| Author | Message | ||
| HappyCampersRus Rating: N/A |
I am replacing my genset with a Onan 6.5kw. This genset has four wires 1 ground, 1 neutral, and 2 power. Both power wires have 110 volts checked each with the neutral, 220 across both power wires, while the set is running. Do I need to tie (parallel) the two power wires in together?? I have heard you do this to balance the load on the windings. I am running 2 airs, Elect Fridge, 30 amp converter for 12volt stuff.Thanks | ||
| ChuckMC9 (Chucks)
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If you mean what it sounds like you mean, you'll let lots of smoke out if you do that. Smoke is best kept captive inside all working parts. | ||
| John MC9 Rating: N/A |
Happy? Try here: http://users3.ev1.net/~crossstitch/RVWiring/wiring.html | ||
| Richard Bowyer (Drivingmisslazy)
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no, no, no!!!! That is not the way you reconnect a genset. The windings need to be paralleled, but they also need to be in phase. Currently they are 180 degrees out of phase, and as Chuck says, you will let a whole lot of smoke out of the windings. In fact you will let it all out. The current configuration is known as a 240/120 volt output. You want to reconnect to a straight 120 volt output. I would strongly suggest you do some searching on the web for an Onan site that would have the technical manual. I am fairly certain I know what it is, but I would really like some confirmation. In general, most alternators have four main leads coming out of the windings labeled 1,2,3 and 4. Or something like that. However, as I recall, Onan has some different configuration and I do not want to advise you incorrectly. Richard | ||
| Richard Bowyer (Drivingmisslazy)
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The link that John posted is good if you want to wire your coach up as a 240/120 volt system.It does not show how to re-connect the genset internally for a straight 120 volt connection. Richard PS: That is a great link that John posted. | ||
| Jerry Liebler (Jerry_liebler)
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Happy, As it now sits it is wired to produce both 120 and 240 volts. If you don't have any 240 volt appliances it is better if the generator only produces 120 but at twice the current capacity. The 120 only works better at starting big loads like AC units. To get it to produce 120 only requires some internal rewiring. DO NOT just connect the two hots together. There should be an internal wiring diagram on the inside of a cover. Or get the manual. Regards Jerry 4107 1120 | ||
| John MC9 Rating: N/A |
Happy- Do -not- tie those two wires together. Use them as if you had two totally separate 120v circuits. On most RVs of older age, one of those "legs" would be connected to one air conditioner and possibly one or two outlets. The other "leg" would power the rest of the RV (and other air conditioner). The 50amp power cord is configured the same way; it is two "legs" of 120v and wired to your panel in the same manner. To be more exact, it is really a standard 220v supply to your circuit panel. With a properly wired 220v outlet, you can use a 220v appliance. Utilizing both "legs" at that one outlet, they are not "tied together" there; each 120v leg would be connected to it's own separate pin at that outlet, along with the neutral pin and ground pin. (as it shows at that link) Confused? Don't be. Think simple. Two 120v legs. I'm not too sure if Onan gives you a choice regarding rewiring the power leads for one 120v only. I had two Onans and they only provided the circuit as you described. I have a Honda that allows the change, but it's not a true 220v genset, while your Onan is. Remember: Think simple. | ||
| Stan Rating: N/A |
I have an Onan manual but it may not be for your particular unit. I would expect that they identify their wires the same in all models. The wires are identified as M1, M2, M3, and M4. These numbers should be printed on the wires. Your unit wired for 240/120 should have M2 and M3 joined together for the neutral with M1 and M4 as the two hots. To wire for 120 only: Join M1 and M3 to be the hot. Join M2 and M4 to be the neutral. This is a standard configuration so it should work. | ||
| John MC9 Rating: N/A |
Happy- There are some benefits of keeping it a two leg generator... There may be times that all you'll have for shorepower is a 30amp (or less) feed. With two legs to choose from out of the genset, you can fire up the genset to power the half that isn't being powered. Likewise, if some malfunction causes one of the genset breakers to trip, you'll be able to sit in 1/2 the bus air conditioned while you figure things out. With it all a single 120 feed, you won't have those choices. | ||
| Richard Bowyer (Drivingmisslazy)
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The configuration that Stan describes is what I was referring to and is the standard configuration om most alternators. I would recommend you reconnect in this manner and wire the bus for 120 volts only. I have to respectfully diasgree with John about the benefits of keeping it connected as a 240/120 volt circuit. If you are going to run the genset, then you do not need the shorepower and to say the least, it would be, in my opinion, a very dangerous and unconventional, to say the least, configuration. In conclusion I would suggest you rewire it as Stan outlined and then wire the coach as outlined in the link that John posted. Richard | ||
