the neutral on a 30A/120v connection merely causes a total loss of power to the coach.

 

[Isaac-1]

I guess the question we should all ask:

Is there a better quality 50 amp RV plug out there than the cheaply built yellow Camco plugs?  I replaced one last year on my coach and was not impressed about the en-cheapening of the Camco plug I installed vs the only slightly better looking Camco plug it replaced.