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Shore Power Only Powering One Inverter
I’m currently parked at La Hacienda RV Resort on Lake Travis in
Austin, Texas. When I got back from the store today, half my power
suddenly shut off…It’s about 6 degrees from hell right now, so losing and A/C is
not an option.I cranked the generator to restore power and went to check out
the pole. The plug and cable leading into my coach was quite warm.
I killed the breaker on the pole and unplugged. One of the posts on my plug
was charred, so I thought maybe my plug arced for some reason. (That happened to me once before..)When I pulled the plug apart, everything was clean and
snug. No charred components and no loose
connections. So, I cleaned the charred
post and plugged it back in, thinking it was just a bad connection before. Nope… I’m still only getting shore power to
one inverter.The generator is powering both with no issues. I’ve called the park maintenance, but it’s
been an hour and they’re still not here.
Maybe there is an issue with the pole.
Any ideas?
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18 Replies
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Do you have a meter that you can use to check the plug at the post to see if it has the proper voltages? If it is just one leg, then I would think you are right that it is the power post.
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David…
You need to buy a surge protector and always use it at the pole… you plug it in to check your power before you plug the bus in… great prevention and if you do have a problem at the pole it will fry the protector instead of your bus… they cost around $150 I think but are cheap for the protection you get. It has lights on it to tell you how the incoming power is… I will email you the link to one.
I bet it is your power cord plug as we had the same problem with our Vantare… looked okay but after that post gets charred it wasn’t… you can pick up a new plug at Lowes… I always carry a spare plug with me.
Also do you have two manual switches to switch from shore power to generator? We did and it also had an “auto” position in the middle and maybe that has tripped… Ours did that when our cord was bad and I had to reset the actual inverter itself ( button on top of for that to work in the auto mode again although it worked with the generator. Switch it to inverter on the leg not working to check if that’s it. Don’t forget you have rest switches on the inverters in one of your bays too…. may be called emergency cut off but they are labeled Inverter #1 and Inverter #2.
I hope Mark is right about the post being the problem… would be your best bet for sure.
Good luck.
Cheers, Diane
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Thanks
to everyone trying to figure this out… We fixed it.It turns out, we were over amping the plug. The 50 amp plug is basically
2 legs of 25 amps. When you toggle between your inverters to see the
amperage, the total should not exceed 50, if you are plugged into a 50 amp
plug. This seems simple, and I should have realized this sooner (I’m
celebrating my 2nd anniversary in the coach), but that was the problem.In speaking with Tom (on call maintenance guy), he told me these coaches really
need a 60 or 75 amp plug, especially during a 100+ degree summer. My
problem was that I was treating it like my house. In other words, I would
plug into shore power and turn on every breaker I needed and a few that I
anticipated needing.Since
it’s so hot outside, the a/c units run constantly during the heat of the
day. The inverter that powers the mid
and rear units had too much load on it. That
inverter also has the instahot, washer and dryer, galley appliances (coffee pot
and i-Pod dock), and solan power outlets on it.
We washed a load of clothes twice this week, and that pulls a lot of
power. It was averaging 28 to 35 amps
for several hours per day on some days.
That’s too much for that leg of the plug… simple as that.
Your plug and power cord should handle 50 amp per leg. Your total available power should be 100 amps at 120 volts. That is what is available from shore power.
I am not suggesting you can draw that much power and not trip the shore power breaker, but those are the ratings.
I am surprised one side of the 50 amp outlet tripped the breaker because the breakers used are a pari of 50 amp ganged together with a metal connector between the two.
We all have to manage shore power. The typical coach will not have the ability to run everything electrical without tripping breakers. That is a given. If you have 3 or four A/Cs running along with a water pump, hot water heater, and numerous other loads all it would take to trip breakers would be for one of the A/C units to cycle on and the start up load on an already taxed breaker would be all it takes to trip it. I am not sure where you are getting the information that 50 amp service is limited to 25 amps per leg, but that is incorrect. However to be safe and avoid tripping shore power breakers limit the loads per leg to 40 amps and you will be OK. In the summer you might want to consider lowering the current draw on inverters so you can run your A/C units without phantom loads you cannot control loading the system.
The information of 25 amps per leg came from the campground guy because that is probably the way they have it wired. It is wrong but a lot of places put in a 50 amp plug and advertise 50 amp sites but do not provide 50 amps per leg but 40 or 50 amps total. I have seen campground poles with an old 30 amp plugs and an old 20 amp plug but a brand new 50 amp box beneath it. The new 50 amp box is being fed from the 30 amp plug on one side and the 20 amp plug on the other. Then to top it off the guy is the spot next to you is supposed to plug into the 30 amp which effectively taking you down to 20.
Davy
If what Davy says is true, if you run into a situation like that……….get out of there.
If you have a 50 amp receptacle, a 50 amp breaker and wiring for only 20 or 30 amps the wiring infrastructure is going up in smoke.
BTW, we have stayed at that RV park and it has not “cheated” on their shore power. I suspect the guy who made the statement about 25 amps did not understand how 50 amp power is a misnomer, and it should be called 100 amp.
In the heat of the summer it’s all about amps management. I don’t let mine get over 30 amps on each leg. I also disable the charge function on my inverters when plugging in at a campground when I know I’ll need as much AC as possible. That way the chargers remain on float. If you’ve driven any distance, the batteries are at full tilt from the alternator anyways.