| John MC9 Rating: N/A |
With all respect, Richard.... And I certainly -do not- mean this to sound insulting: Nearly all older motorhomes and RVs were wired in that manner, and nearly all continue to be wired in that manner. Rewiring the Onan to supply 120v only (one "leg" only), is not a good idea. A few million commercially made motorhomes must prove some value to my comment... By the way... There is absolutely nothing "dangerous" or wrong with running the genset to power one air conditioning unit while the RV is on shorepower. It's not considered dangerous or wrong to use the commercially made 30 to 50 amp adapter they sell to use two 30 amp park connections to get the (split/two leg) 50 amp power you need to run both air conditioners when a 50 amp outlet is not provided. There is no difference between either situation. | ||
| Jerry Liebler (Jerry_liebler)
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John, There are good reasons for 120 volt only,even Onan recomends it, and NO valid reason for 120/240 wiring of the Onan. At 6.5KW it's about 54 amps of 120. If you run the genset while plugged into shore it's really simple ALL your power is coming from the genset. That's the way the automatic transfer switch is wired. If you tried to get power from both sources it would violate the NEC as ground neutral bonding would be occuring at both sources and that's a violation. You can keep the seperate legs in the pannel and when on shore use the cheater of two 30 amp circuits and still have the generator only produce 120. And I believe most of those older motor homes did just that, I know that one I had did. regards Jerry 4107 1120 | ||
| HappyCampersRus Rating: N/A |
John, When I wired the bus it was set up for one leg (120 volts only) as per the folks at the Camping World garage suggested. So without redoing the power panel, I have to install this Genset the way my old noisy one was. I see what your saying though, Not a bad idea. Thanks Stan & Richard, I will look again tomorrow for the wire #'s. Wished I had found this Website before the conversion!! Thanks Again. | ||
| John Jewett (Jayjay)
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Either way you do it, the total amperage available for consumption (a real misnomer, but commonly applied) is the same! The ONLY advantage to a straight 120V configuration is that you don't need to be mindful of balancing the amperage load between the two phases. Oh...like akrom says: legs is fur chikenz and wimmen. | ||
| John MC9 Rating: N/A |
Jerry- A simple question for you, hoping you can provide a simple answer that everyone can understand (including me)? The standard 50 amp shorepower line is actually two 120v legs. When it is connected to the panel, each of those legs are connected to only part of the wiring. That is, one leg supplying power to one air conditioner (and a couple of outlets), while the other leg feeds the other air conditioner (etc). In the standard RV generator setup, there are two legs of 120v from the genset, also feeding the panel in the same manner as the shorepower connection. The normal 30amp RV, when connected to a shorepower connection, will only power one air conditioner, while the other air conditioner remains connected to the generator. That is, and always has been the standard for 30 amp RVs. Why then, would there be an argument about using a two l20v leg generator in either a 30 or 50 amp scenario, when this has always been standard practice? Happy- Wiring the panel for a one leg 120v input puzzles me. How are you going to utilize the 50 amp service from the power pole, when that would be entering your coach as two 120v legs? And again, I don't want to appear argumentive; I'm not arguing for the sake of entertainment, but to understand something other than what I've been taught to be correct. | ||
| Jerry Liebler (Jerry_liebler)
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John, The generator, in this case a 6.5kw, has two 120 volt outputs each capable of 27 amps. One side of each of these windings is going to be connected to neutral, the other will go to the transfer switch and on to the pannel. If the windings have the same phase no 240 volts will be available in the pannel AND load sharring will occur, by transformer like action in the generator itself, this is the prefered connection. 50 amp shorepower is a 120/240 volt plug. If the coach's electrical system is wired for 120 volts only just one leg is used and it provides 50 amps of 120 volt power. If the coach is wired to use more than 50 amps of 120 volt power some must be taken from the other hot leg. That 50 amp shore cord can actually provide 100 amps of 120 volt current. Some RVs that came with a 30 amp shore cord do run the generator to power one leg while the shore powers the other BUT if it came with a 50 amp shore cord the loads are all on either the generator or on the shore, never power from both sources and it's only the 50 amp ones that can use the cheater of 2 30 amp inputs. Regards Jerry 4107 1120 | ||
