Hi Folks-
This has not happened often. The last time it happened the breaker was the last thing we checked and we ran the house batteries down to nothing. Tonight while making dinner the Charger breaker tripped under the bed. Electric grill, Microwave and AC Aquahot were on as well as some lights and the TV. We are plugged into a 50 amp pedestal. This has occurred before but I did not link the three high watt usage devices to the breaker tripping until tonight. Can any of you electrical people share with me what occurred? I presume we were using more amps than were available but why did the Charger Breaker trip? I know - Energy Management. :-[ Still learning.
Thanks in advance for your comments.
It may only be that the breaker that tripped is weak and needs to be replaced.Gam
Will have to make some assumptions on this, as there is some variation in both chargers and in wiring.
Assuming that the breaker that tripped is the breaker in the main breaker panel that supplies your INVERTER/charger (all that assumed), the explanation is as you said-- your total draw exceeded the breaker's rating.
The breaker supplies 120 VAC to the inverter/charger. The inverter/charger either has a built in transfer switch (often called pass through) or you have a separate ATS (Automatic Transfer Switch). If the breaker supplying 120 VAC trips, then the inverter automatically switches from passing through the shore power to supplying those circuits downstream of the inverter by "inverting" from the battery. Again, large 120 VAC loads supplied by the inverter will discharge the battery bank rather quickly.
If this is not how your coach is set up, let us know and we can go from there.
Thanks Gam and Brett.
The breaker that tripped is the breaker in the main breaker panel under the bed mounted on the platform.
We have a Magnum 2820 INVERTER/charger and 2 Automatic transfer switches. One under the bed and the other is in the basement.
Sooooo...Because I am attempting to draw more amps than the breaker is rated for, it trips?
Yes.
And, if the inverter is rated for more amps/watts than is the breaker, it may be able to supply those heavy loads, but will certainly take a lot out of the batteries.
What is the amp rating of the breaker? Have you added up the amp draw of the various loads you were running? Be sure to include some for the inverter/charger charging the batteries unless you have been on shore power for a couple of hours (so charge rate will have diminished).
BTW, many inverter chargers allow you to limit the amps used for charging the batteries to leave more amps to power other things in the coach. I know on the Xantrex products it is call "power share" and is programmable.
Brett the breaker is 20 amps. Our Magnum is rated at 2800 watts. The Prosine we replaced was rated at 2000 watts.
Aquahot - 1500 watts, Microwave - 1100 watts, Electric grill - 1500 watts, then some watts for lights and TV. We have been plugged in for days.
Soooo.. all incoming 50 amps is going through a 20 amp breaker and into the INVERTER/charger?
I do not know if the Magnum has Power Share. I will find out but since we have been plugged in the draw should be minimal.
Brett - How did you learn this stuff? What book should I get to read about how this stuff works in this practical application??
With the microwave and the grill you were pulling roughly 25 amps plus whatever the inverter was pulling to charge the batteries, so this would trip the 20 amp breaker.
No, only power to those circuits that can be powered by the inverter. Said another way, only those 120 VAC circuits that still work with shore power disconnected and generator off. I would be surprised if aqua-hot, roof A/C's, etc went through the inverter.
Learn by a lifetime of doing it. Worked my way through school turning wrenches on VW's, then did all the work on my off shore sailboats, now RV's.
I guess I am apprenticing now. Some day when I grow up I might know how this stuff works. Thanks for the help. :D
"Learn by a lifetime of doing it." That's the best way. Of course, it helps if there is someone there to stop me before I make a stupid mistake. One example: when I was in high school we finished the basement. One of the smaller parts in that project was to put in three-way switches at the top and bottom of the stairs. We got the new switch installed and were connecting the wires at the old switch when sparks started flying. Dad turned to me and said "I thought you took out the fuse." I replied "I thought YOU took it out." We both went downstairs and took out the fuse. Fortunately neither one of us was hurt, but since that time I always disconnect the power as far up line as I can before I do anything.
I usually work on a live circuit, it keeps me focused... ;)
I knew an old electrician once who checked for voltage by touching with his fingers...
