New Problem....Weird Electrical Glitch

[Dick Simonis]

On our way home from Parker, we stopped in Goodyear for a couple of days to visit some friends and play a bit of golf.  Got back to the coach after good golf and great dinner to a MH with no power and a burnt smell inside.  After 3 hours I still can't figure out exactly what's going on but here are the symptoms.

The 50A breaker on the pedestal was tripped and a reset did no good.  Shore power doesn't feed anything.
The inverter will supply power to all the correct outlets.
All the GFI's for the galley were tripped
The genny will power up the A/C units, and HW heater but will not supply power to any outlets that the inverter will power...like the galley.  The Genny will power the other outlets, typically on the passenger side.  AC lights will work on inverter but not on genny.

I did find a power strip in the forward overhead compartments that appears to be the source of the burnt odor as it's pretty much destroyed and also melted some other wires up there.  No doubt this is a problem and we're fortunate that a fire didn't result....could have come back to cinders.

Fortunately, I have a small battery charger and an extension cord which is plugged into the pedestal to keep the batteries up.

We may or may not head home tomorrow.  Our friends told us of a good mobile service they used for an inverter problem and it might be easier to have it worked on here rather than home.

 Any thoughts would be appreciated.

[Norm Green]

A few years ago I had a similar problem with power in the 2004 Thunder we had.  We also lost power to many of our outlets and was unable to use land power.  We were on our way back to the Northwest and stopped at Monaco to have them determine what the problem was.  After some investigation, they determined that it was a faulty power supply I was using for my computer.  I was told at the time by the tech. that they find this type of problem fairly often and he advised owners not to use them.   Fortunately our inverter was undamaged.

[Keith Cooper]

We had a similar problem in June of 2011. You might want to take a look at http://forum.bacrallies.com/m-1306544185/s-5/highlight-power+transfer+relay/#num5 good luck with the issue

[Dick Simonis]

Thanks for the replies.  A bit more investigation reveals the I did indeed have a fire in the overhead cabinet next to the TV.  The power strip is destroyed  in the area near the switch.  Wires and cables underneath are melted and fuzed into a mess to the point where the power strip is going to be tough to remove.  Fortunately the space is small and thanks to beaver, well sealed, so flames extinguished themselves with all the smoke.  Plus I see smoke damage just outside the door.

At this point, I'm reluctant to attempt supplied AC power to the coach until I have a better handle on what happened.  When daylight comes I'll take a look at the pedestal and see if it actually has power on all legs but I'm beginning to lean in the direction that the power strip problem is a result of something bigger.  Tripping a 50A circuit with a shorted power strip just is,t very reasonable and the coach 50 A breaker was not.

More going on here than meets the eye but I'm starting to lean towards a voltage supply problem....power surge?

Oh well, I managed to get the coffee pot working this morning using the extension cord so all is kinda OK.  Pat's been a trooper but I haven't yet told her that I'm thinking about staying here as there seems to be a better supply of good service centers than in Tucson.  I'm very concerned about all the wiring running behind the front cabinets and if than can be accessed without dropping said cabinets.....that would be major.

All in all, it could have been worse had the fire actually ignited the cabinets.

[Steve Huber Co-Admin]

Dick,
Based on what you've found, I'd be very reluctant to apply AC voltage as you don't know what other wires may have melted insulation and be close to causing a short while not yet tripping a breaker/fuse. Monday AM, you might want to call Tom at Massey's Diesel Service ((602) 233-1700). He's located on the west side of Phoenix (1417 S 59th Ave). Masseys RV repair used to be a Beaver and Country Coach service center and is very knowledgeable re these units. If he can't do it, he'll know who to go to. Feel free to use my name as a reference if you haven't been there before as I have him do all the service I can't do on my own. They get busy but Tom will usually get you in in an emergency. Tom is there by 7Am.
Good Luck! Steve

[Edward Buker]

Dick,

I do not think that anything external to your coach caused this failure. A dead short that pulls many amps of current will trip the fastest breaker in the chain given the current of all the breakers have been exceeded. I would have expected the lowest value 15 or 20 amp breaker to react more quickly but it is not always the case. If an external catastrophic high voltage spike caused your shorting fail it would have affected many more items in your coach and within the campground.

It is important before you take everything that is burned out that, you try and sort out what was the primary source of the electrical failure and what was secondary heat and fire damage. My suspicion is that you had a quick and catastophic short failure of the power strip. If it was plastic rather than metal it can then become the souce of the flame. Metal power strips are safer (but hard to find) given ithey will contain the heat from an internal short. Many power strips have a 15 amp resetable breaker built in and you may want that feature in your replacement power strip. There is also a relay involved in that area that kills he TV power with the ignition which could be a shorting source. Whatever the source it was clear that better than 50amps was pulled, at least momentarily, so the source of the short should hopefully be evident.

If the power strip was metal and you had powered AC wiring that went underneath it, that is also a potential shorting source if the wire insulation was compromised in some way.