| Tom Caffrey (Pvcces)
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John, according to the code, you must have one and only one point at one time where neutral and ground are tied together. This issue is called neutral-ground bonding. The campground will have it's neutral and ground tied together. Your generator will have its neutral and ground tied together. An inverter that has a complete transfer switch will tie it's neutral to ground anytime the inverter is inverting. This means that you are limited to one and only one power source at a time. All the grounds and the chassis of your coach should be connected together anytime a power source is connected to your coach. The circuitry must disconnect the neutral when it disconnects the hot wire from any source. Perhaps it is a little easier to see this way? This subject can lead to some difficult problems to solve, because compatibility can be hard to come by. I hope this helps. Tom Caffrey PD4106-2576 Suncatcher | ||
| Richard Bowyer (Drivingmisslazy)
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John, I have never explored the wiring on a commercial RV, but to the best of my knowledge it is prohibited by code to simultaneously provide two different power sources into the same distribution panel. Whether commercial RV's are built to code or not I do not know. Even if it were to code, the problem of separating neutral and ground from two sources could be a nightmare. And I still do not see any overall advantage. In my opinion if you are running the genset, then all AC power should be taken from it. But that is just my way. LOL Richard | ||
| John MC9 Rating: N/A |
Richard- I'm not sure about all the 50amp rvs, but in all the 30 amp rvs that I've been aware of, one leg of the genset's supply is permanently connected to one air conditioner, and the other leg to the rest.. When you unplug the shoreline from the rv genset socket, the genset remains connected to one air conditioner (It was from this electrical junction, that some rvrs connected a second shoreline, specifically to run the other air conditioner - let's not get into that now...please?). Now, that being said..... the circuits must be separate, since plugging the main shoreline into the shorepower socket has no effect to the air conditioner remaining on the genset's circuit.... If it was, by a neutral/ground bond, then it would be a "code violation" regardless if the genset was running or not. Did that make sense? I can't read and type at the same time if I am forced to think too.... I gave up smoking for that reason. | ||
| Jerry Liebler (Jerry_liebler)
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Richard & John, I believe you are both right, I had a stick and staple that was wired as John said (30 amp shore cord, only 1 AC on shore, could run second ac with generator). BUT it had a seperate distribution panel for the generator only circuits. BTW John, the generator was wired for 120 only. Regards Jerry 4107 1120 | ||
| Richard Bowyer (Drivingmisslazy)
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Well, I guess that kinda makes sense, especially if the genset is only large enough to run one A/C. Richard | ||
| John MC9 Rating: N/A |
Uhm... In both our Winnigarbagebago and Georgie-boy, the genset was an Onan 6.5 with two legs of 120, and ran both airs, the microwave, coffee pot and hair dryer at the same time. Not an argument, just a simple bit of info for digestion. It makes life interesting. I would keep the panel fed by "two legs", since that's essentially how the 50amp service enters. If the genset already is wired for "two legs", why not leave it alone? It'd make life 100% simpler. If he's going to run a 30amp system, well...... that's different, I suppose. (and he's said he wired it for 120) It was suggested that if "Happy" is going to use a 50 amp shoreline to carry the amperage needed, he would have to "turn back" (leave disconnected) one leg of that shoreline. Unfortunately, not all campgrounds supply the true 50/50 220 service at their 50amp panels. Many are carrying 20/30 or 30/30 and claim to be providing 50amp 120 service. That scenario would leave "Happy" not-so-happy. He would be getting the full service he wants, by splitting his panel and wiring it in the standard 220 way.....including the genset. Make sense? | ||
| Jerry Liebler (Jerry_liebler)
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John, If 240 volts are never needed there is No reason to have the generator deliver 240 volts. This is independent of how the panel's circuits are divided between the two lugs of the typical panel. With a 120 connected generator the transfer switch powers both lugs from the same source when on generator and from opositly phased 120 when on shore. In some cases it's desirable to have wildly unbalanced loads on the two 'legs'. For example, I have an inverter with 60 amps of pass through capaility so I have all the loads I'll ever power from the inverter on that side and only loads I'll never run off of the inverter on the other side. Only the electric element in my water heater is on the second leg, but it gets powered on shore and generator. Because my generator produces 63 amps of 120 this works well, I can get 50 amps out on the side through the inverter and 13 to the water heater. When I'm on 50 amp shore I get 50 amps out of the inverter side and 13 to the water heater. I do have to be a bit careful if I'm on a shore cord of less than 50 amps because the inverter will use battery energy to suplement the shore cord so I'll run out of battery charge if I use to much power. If I encounter one of those bogus 50 amp services I'll try to get my money back and be glad I can run all my AC on 30 amps with the inverter supplying starting surges from battery. Regards Jerry 4107 1120 | ||