If I could just master these computers. The software just kills me. I still have not gotten the retarder temp to work on my vmspc. My wife has to rescue me all the time. If computers only needed large wrenches and hammers, maybe I would be more successful.
Peter,
When I was in the Navy I worked on A7-E Coursair radars. We would test to see if it was transmitting by standing next to it while sweeping and putting our hand in front of it to see if we felt the heat on our hand. Crazy huh.
Mark
We have the same inverter (Magnum MS2812) and the same problem (breaker 8 - charger trips, kills all the inverter pass through circuits). Ridiculous, the inverter has 7200 watts pass through capability, should not be controlled by a 20 amp breaker. The pass through circuits are supposed to be controlled by the 50amp main on the inverter sub-panel.
Talked to James Triana, said he couldn't help much as he isn't familiar with the Magnum inverters, they don't use them. He thought it sounded as if the secondary transfer switch had been bypassed. He did send me the appropriate schematic, we had none with the coach.
The schematic shows circuit 8 (charger) goes from the main panel to the inverter to power the charger/converter. The pass through circuits go from the main panel to the secondary transfer switch. Struggling through the Magnum inverter manual, appears the Magnum has an internal transfer switch. Guess this would eliminate the need for the secondary transfer switch Foretravel originally installed. Seems this would also mean the pass through circuits should be wired directly from the main panel to the Magnum inverter (and circuit 8 charger eliminated).
MOT installed this inverter in 2012 when we bought the coach. Headed there next month for other repairs, will have them go through this. Will also talk to the folks at Magnum. If anyone has installed this inverter in a coach with two transfer switches, and solved the pass through problem, would like to hear how the wiring was done. Sounds like a major problem if a residential refer has been added to the inverter pass through circuits.
Mike,
Not sure I have a clear picture of how yours is wired, but many, many inverter/chargers have internal transfer switches.
And, it is common to wire from main breaker box breaker to inverter IN and inverter OUT to sub-panel powering only those things you want to be able to power from the inverter. The line from main breaker box also supplies the charger section of the inverter/charger.
What are you running that takes more than 20 amps total and is therefore tripping the 20 amp breaker. If batteries are deeply discharged (and therefore the charger section is taking a lot of amps), most inverter/chargers have a feature called "power save" or "power share" that allows you to restrict the amps the charger section uses. On ours, the default setting (amps to be able to be used by charger section) is 30 amps. I have it set to 10 amps, and there is a 5 amp setting. That will certainly allow you more power for your other items.
Brett
Brett
We were plugged in to 50amp shorepower for about two weeks before this happened. Can't see how the charger would have been pulling much but admit had not been checking. On Thanksgiving we had a turkey cooking in the convection oven, dressing baking in a toaster oven plugged in at the buffet in the kitchen. After about 45 minutes cooking, the coach interior lights dimmed, then came back up. Checked and found all circuits were working but we had been switched to inverting from the batteries. The batteries clearly couldn't maintain that much load for long so we switched to plan "b".
I've attached a pdf of the wiring as it came from the factory. Also a doc file of what's in our main breaker panel and the inverter sub-panel.
Thanks for your thoughts.
Yes, that clearly shows that there is a separate ATS. Wiring shows 6/2 from main breaker box to this secondary ATS and from the ATS onward. So, yes, the breaker in the main box can certainly be larger than 20 amps assuming the diagram does reflect what you have.
As always when working with electricity, least strong element dictates capacity.
Mike I am glad that you are dogging this down. Sounds just like our situation. We have been watching our power usage and making adjustments to avoid this situation. It is crazy to me that this is occuring but I have greater issues on which to work today. Also thank you for the attachments. I will copy and file in my U320 file.
Thanks again,
Scott
You might check the magnum inverter. Some of them had 2 inputs and 2 outputs. If they are wired together that could cause the inverter to pull more power than a 20 amp breaker could handle. If that is the case the charger circuit could go to one input and the other circuit breaker could go to the other input. However with a microwave on and a toaster oven on that would overload a 20 amp breaker.
I called Magnum. The tech verified the charger and inverter were both working. Referred me back to the chassis builder, had no idea how a two transfer switch system would work. Talked to James Triana at FOT. He sent me the appropriate pdf, said FOT doesn't use Magnum inverters, wasn't sure where to point me.
