elibedarn Report post Posted July 11, 2019 I connect to 50 amp shore power with no problems operating all appliances including 2 a/c units. When I operate the Onan generator only the forward a/c operates. When the rear a/c is switched on one of two things happen, the generator shuts down or the generator breaker snaps to off. No house breakers have ever shut off when using the generator nor when plugged in. In this 2002 Georgie Boy the electrical plug is either plugged into shore power or plugged into the generator. So I am looking at six foot of wiring, generator to plug. I have physically removed the plug and junction box from the generator and found nothing disconnected, nothing burnt, nothing shorted. Do any of you have a clue what may be happening? Such as a common Onan 5500 generator issue that may cause an internal short? Share this post Link to post Share on other sites
richard5933 Report post Posted July 11, 2019 Were you ever able to run both a/c units on the generator, or has it always had this issue? Share this post Link to post Share on other sites
manholt Report post Posted July 11, 2019 With both AC's off, turn on generator, then the bedroom AC...how many amps does it pull at spike when compressor kicks in? Turn it off & do the same with the front. Also, are both AC units the same size and what size are they? Share this post Link to post Share on other sites
dickandlois Report post Posted July 11, 2019 11 hours ago, elibedarn said: I connect to 50 amp shore power with no problems operating all appliances including 2 a/c units. When I operate the Onan generator only the forward a/c operates. When the rear a/c is switched on one of two things happen, the generator shuts down or the generator breaker snaps to off. No house breakers have ever shut off when using the generator nor when plugged in. In this 2002 Georgie Boy the electrical plug is either plugged into shore power or plugged into the generator. So I am looking at six foot of wiring, generator to plug. I have physically removed the plug and junction box from the generator and found nothing disconnected, nothing burnt, nothing shorted. Do any of you have a clue what may be happening? Such as a common Onan 5500 generator issue that may cause an internal short? As suggested in one of the reply's to your question. Start each roof AC and note the Current requirement of the rear and the front units. When the generator is running. You might want to make sure that all the electrical connections are tight at the generator, transfer switch and ac breaker panels. I see that your coach is wired for 50 amp shore power. That equals 100 amps of current load. You need to remember that when running the generator you have just a little more then 50 amps of current supplied from the generator. Not a lot of extra load capability beyond the 2 AC units. Link to the information covering the Onan 5500 series and the different configurations for LP and Gasoline. https://powersuite.cummins.com/PS5/PS5Content/SiteContent/en/Binary_Asset/pdf/Consumer/specsheets/a-1425.pdf Rich. Share this post Link to post Share on other sites
ianbullock Report post Posted July 11, 2019 Rich, I believe that the onan 5500 in question only puts out a max of 45.8 amps at 120 volts. So even less capacity. a-1425.pdf Share this post Link to post Share on other sites
bowtie Report post Posted July 11, 2019 Also check the 6' cable you mentioned. Is it heavy gauge, rated for more than 50 amps? Does it get hot when the AC is running and hotter when the second one is started? That 6' piece of cable can be a huge resistor that winds up limiting your available current. Try to verify all ground connections are clean and tight in the coach and the Onan. Share this post Link to post Share on other sites
kaypsmith Report post Posted July 11, 2019 Be sure to check the model # of your unit, according to the pdf supplied by Rich, there were only 2 models listed that uses two 30 amp breakers, but there is four listed that uses one 30 amp and one 20 amp. As stated above, you may be pulling too much load for one of the breakers and or the generator itself. There is no comparison of this generator to 50 amp shore power. Please let us know which model # yours is. Share this post Link to post Share on other sites
elibedarn Report post Posted July 13, 2019 No previous problems running both A/C units by generator. Breaker box never had issues in generator mode nor shore power. Of the two breakers on the generator only one throws. Junction box looks intact without marks of shorting. Pulled the plug for physical inspection finding no apparent issues. I think my best choice is to have Onan check the generator. I am not familar with RV repair facilities so am uncertain if they imploy quality electrical personal. I flew home leaving my unit 1500 miles from home therefore I can not run the requested test and I am uncertain if I have the equipment and knowledge. I have wired a few houses but wiring a new home has not prepared me for RV wiring. Certainly not generators. Thank you each for your suggestions. You are very kind to offer advise. I best leave this to an expert. I do feel maybe a wire jarred loose causing a short. Shore power elimated the plug, wiring, house breaker box, as well as all equipment inside the coach. Thanks again to you each. Share this post Link to post Share on other sites