| Richard Bowyer (Drivingmisslazy)
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I guess I have been fortunate, but I have never run into one of the bogus sites where the power was not as advertised. I know FF has mentioned this in the past but I have to assume that he was probably in a city park or something like that. I have stayed in campgrounds in all the continental 48 states and never experienced that. Not to say that it is not correct, but I suspect it is fairly rare and as people complain I assume it will slowly be corrected Richard | ||
| ChuckMC9 (Chucks)
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Richard, please don't get him started. ;) | ||
| Richard Bowyer (Drivingmisslazy)
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I think he is out on his boat somewhere. (hopefully with no internet service). LOL Richard | ||
| ChuckMC9 (Chucks)
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I meant JtNG! ;) | ||
| Dale L. Waller (Happycampersrus)
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Jerry is talking of how my bus is wired through the transfer switch. The way the switch is it only has one hot input on the genset side that is why I needed to "tie" the 120's together. I have hit a couple of older camps that lie about 50amp service. They try to tell you 1 20a & 1 30a make a 50a service. | ||
| John MC9 Rating: N/A |
Hey CHUCK... I'm sittin' right here, man. (Jeesh) | ||
| John MC9 Rating: N/A |
Richard, et al- I have a Honda EV6010 6kw 50amp genset. It's been factory wired for "two leg service" (there's two sets of 120v leads). One set is fused by a 20amp breaker, the other has a 30amp breaker. Both the Onans we had were like this also. If a campground models their power supply the same as what's been provided by the RV industry's standard, how can anyone fault them? 50 amp service in RVs were not being advertised as "220 volt service", or 100 amp service, nor were campgrounds advertising that they offered "220 volt service". All they claimed to offer was "50 amp service". They accomplished that, by wiring a shoreline and the power pole the same as we would wire 220v service. The difference, was only that 50 amp, not 100 amp, service to the RV was being offered... As long as all they're offering is 120v service and a total of 50amps service to the RV, why can't they provide it through a 20amp "leg" and a 30amp leg? I realize this topic has been beat to a pulp and I probably piss every electrical engineer and high end motorhome owner off with the redundant insistence of what's "real life", but hey.... that's the way it goes. It's out there; get over it. | ||
| Stan Rating: N/A |
John MC9: From reading the specs on your generator it would appear that you have a single 50 amp 120 winding on the generator. That is taken to a breaker box where it feeds two breakers (1 - 50 amp and 1 - 20 Amp). It would be most unusual to have windings of two different sizes on a generator. But in Japan anything is possible. You can make your wiring easier if you just take the 50 amp lead directly to you distribution panel and split it up there to suit your needs. Trying to balance the load on a panel with different sizes of supply would be tough. | ||
| Dale L. Waller (Happycampersrus)
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John, I see what you are saying. My shore cord is 10/4 two hot legs, but my transfer switch power panel only has Three lugs 1Hot, 1Neutral, and 1Ground. Thats why I needed to Phase both legs together. It really didn't make alot of sense to me, but hey if it works I ain't messing with it. It's probably not the proper why to wire it, but (knock on wood) it works. Sincerly thanks to you and all for your help. | ||
| John MC9 Rating: N/A |
Stan- The Honda EV6010 manual is here. Unless I'm getting more mentally decrepit than I've been, I'm seeing two windings with a separate breaker for each output. The Honda -can- be configured either 220 or 110, but since it will not put out 100amps, it really cannot be considered a true 220v genset (or not in my opinion). If it's used in a "110v" (just one hot lead) configuration, any appliance that will overload the circuit it's on can trip the genset breaker, leaving every appliance and outlet without power. In the 220v (two hot legs) configuration, there will always be power to one circuit or the other. Albeit, there is only 20 amps on one side and 30 amps on the other, but that's manageable through careful planning. | ||
| Brian Brown (Blue_velvet)