Went through the pdf of the inverter electric from FOT, tried various combinations of inverter, charger, and circuit 8 shore power on and off. Called James Triana back with results of my trials. He thought it sounded as if the secondary transfer switch has failed. This switch has two inputs, a 50amp 6g line from the main panel, and a 30amp 10g line from the inverter.If this switch failed and would pass 120v from the inverter, but not from the main panel, would explain everything.
I'm going to assume this is the problem, will post back to this thread if this solves the problem. Will start a new thread seeking help on the switch replacement.
Can't help with your secondary transfer switch replacement, but I moved the microwave circuit from the inverter output to its own breaker on the primary panel when we had our old Xantrex inverter charger. We never run the microwave off the batteries, and having it on its own circuit meant we didn't have to juggle toaster and microwave use on the Xantrex 30 amp pass through to the secondary panel.
We now have a Magnum, (the 2KW version MS-2012), and its internal transfer switch works fine, but our coach didn't come with a secondary external transfer switch.
Just checked the Magnum manual, and for MS2012 and MS2812, the maximum feeding breaker size for "single-in / single-out" configuration is 60 amps or the max the RV primary panel is wired for. The feeding breaker for ours is 50 amps. If you change the feed breaker to 50amps, you may solve your immediate problem. The max pass-through is 60 amps according to the manual, so the internal transfer switch should be fine.
Hi Dave - Hope all is well with you guys.
Based on the table copied from the PDF above our microwave is on a separate breaker on the Inverter sub panel and the 20 amp Battery charger is on the main panel. Am I correct to assume that all of the Inverter sub panel power comes from the 20 amp Battery charger breaker?
Inquiring minds whish to know. :-)
Electrical Panels
Mains
50
50
3. Refer, line monitor, vacuum, freezer 20
4. Rear roof AC 20
6. Aquahot 20
7. Hot water dispenser 20
8. Battery charger 20
9. Engine heater, line monitor 20
10. Front roof AC 20
11. Blank 20
12. Washer Dryer 20
14. Middle roof AC (option 4200) 20
Inverter sub panel
Main
50
1. Ice maker, TV, VCR, Sat, Bose, Dash, Bedroom 20
2. Microwave 20
5. Fan, stove, line monitor, TV, bath, kitchen 20
Morninghill - Good day. I have taken the liberty of sending your above attachement to Magnum requesting assistance re: Charger Breaker tripping.
Yes on ours, all the power for the inverter/charger (now Magnum) comes through the 50 amp breaker on the main panel. All of the sub panel is fed from the 120V output from the Magnum inverter/charger. So if we're running on inverter, the max is 30 amps@120V (for a short time...), and when on shore power, the transfer switch in the Magnum is passing up to 50 amps from our main panel, and the max combined power output from the sub panel is therefore 50 amps.
Sent wiring diagram to Magnum for their review and breaker assignment by box. Their Tech guy suggested I put a 30 Amp breaker in that circuit as the inverter/charger will use 18 amps at full charge rate and only leave 2 amps for pass through. He also noted: that I "have a bypass transfer switch on the output but he wasn't sure which position is priority". ???? Waiting for a call back to clarify.
Sent wiring diagram to Magnum for their review and breaker assignment by box. Their Tech guy suggested I put a 30 Amp breaker in that circuit as the inverter/charger will use 18 amps at full charge rate and only leave 2 amps for pass through. He also noted: that I "have a bypass transfer switch on the output but he wasn't sure which position is priority". ???? Waiting for a call back to clarify.
Update: After speaking with the Tech at Magnum and me explaining what has been happening with the breaker tripping, he feels that the (6/2G) wire from the Main Circuit Breaker Box and the Circuit #8 wire are in the incorrect position in the Switching Relay #2. In the current wiring all coach power would go through Circuit #8. He has suggested that I swap positions on the Swithcing Relay #2. He futrther suggested I get my multimeter and by measuring the inputs I should be able to determin the actual wiring. I believe he said that the inverter/converter will have the same reading both input and output whereas the input and output from the pedestal will be somewhat different.