The other problem is the campground folks will stick a meter on the plug and declare all is just peachy at 120 volts per leg. Try explaining to them as you load it with amps, it goes to 105 volts. They will then insist you have a problem with your coach. NOT
Jon is absolutely correct in that a 50 amp circuit has two 50 amp,
120 volt circuits. If a park tried to split a 20 amp and a 30 amp into a
50 amp, they were just fooling themselves, as most of the old boxes with the 20
and 30 amp were just a single line120 volt circuit. One other bit of
information on park plugins is that the circuit breakers that are installed
are just that…circuit breakers and not ‘switches’. They are not
designed to be turned on and off as a switch, thereby limiting their life
cycle. I used to buy them by the gross because a circuit breaker will
last about 500 cycles when used as a switch. With the 50 amp circuits,
one breaker would finally give out after about a year and you would receive
power on only one side. I had a separate tool pouch for electrical that
held my meters, klines, required screwdrivers and Allen wrenches for the lugs
along with extra breakers. Replacement pole plugs were in the tool bin. Having said that, always turn the breaker off before plugging or unplugging to reduce arcing.
One other bit of interesting information on RV Parks. The National
Electrical Code (NEC) requires that a row of no more than 10 spots be wired in Parallel.
That means that if every spot is occupied by coaches with a 30 amp hookup, then
one one leg of the 220 power is fully loaded and the other leg is having no
load. I met with the County electrical inspectors and showed them this
problem with the code when I rewired my park. I happened to get an actual
electrician rather than a political appointee and once I showed him, he fully
understood and allowed me to alternate the wiring between boxes and balance the
legs of the circuit. He inspected the work, and signed me off with a
green tag.The pole plugs last a long time, but eventually the spring compression of
the pole plug pressing on the blade on your coach plug become weak and allow
for arcing. This is usually not the
fault of the coach plug IF it is clean, smooth and in good shape. If the coach plug has been burned once, then
it is no longer smooth and has tiny high and low spots that will allow arcing and can
burn the next receptacle pole plug it is inserted into thereby heating and weaken the
spring tension of the pole plug. The
recommendation to install a new plug on your coach is a good one as a
pitted/burned plug blade will cause problems with every pole plug you use at a
park even though YOU may not notice it, the next person using the pole might. I also recommend that you wipe the blades of
your coach plug with a rag to remove any dirt or sand particles before plugging
into the pole receptacle, as dirt particles can also cause almost invisable arcing under heavy load. If you have to use a pry bar to remove your
coach plug from the receptacle, then you had a good connection 🙂‘OLD’ park owner Fred
David… Jon is correct… like I said in the email 50 amps per leg… and set your inverters to 45 amps incoming shore power that will keep you from tripping on the pole.(provided the pole is the way it should be).
Diane What an education! Thanks so much for your knowledge and experience.
The other problem is the campground folks will stick a meter on the plug and declare all is just peachy at 120 volts per leg. Try explaining to them as you load it with amps, it goes to 105 volts. They will then insist you have a problem with your coach. NOT
We just ran into this out in Bismarck, ND a few weeks ago, but they admitted the problem right away. We ended up running the generator that night and got a refund from the park for the issue. The owner said he had plans to re-do the line we were on yet this year as he knew from doing another one in the spring it would need it.I have seen what Tom described in numerous parks. Plug in and it is fine at 120v but load it up and it drops like a stone. I have a surge protector that displays not only voltage, but amp draw. It is very nice to be able to show this to the guy at the campround. They can’t deny it when you can show them it is on their end. Plus it give you good info for power management too.
We built shore power boxes under various trade names in our factory. We built tens of thousands of them annually.
Triple F is absolutely correct in what he says about how they are installed as well as the fact the breakers are not switches. I would add another comment………as part of normal maintenance RV parks should torque the screws that hold the wires into the breakers, bus bars and ground and neutral connections. Over time they loosen which in turn creates substantial problems.
It was not our role to advise RV parks how to install the shore power boxes because local code officials determine how they are to be installed and how to enforce the codes. But I can say we liked to see all boxes intalled using “home runs” rather than loop feeding multiple boxes on a circuit.
As coach owners we have to manage our electrical loads. We all learn how much we can run at one time and we learn to allow for loads we cannot control such as water pump, aux air compressor, HW heater, refrigerator and battery charging, all of which turn on or off without intervention. After a few 50 amp circuits are tripped we usually figure things out. But don’t always assume the issues are with the coach. It doesn’t take much for a loose connection in a shore power box to drop voltage, trip a breaker or even get things so hot the insulation on the shore power box wires melts.
I don’t let mine get over 30 amps on each leg.
How? I can barely keep it under 40 and still have spikes sometimes. Although I admit we need all A/C most of the time.
Your problem is trying to run 4 AC all the time. Unless and until you learn how to keep the coach cool with fewer AC units running you will continue to trip breakers.
I like a cool coach and Tom will agree when I say that because he is always whining about how cold it is in my coach, but I rarely need more than 2 units.
One huge contributor to heat in a Liberty coach is their use of BLACK shades for the front windshield. When the sun is shining on them they act like solar panels and transmit a lot of heat into the coach. Mine are a light tan color and it makes a big difference. I also close the shades on the sunny side of the coach. Unless you have all LED lights having a lot of lights on adds 50 watts of heat per light and 30 lights not only wipes out the cooling effect of one entire air conditioner, it sucks a lot of battery power the inverter has to make up for as a charger, adding to the electrical load.
Watch the current draw of the water pump, the air compressor, the HW heater. All of those turn on and off on demand and if you are at the limit and one or two kick on at the same time the shore power breaker will trip. The starting current draw on an AC unit can be 30 amps.
Karl,
Mine are Trace 4000’s and can be setup for any combination the user wants.
My Cruisairs start amps run 19.
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