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Dale, your 10/4 shore cord is "goofy" in the RV world. That's like a residential 240v/30A dryer cord or something. 30A service utilizes a 10/3 cable. If all you're after is 30A service at the shore, that's only 3,600w, and you're probably able to make your cable work by binding the legs at the plug and at the switch. But if you want 50A shore service (and its 12,000w), you'll need a 6/4 cord and a transfer switch for the 4 wire service. Or just use the KISS plug-method described in a thread made a few days ago w/o a transfer switch. My converted bus was all messed up with code issues on the A/C electrical side when I bought it. Here's the lovely main disconnect: http://www.brownland.org/bus/elec/disconnect.jpg Like yours, it also had a 6.5kW Onan with a one-leg feed in it. I'm in the process of upgrading it to a 50A shore and two-leg service on my new(er) 6.5kW diesel genset. HTH, Brian Brown PD4106-1175 | ||
| Brian Brown (Blue_velvet)
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John, a "true" 220v genset in your book puts out 100A?! That's 24kW! Man oh man, you could run a modest-sized house off that puppy.  Even if you meant 100A @ 120v, that's still a big unit that'd probably run under-loaded most of the time in many rigs. Anyways, you're right about the Honda and its strange 30/20 breakers. It's one of the reasons I ruled it out as a genny upgrade in my bus. A single rooftop A/C and another appliance could trip the 20A leg pretty easily. A two-pole breaker (50-ish amps) would have been a better solution, IMHO. Maybe it can be rewired, I dunno. BB | ||
| John MC9 Rating: N/A |
Brian- Yeah, that was my point to all of this crap. What the engineers feel is the true situation, isn't the true situation in real life. As I said, the 6.5 Onans we had weren't much different. I don't remember if they were 20/30 or 30/30, but they were both a dual 120 service into the panel. Regardless, if a true 220 service at the power pole would supply 50 amps per side, then anything less should not be considered "true" 220v, 50 amp service. The genset does not deliver that. And most (older) parks do not deliver that, either. So therefore, it is unreasonable to assume that the rv should be wired for conventional 220v at 100 amp service, when it be very unlikely to be found at most parks. The power to expect, should be 120v at between 30 and 50 amps. And nothing less than a "two leg" circuit will deliver a 50 amp supply. Yikes! Are we there yet? | ||
| Brian Brown (Blue_velvet)
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It's actually 240v @ 50A service (12,000w) that we're talking about. Each leg (out of phase) is 50A @ 120v each (same 12,000w). If the parks you mention have a 50A breaker, and they are wired per NEC, then you should get 240v nominal across red & black, and 120v nominal across the white & black, and white & red, just like in your home. The parks you mention that don't "deliver" 50A service need to be spelled out specifically. Do they not deliver volts? I have heard of parks with low voltage, like in the 100/200 range, but even 100v/200v of 50A is still 10,000w... if your equipment can run on it, that is. They can't really "shortchange" you on amps the same way unless something is wired very wrong. If so, a quick call to the local building official might do more good than "conjecturing" about it on a forum. As for me, I believe it's quite reasonable to wire a bus conversion to use 50A/ 4 wire service when the "luxury" presents itself, and have provisions for 30A/ 3 wire when the need arises. I've even camped with 15A a few times this year, and it's enough to run a single A/C unit if I'm careful. And having the 50A/6GA shore cord would only help in a super-low amp/volt situation because you're reducing your voltage drop to almost nothing. I've also learned that bringing along some generic GE & Square-D breakers, a 30A receptacle and box, and a spool of 10/3 can make sleeping in the kin-folks' driveway a much more comfortable experience, as well. BB | ||
| Stan Rating: N/A |
JohnMC9: I don't know what to believe on your Honda EV6010. The spec sheet in the attached link show it to be 120 volt only. The link to the manual that you posted shows how to connect it for either 120 or 240. If the windings are in fact only rated for 20 amps and 30 amps then when it is connected for 240 volts (both windings in series) then you are limited to the current rating of the smaller winding. Your 6000w genset is then only 4800w. It is also possible that both windings are 30 amp but the engine isn't big enough. It is only 12.2 HP and Onan uses 14 HP on a 4000w generator. I would suggest that you clarify all this with Honda before you install the generator. Richard is the resident expert on generators and he may have some ideas. http://www.hondapowerequipment.com/ModelDetail.asp?ModelName=EV6010 | ||
| John MC9 Rating: N/A |