I would change the lower current breaker that did not trip when it could have just as a precaution. I believe it is in the overhead area of the storage bay that is fed by the inverter. Once changed verify by turnng it on and off that it actualy controls the outlet that the power strip was plugged into and that you do not have some wiring error from the factory leaving an outlet unprotected. I am an advocate of flipping each AC breaker on and off once a year given they are mechanical devices and corrosion can be an issue. I have seen breakers that have frozen up and cannot be moved and therefor offer no protection. Just a good precaution for all of us.

So glad you are safe, like you say this could have been so much worse. Hope this helps.

Later Ed

[Dick Simonis]

Ed, thanks for the feedback.  Although the actual cause is still a bit mystifying it does appear the branch breaker did trip.  On this coach, there are 2 20A breakers on the inverter, the one for the galley did trip the other did not.  All the GFI's, 2 in the galley and one for the microwave also tripped.

It's puzzling how a short in a power strip could cause such massive damage including some (as of yet) unknown damage on the 50 A shore power circuit that render that whole circuit dead.  Maybe a problem in the transfer switch also...but on on the shore power side as the it does transfer source to the genny.

Can't figure out why the AC lighting works on inverter but not on Genny either.  As far as I can figure there are no branch breakers for distribution to lights or outlets other than the two on the inverter.  Plus, one shouldn't think the branch circuits care if the power is from SP or Gen set but that does appear to be the case.

With some circuits dead on the genny but not on the inverter also raises questions.

[Edward Buker]

I did a bit of research for 14AWG wire regarding the fusing current that would be required to develop a "hot wire fusing condition". It is 166amps for 10 seconds, 600amps for 1 second, 3300amps for 32ms. The tripping time rating on a 50 Amp breaker at 10X the current rating of 500 amps is about .01 seconds. While you would like none of this going on the specs would say that a hot wire condition should have been well protected. As the shorted area heated the resistance would have gone up until the breaker opened. The long and short of this is that the damage should be contained to the shorted area in the cabinet not taking into account any local damage by fire.

The breakers that get turned on and off a lot tend to have their current capacity diminished over time becoming more sensitive. They were really never mean't to be a switch but are used like that in campgrounds whenever we connect to them. This probably worked in your favor and may explaing why it acted first ....but don't forget to change the one on your coach that you expected to trip first anyway. Hope this helps set your mind a bit at ease.

Later Ed

[Edward Buker]

I think the short was a short and not a slight overcurrent condition that we think of kicking a breaker. There is a difference between 500 amps kicking a breaker and 25 amps which everything in the circuit can tolerate. The GFIs tripping would be normal given those protective devices are looking for stray current going where it is not expected to and you certainly had that here. Probably a short to ground and these are the fastest acting devices. The transfer switch would also have to handle the current overload and those are spring loaded surface contacts that I expect could have some damage. You can inspect those with the cover off and if slight residue and smooth contact surface is evident they can be burnished a bit with a very fine burnishing tool or file just enough to have the surfaces clean. They may be fine.

On my transfer switch the non powered default are the genny contacts. The relays are held closed by the AC from shore power when in normal shore power mode. The relays are released by the tranfer switch circuitry about 60 seconds after starting the genny if AC is provided by shore power. I think that is how mine works. If you can hear a buzzing from your transfer switch box when shore power is on what you are hearing is the vibration generated noise from the coils being powered with the shore AC which is holding them on against the spring tension.

There is also a tranfer switch in the inverter that is relay based that switches from shore to inverter so that may be a problem. All the coach AC lighting I believe utilizes the transfer switch within the inverter. Everying on that small bay breaker box is in series with the inverter based transfer switch. There may be a resetable AC button breaker on the inverter also that I would reset. It may only be involved with the internal inverter generated AC output but I am not sure of that.

This is the sequence I would try and bring things back up in. Unplug the coach from shore power. Cycle all the AC breakers on and off and reset all the GFI outlets in the coach. Cycle the breaker on the pedestal and measure for 120V on each leg. If that is O.K. then proceed, if not there is probably another campground breaker that has tripped that needs to be reset. Once that is set proceed. I would at this point opt to use a pigtail and power the next steps through a 30 amp circuit on the pedestal.  WIth the 20 amp kitchen breaker that tripped turned off in the bay, and the main rear coach breaker off, plug the coach back in and if all is well then turn on the main rear breaker in your rear panel. If anything trips then the fault has to be found within the coach before you can proceed. If all is well measure outlets on all the circuits and see if normal voltage is present. If it is then start the genny and see if it does a normal transfer. If you cannot get AC lighting to work as a pass through the inverter check to see if AC is being fed into the inverter and then not coming out. The main transfer switch that handles the shore power and genny transfer, powers the whole coach so if both sides of the main power panel has AC voltage that transfer switch is working at least as a pass through. As far as powering the last circuit up, that depends on an inspection as to how the wiring in the cabinet stands. If you could find an outlet on that circuit that comes before the problem one and disconnect the output 120v line that feeds the TV cabinet outlet then you could safely power up most of that circuit. All of this is activity that requires exposed panels or covers being removed where AC wiring is exposed and measurements are being taken requires some level of knowledge and safe practices. Only do what you are comfortable with. Hope this helps.