elibedarn Report post Posted July 13, 2019 I flew home leaving my RV in Kansas City. Onan Cummings could not get to it while I was traveling. I am flying back 13 August. I feel a wire is loose shorting the red wire single leg. The generator breaker was thrown on that leg. The breaker felt soft when I reset it. In addition I accidentally felt a tingle with my hand when touching the generator platform. I may have a look for a bare wire at the generator connection. If I see nothing then Onan will need to repair it. I am guessing they would be better than an RV repair shop. In the multiple years of ownership I have not had an issue of running both A/C units with the generator. Thank you each for responding. You are very kind to offer advise. Share this post Link to post Share on other sites
kaypsmith Report post Posted July 13, 2019 Looking at the photo of the breaker box, I notice that there are four square D breakers, 1 fifty amp (don't know if that is a 50 amp 240volt, or 50 amp 120 volt which is rare to see a 120 volt), which is probably the main breaker for that box, if it is 120 volt it is not the feed for the box, 2 20 amp, then a dual 15 not with square d logo, then another 15 with square d logo. The dual one looks to have been added at a later time, it probably was changed out with a single handle square d breaker at the time that it was put into the box. Since you have owned the coach, have you added an appliance that required another 15 amp circuit? Also do you know what that dual breaker is feeding within the confines of the coach? You may or may not be aware that the dual handle breaker feeds 15 amps for a total of thirty amps off of just one leg of a 120 volt circuit, which means that one leg is capable of pulling 35 amps, while the other is capable of pulling 50 amps off of the other leg. So if there has been some added on then that might explain why a sudden change in the way things are happening. Just something else to think about when pondering what has happened. Share this post Link to post Share on other sites
rossboyer Report post Posted July 13, 2019 Reading the description of the box as being 120/240, I think the 50 amp is a double pole main breaker. The mess of wires below the breakers concerns me more. Possibly, this is the cause of ‘hot skin’ situation the OP mentioned. Share this post Link to post Share on other sites
dickandlois Report post Posted July 13, 2019 7 hours ago, rossboyer said: Reading the description of the box as being 120/240, I think the 50 amp is a double pole main breaker. The mess of wires below the breakers concerns me more. Possibly, this is the cause of ‘hot skin’ situation the OP mentioned. Ross, you are correct. The 50 amp breaker is for both L1 and L2 in this case and the 2 - 20 amp breakers are for the roof AC units. My gut feeling is that the 3 remaining circuit breakers are for other circuits, plus 2 other circuits are supplied from the inverter. That often supply power to the microwave(one circuit) and the second supplies power to the dining and entertainment circuits. Circuit barkers located in the output of the of the inverter. This is a link to the insulation manual for an Onan series generator. pages around 41 and 42 picture the wire runs between the shore power, generator and transfer switch. The tingling feeling sounds to me like you have lost the generator ground to chassis frame. The Wiring clearly show the common earth / chassis grounds being bounded together. file:///C:/Users/Data Base/Desktop/Onan Generator Install_8076_ky_spec_p_install_2015.pdf This drawing is for the 30 amp application, for a 50 amp application, the only difference is the addition of the L-2 circuit that parallels the L-1 circuit. When running both roof Ac's from the generator, There is a time delay relay frequently installed in the area of the main power panel. that allows time for the generator to settle down and the EMS system to monitor the load currents Rich. Share this post Link to post Share on other sites
kaypsmith Report post Posted July 13, 2019 10 hours ago, rossboyer said: Reading the description of the box as being 120/240, I think the 50 amp is a double pole main breaker This is my feeling also, I only added the other in case someone has done some funny wiring, that clumsy mess of wiring surely was not done in a factory, if it was their electrician should have been fired. All breaker boxes and the generator in an RV is supposed to be treated just like a sub-panel in a commercial or wired home, only the ground and neutral are only supposed to be bonded at the campground breaker instead of the main panel within an ordinary structure. The junction box pictured appears to be the junction between the generator and ATS, the OP is probably correct about a possible short occurring in this location. Share this post Link to post Share on other sites
richard5933 Report post Posted July 13, 2019 There is bare metal showing on the red wire going into the taped bundle. No doubt you have other messes in that box. Maybe some twist on wire connectors (a no-no in an RV). My first step would be those taped bundles and make sure that everything is properly secured with crimped connections. Under most circumstances, the neutral/ground bond should always be made at the source. For shore power, that's in the breaker panel feeding the pedestal. For generator use, that's inside the generator. And the chassis of the generator should be bonded to the chassis ground of the coach. Share this post Link to post Share on other sites
elibedarn Report post Posted July 15, 2019 Thank you each again for your input. No I have not changed the wiring nor added any appliances. At the junction box, under the black tape is a brass connector that screw clamps the wires together, followed by what appears to be insulation tape, covered by black electric tape. When I get back to my RV I will look at the Generator connection before taking it to Onan Cummings. With your excellent comments I have several things to check. Thank you each for taking time to respond. Much appreciated........................ Share this post Link to post Share on other sites