Brian- What wuz I thinkin'...? (yeah, I read that quote again and it's a tough read) What I was trying to say, was that there have been debates and downright arguments over what constitutes "true" 220/240 power and what isn't "true" 220/240 50 amp power, and what is commonly supplied at campgrounds. In that sense, it wouldn't be prudent -to expect -50 amps to be found on only one side (leg) of a "50 amp" outlet at all campground power poles, since that isn't what we can expect to find on one leg of any of the most common gensets. Or more simply - Wiring the breaker panel for 120v (one 120v leg/feed as "happy" is doing), more than likely will not provide enough power to run all his appliances at the vast majority of parks that claim to provide 50 amps service. Hell, I ain't no engin-ear and I have no professional training.. But I do think I know what is and what isn't... maybe I'm just not getting the words out right.. But I would wire my panel as if I had 220/240 power to it. My appliances and circuits would be split across the two "legs" (half on one; half on the other). And as far as I've noted in every RV I've looked at, that's the way the commercial outfits do it. Your answer to Dale was more in line with what I'm trying to get across. | ||
| John MC9 Rating: N/A |
Stan- Thanks for sharing my confusion. There's not too many people that make me feel like I've got any sanity left... That aside... I'll have to dig through my files today and locate the documentation for the Onans we've had. If I remember right (I've been having fits of C.R.S. lately), they had two breakers rated at about the same as this Honda. I never assumed either of the Onans to be "220/240" gensets. They did provide a total of 50 amps, enough to power everything electrical we had, at once. We did manage to overload one circuit occasionally, and had to reset the one breaker at the genset. The "other leg" always remained powering the rest of the RV. Actually, that was the basis of my reply to "Happy"; wire the panel for "two leg" (220/240) service, use a 50amp shoreline, and leave the generator providing power across the four wire (two leg) setup. I usually know what I'm trying to say, but can't manage to get it out of my fingers. | ||
| David (Davidinwilmnc)
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Stan, even if one breaker is 20 amp and one is 30 amp, the EV6010 can still deliver 6000 watts. (240 x 20) + (120 x 10) = 4800. It's just that the legs won't both support 30 amps. I've looked at several motorhomes in the past that were wired for generators like this. The front A/C and other elec. items were wired for the 30 amp leg and the rear A/C was wired for the 20 amp leg. There was a big switch outside in the utility panel that would select which A/C was connected to the 30 amp power cord. There's also another good reason (for me) to wire for 120/240. I'm running my bus from the elec panel in my workshop. It's only rated for 30 amps (240 volts). If I had my bus wired for 120 volt service, I would have a maximum of 30 amps (3600 watts) available to me. As it is, I have 7200 watts available. The same is true of parks that have 50 amp receptacles connected to 2 30 amp services (or a 20 and a 30). Of course, the bus can be wired 120/240 and the gen 120. | ||
| Dale L. Waller (Happycampersrus)
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John I'm reading your fingers correctly. I think this winter I will go with Brian's idea and just redo the wiring for a 2 leg set up on the plug method. My breaker box is already divided up half and half 2 Legs, so thats not a problem just need to redo my transfer that way. Then add a bigger shore line. Brian, were did you get that big of a cord?? Do you think I need that big all we have is 2 airs, 1 fridge, Small microwave, and 1 19" tv? We are leaving today for a local campground, So won't be able to respond till Saturday. Thanks Dale | ||
| Richard Bowyer (Drivingmisslazy)
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Someone posted a wiring diagram of an Onan a few weeks ago, and as I recall it had two windings, one connected to a 20 amp breaker and one connected to a 30 amp breaker (6 kW). Also these windings were out of phase so there would have been 240 volts across them. However, if you tried to connect them in parallel for 120 volts only you would have been limited to 40 amps total 4.8 kW). This is what I would consider a bastardized configuration, designed especially for the RV market, and an attempt to save money in the manufacturing process, thereby reducing somewhat the sales price of the unit for competition purposes. Otherwise, all single phase generators (alternators) on the marked are comprised of two identical windings to the best of my knowledge. For example, a 12 kW unit would have two windings, each rated for 120 volts at 50 amps. If these windings are connected in parallel (L1 to L3 and L2 to L4) then the output would be the combined AMPERAGE of the windings or 100 amps at 120 volts. Output to be taken from L1 and L2. If the windings were to be connected in series (L2 to L3) then the output would be the combined VOLTAGE of the windings or 240 volts at 50 amps. Output to be taken from L1 and L4 (240 volts) at 50 amps (12 kW). Or from L1 to L2-L3 and from L4 to L2-L3 for two 120 volt circuits at 50 amps each (12kW). Richard P.S. I ain’t no engine-ear, just had a lifetime of experience. | ||
| Richard Bowyer (Drivingmisslazy)