Later Ed

[Dick Simonis]

Ed, thanks for all the time you have taken to help walk me through this incident and I believe you may have nailed it.  While I still have not been able to remove the power strip in question....a bit hard to get to and it's still fused to the other wire in the bundle under it.  I have been reluctant to dig into it too far for fear of causing additional damage tried to separate all the wires.

You comments about the transfer switch in the inverter does explain why some circuits don't work on the genny as those are the ones that "pass through" the inverter.  Also, there is no power at the 50A pedestal receptacle and I will have the RV park check that this morning.

There is still a linger concern that there may be other damage caused by the large inrush current caused by the short.  It's certainly possible that other connections could have been compromised acting like a fusible link.  The inverter lights indicate that the charge is waiting for power so something is awry with the feed to that feature.

We decided to stay put in the RV park and I'm going to try to get a mobile service out today and look at the situation.  I've also decided to file an insurance claim seeing as how there was a fire involved.  Should be covered under out policy and it looks like a fair amount of rewiring will be necessary in the overhead compartments.

With the aid of three extension cords we're living quite well and even had TV and sat reception last night and coffee this morning.

Going forward, I won't put a replacement power strip in the same location but instead change the AC outlet in the TV compartment with a 4-gang receptacle and just plug every in directly.  My new TV installation on a swing arm makes that area easily accessible.  I definitely don't need a repeat performance.

[Edward Buker]

Dick,

Good luck with this and contacts should be the weak link here if power does not get restored. Contactors in the transfer switch, contacts in the inverter, contacts in the breakers that were directly involved with the current surge. The wire itself should have handled the overload given the typical 50amp breaker characteristics.

 It is always a help to us all to post how this turns out and anything that you learn in regards to what failed and what had to be repaired or replaced to get back online. Hopefully you will only have smooth sailing from here on out....

Later Ed

[David T. Richelderfer]

I see Camping World has Surge Protectors on sale - 50 amp regularly $450 now $292.50, 30 amp regularly $330 now $214.50.  A couple questions:

1: Are these worth anything?  Perhaps their weight in gold?
2: Do I need both the 50 amp and 30 amp?  Or can I use the 50 amp on a 30 amp receptacle and be protected (?)... with an adaptor in front, of course.
3. I have heard people like to steal these things when you leave your coach unattended.  How large a problem is this?

[Joel Weiss]

I see Camping World has Surge Protectors on sale - 50 amp regularly $450 now $292.50, 30 amp regularly $330 now $214.50.  A couple questions:

1: Are these worth anything?  Perhaps their weight in gold?
2: Do I need both the 50 amp and 30 amp?  Or can I use the 50 amp on a 30 amp receptacle and be protected (?)... with an adaptor in front, of course.
3. I have heard people like to steal these things when you leave your coach unattended.  How large a problem is this?

Yes, they are definitely worth it, but make sure you buy something that is more than just a surge suppressor.  Many folks on this forum use devices made by SurgeGuard and Progressive that will disconnect the MH from shore power if voltage is too high or too low or the pedestal is miswired.

A 50A unit will protect you irrespective of whether you are connected to 50A, 30A or 15A.

As for theft, we have a hardwired unit; it's not just a theft issue but simply one less thing to do when we hookup.  We had had a plug in unit on a previous MH and found we often didn't bother to get it out and use it.  Of course, it can't protect you if you don't use it.  

[Dick Simonis]

OK, Update as the RV tech just left.

First, Ed nailed the cause the power strip was absolute toast.  I should take a pic and post it but it was totally blown out and melted just behind the switch.

The transfer switch isn't passing shore power and needs to be replaced.

The inverter isn't passing power through the transfer circuit nor is it charging.  Needs to be replaced.

A CD shuttler for the Alpine dash stereo was overheated and needs to be replaced.

A bunch of wires and coax need to be sorted through, identified, and replaced/repaired.

Refrig wouldn't work on AC but that turned out to be the fuse.  Odd, since that is on a totally separate circuit.

The tech bypassed the transfer switch and inverter so we now have full power to the coach on shore power only.

After the tech left I hooked up power to the TV and etc by plugging everything into the 2 outlets in the TV cabinet and all is well but just found out the Bose system in inoperative.  Crap!!!  What we don't know is if some of the melted wires are for the Bose but it is on the same circuit as the other destroyed stuff.  It turns on and switches modes but no sound so I don't know what's going on here.  CD, Am/Fm, nothing.  Of course it could be the amp or the wires as I have not idea how the control head talks to the amp or where the wires run.

Tomorrow I should have the complete estimate as well as the time for parts, repairs, and etc.  Meanwhile we're still in lovely Goodyear.

[Dick Simonis]

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