So.......All of you electrical guys out there - Does this make sense to you? And if it does, I should be able to exchange input positions on the Switching Relay #2 and eliminate this tripping issue.
By the way re: Changing the breaker from a 20amp to 30 amp for Breaker #8. - Is not a good idea unless the (12/2G) wire from breaker #8 is increased to accept the load. Of course he said this before we started talking about which power leg goes into the Switching Relay #2 from the Main Circuit Breaker Box and inverter converter.
Scott,
Part of the answer will depend on actual location of the components. If that 6-2 wire from main breaker box to second ATS could be used to provide power IN to the inverter/charger, likely using a 30 amp breaker, then the inverter/charger's internal ATS could be used and remove the secondary ATS. The sub-panel could be wired from the inverter/charger 120 VAC output.
Bottom line, unless you will be running enough different appliances to exceed the inverter's capacity, I see no reason for a secondary ATS. If you might exceed the inverter's capacity, I would run heavier wire from main breaker box to inverter IN and use a 30 amp breaker. Then inverter OUT to ATS. But, make sure that the "favored" position for the secondary ATS is shore power!
Brett
Brett - Wouldn't it be easier/better to flip the wire position going into the ATS?
If you mean wire shore power as priority, yes, you can do that.
But, not sure I understand the reason for an additional ATS (second one in addition to the one built into your inverter/charger).
You should still use heavier wire and breaker to supply the inverter/charger (to feed the charger section-- you don't want to be within 2 amps of capacity) and verify with Magnum that they have no problem having 120 VAC in, but not supplying sub-panel from inverter unless shore power is off.
Brett - Good point.
So are you saying I could run 6/2G wire from the Main Breaker into inverter/converter power and take Inverter Output directly to Circuit Breaker Box #2. OR Leave wiring the way it is and just replace Breaker #8 with a 30amp and change Circuit #8 from 12/2G to 10/2G making sure that the 6/2G wire (Pedestal) be placed on the Primary?
Yes, either option would work.
But, having the extra ATS just adds one more item which can fail. The only reason for the second ATS is that you want to be able to run things powered by the sub-panel that exceed the capacity of the inverter and its internal transfer switch. If not, remove one piece of complexity.
Brett -
What you said is a mouth full. Don't know if I'm comfortable bypassing the #2 ATS. HMMMMMMMMMM.
I have sent and email to Magnum requesting input regarding bypassing Switching Relay #2.
Hi Scott
When I talked to James Triana at FOT he said that as originally wired, the secondary transfer switch gives shore power priority. With 50 amp to the secondary transfer switch, then to the inverter sub panel, you have plenty of power for the three 20 amp circuits on the inverter sub panel. Provides for those of us who might be using microwave, toaster, coffee maker, electric grill, etc when on shore power.
If the secondary transfer switch fails, it could block shore power but pass power from the inverter. James opines this could be what happened. If so, the inverter would still pass shore power from circuit 8 (charger) to the transfer switch, then to the inverter sub panel. This would leave you with a 20 amp circuit from the main panel feeding the three 20 amp circuits in the inverter sub panel. Easy to see how the breaker would trip.
In our coach both breaker panels and both transfer switches are under the bed. The inverter is about 20 ft forward. Replacing the secondary transfer switch requires removing the primary transfer switch and the surge arrester/ems and the secondary transfer switch, then reinstalling all three. Pulling new wire to and from the inverter would give me up to 60 amp pass through (inverter pass through limit) but that's a lot of wire and I'm no electrician. I don't see any attractive options.
Got a response for Magnum thea AM. Is as follows:
"You could do that but you will need to move the 6/2G wire from the main buss in the main panel to thirty amp breaker or wire the inverter for single in single out 60 amp and change the wire on the output of the inverter to 6/2G also. This is because the 6/2G there now is protected by a 50 amp breaker and all wire must be sized for that size overcurrent protection. FYI I would probably do this if it was my installation, one less failure point."
I will review the schematic and try to digest what he suggested. Will probably follow Brett's and Magnum's suggestion once I figgure out HOW to do it. ??? ???