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David, you are correct as long as you leave the connections for 240/120. The problem would come in if you tried to rewire for 120 volts only. With the two windings in parallel, the maximum current you could pull would be 40 amps without overloading one winding. I agree also that you should leave the wiring as 240/120. When you are running on the genset with 120 volt output, you would just feed the power to both legs of the panel. Richard | ||
| Brian Brown (Blue_velvet)
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Dale, whenever you read this, I hope you had a great time camping... it's what this hobby is really all about. Having a 50A service means you would never trip breakers or have to worry about when your A/C units cycle on and off. 30A service can typically run two A/C units, but will sometimes trip if they both need to start a compressor within a few seconds of each other. Plus, you're running a LOT of current on the conductors with a 30A one-leg service, and the cords can get very hot. The same two A/C units on a 50A 4/wire service moves half the current through the hot legs and almost zero on the neutral (called "balancing the phases"). And the wires are so much larger anyways. Plus, you have reserve current in spades for your next electrical upgrade(s). IF you shop around for a 6/4 cordset, you can save a lot of $ off retail. Mine came via UPS yesterday from the ePlace, $72 (+$16 shipping) for a 36' version with a plug on it and 4 wires on the other end to hardwire to a receptacle. After having used 30A cords exclusively, the 50A is freaking huge! Weighs at least twice as much. 50A extensions are about 4-5x the cost of 30A ones, so I'm going to try to get by with the roughly 32' of radius I'll get out of the new shore cable. I'll have about $150 and a few man-days in the upgrade from 30A to 50A, but *priceless* in the sense of peace-of-mind. HTH, Brian | ||
| Buswarrior (Buswarrior)
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Hello to those electrically inclined. Thanks for this fascinating thread! My question RE: the choice of wiring the generator for 110 or 220 is related to the generator's ability or lack there of to maintain acceptable voltages: How many generators out there are able to properly produce their rated voltage if they are loaded on one side when wired for 220? Would that same generator do a better job of keeping the voltage up if rewired to dedicated 110 duty from the 220? I've seen one leg drop all the way to 100 volts, tripping the presets in a Trace inverter. (I use 110/220 only to defend against the 12/24 120/240 confusion if there is a typo.) Thanks for your comments! happy coaching! buswarrior | ||
| R.C.Bishop
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Try Ron the Bus Nut....Got mine from him...good price, as with most stuff he has. FWIW... RCB '64 Crown Supercoach (hwc) | ||
| Jerry Liebler (Jerry_liebler)
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Buswarior, You have found and stated the reason the generator should be wired for 120 ONLY assuming there are no 240 volt loads in the bus. Some generators only sense and regulate one of the windings, If you load the other side and not the sensed side the voltage under load will be very poorly regulated. The shore cord can still be a 4 wire 50 amp and the panel can still be split and the transfer switch has 3 poles, but at the generator red and black are in phase and tied together. Regards Jerry 4107 1120 | ||
| John MC9 Rating: N/A |
Huh? "the generator should be wired for 120 ONLY assuming there are no 240 volt loads in the bus. Some generators only sense and regulate one of the windings, If you load the other side and not the sensed side the voltage under load will be very poorly regulated. " That's odd.... The typical genset that is using a "two leg" configuration (a 220v configuration), is providing 120v to each leg. Yet they somehow manage to run one or the other AC unit alone just dandy, even though each air conditioner is alone on each independent leg. In fact, as it's been on most of these RV systems, 1/2 the RV is on one leg and no problems are suffered if nothing is using power in the other half. Why the concern now? | ||
| Jerry Liebler (Jerry_liebler)
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John, All the RV generator manufacturers recommend 120v connection if there are no 240v loads. The new onan 7.5KW quiet diesel doesn't even have the capability of 240. Have you actually measured 240v (when on generator)in any of those typical motor homes? You'll probably find most if not all have the generator wired for 120 only. Two legs yes but in phase when on generator. Regards Jerry 4107 1120 | ||
| John MC9 Rating: N/A |
Jerry- "most if not all have the generator wired for 120 only. Two legs yes but in phase when on generator." Egads man. That's what I've been trying to say. It's not "220", it's two legs of 110. Been tryin' to tell people that for I don't know how many threads, but the engineers keep claiming it's 220v. And as I've suggested to "happy", keep the genset the way it was, wired as two legs of 110v. Yet..... every BS degree seems to desire calling it "220". The majority of campgrounds that provide "50 amp service", are really only providing exactly what the most common genset provides - two legs of 120v for a total of 50 amps. Man..... I feel like Don Quixote and the 50 amp windmill. | ||
| Brian Brown (Blue_velvet)
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Arggh!!! (insert sound of me pounding head against wall). DooD, Put your meter between the two hots at these campgrounds and you're going to get 240v. If you live in a house, do it there, too. They're wired the same. There's a total of 50A of 240v OR 100A of 120v (12,000w) you can draw out before tripping the breaker. It's called 240/120 service. Do you really think both legs "at the majority of campgrounds" are in phase? Why would they wire it this way?! Loading up the neutral with all that current, and all... Please please please test this at your local campground before you go on and on about the "majority of campgrounds" like it's some kind of conspiracy, probably because you don't understand how it works. OK, so you can wire your bus with separate subpanels to take a leg of hot from shore power, each at 120v, but once you tap the other hot leg on a single device... drum roll.. you get 240v! Many gensets can provide two legs of 120v out of phase to get the 240v, just like the power company does. But they can also be wired to push a "larger wave", in phase, for 120v-only service. Calming down, now, BB | ||
| Jerry Liebler (Jerry_liebler)
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Brian, & Stan, There is no need for a seperate sub panel, the bus should be wired with a conventional 120/240 panel. It maters not weather the two hots are in phase or out. But because there is only one neutral when the two legs are in phase neutral wire size will limit the current that can be drawn. The reason the shore connection uses the two legs out of phase is it reduces the transmission losses, the source impedance of the power company is very low so source regulation is good, even with unbalanced loads. However, when on the generator a much higher source impedance is present and neutral losses are much less significant. Connecting the two legs in phase on the generator improves overall regulation significantly where this is not the case on shore. Without 240 requirements in the bus the generator should be wired for 120 only (both legs in phase). Stan, I am a BSEE. I really understand this stuff and am trying to help others understand it too. Regards Jerry 4107 120 | ||
| John MC9 Rating: N/A |
Jerry- Ahh-hah: "Without 240 requirements in the bus the generator should be wired for 120 only (both legs in phase). " You oughta' teach this stuff. Your last post was worth saving. I think most of us ignoramuses know what's going on, we just can't 'splain it right and aren't familiar with the proper nomenclature. Brian- Easy son, no need for shock therapy. Everything's ok... (ZAP) | ||
| Stan Rating: N/A |
John: I think you will have to rewire your generator for 120 volts. According to the link you posted for the manual on an EV6010, it comes factor wired 240/120. | ||
| Richard Bowyer (Drivingmisslazy)
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Excellent posts Jerry. I can confirm from many years of practical experience and building literally thousands of gensets that the loads on the two legs of a 240/120 volt alternator should be kept within 20% to maintain a balanced output voltage. This is if you are utilizing a voltage regulator that is sensing 240 volts. Since the voltage regulators in the RV type units are (almost) always designed for 120 volt sensing then loading becomes even more critical. Especially a large load on the sensed winding will try and drop the output voltage down and the voltage regulator will try and make up for this. This action then increases the voltage on the un-sensed leg significantly. One other point that needs to be explored it the neutral current in a 240/120 volt distribution system. In a system like this, with the loads on each leg being equal, the neutral current is zero!! (except for higher harmonic currents which is a totally different subject and not applicable to this discussion). The only current flowing in the neutral is the unbalanced current between the two legs. If there is 30 amps in one leg and 20 amps in the other, the neutral current will be the difference, or 10 amps. That is why the code allows the neutral to be sized smaller than the load conductors. Richard | ||
| Jerry Liebler (Jerry_liebler)
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All, Thank you for the kind words. Richard does bring up a good point about neutral currents. With the generator's windings in phase there is no neutral current cancelation, meaning that the wires and transfer switch must have neutral conductors equal to the hots for both windings. In other words if you've got a 12KW genset it'll need to have 2 #6 neutrals to the panel and the contactor in the transfer switch that switches the neutral needs to be capable of 100 amps. For the 7.5KW case a #6 neutral and 2 #8 hots , or all 3 #6 as I did. I also used 2 three pole 50 amp contactors on the generator side of my ATS with two paralleled poles switching each of the 3 lines to the panel. In other words I have 4 poles connected to hot and 2 to neutral on the generator. Regards Jerry 4107 1120 |