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Car Forum / Driving, Maintenance, Tuning / RVs / September 2005Changing from 30 amp to 50 amp
My MH has a 30 amp shore connection, a 6.5 KW generator (50 amp output) and 2 roof a/c's. As it now stands, I can only run one a/c at a time. What is involved in changing the shore line to 50 amps and by-passing the a/c selector switch? Has anyone done this? What are the pros and cons of doing this? Howard > My MH has a 30 amp shore connection, a 6.5 KW generator (50 amp > output) and 2 roof a/c's. As it now stands, I can only run one a/c at [quoted text clipped - 3 lines] > > Howard I did not have an AC selector switch, but I did do the change from 30 to 50 amp. Figure at least 1 full day of work and between $400 and $600 depending on what type of ATS and main breaker box you have. http://www.bobhatch.com/electricStuff/30to50amp.htm Or you can do what Steve Wolf did here. http://www.wolfswords.com/motorhome/50_amp.html  Signature"Everyday I beat my own previous record for number of consecutive days I have stayed alive." http://www.bobhatch.com http://www.tdsrvresort.com Thanks Bob. I'm not sure if I can run both a/c's when only generating (even though it has the capacity). I just bought this MH (a '94 Land Yacht) and I'm still in the learning curve (first time diesel too). >> My MH has a 30 amp shore connection, a 6.5 KW generator (50 amp >> output) and 2 roof a/c's. As it now stands, I can only run one a/c at [quoted text clipped - 11 lines] >Or you can do what Steve Wolf did here. >http://www.wolfswords.com/motorhome/50_amp.html > Thanks Bob. I'm not sure if I can run both a/c's when only generating > (even though it has the capacity). I just bought this MH (a '94 Land > Yacht) and I'm still in the learning curve (first time diesel too). You most likely can. Best way to find out, start the generator and try, but it's a fair bet that it's set up to run both on generator. Signature"Everyday I beat my own previous record for number of consecutive days I have stayed alive." http://www.bobhatch.com http://www.tdsrvresort.com I'll go over the schematic this weekend and figure it out. My guess, though, is that because there is a SPDT switch that selects either front or rear a/c, even on generator it will only run one. I'll also have to see where the breakers are to determine whether each a/c is separately fused, otherwise, the modification will be more extensive. >> Thanks Bob. I'm not sure if I can run both a/c's when only generating >> (even though it has the capacity). I just bought this MH (a '94 Land >> Yacht) and I'm still in the learning curve (first time diesel too). >> >You most likely can. Best way to find out, start the generator and try, but >it's a fair bet that it's set up to run both on generator. > I'll go over the schematic this weekend and figure it out. My guess, > though, is that because there is a SPDT switch that selects either > front or rear a/c, even on generator it will only run one. I'll also > have to see where the breakers are to determine whether each a/c is > separately fused, otherwise, the modification will be more extensive. Unless yours is "radically" different from most, the generator will have 2 breakers. One 30 amp, and one 20 amp. You should have one 20 amp breaker for the AC on the main box in the MH. When on shore power, this breaker feeds the SPDT switch, and you can choose front or rear AC. Most ATS (automatic transfer switches) are set to Generator as first select, meaning that if you're plugged into shore power, and then start the generator, the ATS will route your power from the generator. When you start the generator the 30 amp part of the genset feeds the main in the MH, the 20 amp feeds the rear AC, therefore both should work in generator. It will be a fair sized job to convert your system, and unless you are pretty good at electric stuff, get help. Signature"Everyday I beat my own previous record for number of consecutive days I have stayed alive." http://www.bobhatch.com http://www.tdsrvresort.com > > My MH has a 30 amp shore connection, a 6.5 KW generator (50 amp > > output) and 2 roof a/c's. As it now stands, I can only run one a/c at [quoted text clipped - 11 lines] > Or you can do what Steve Wolf did here. > http://www.wolfswords.com/motorhome/50_amp.html Bob, So after your change you can ONLY run on full 50amp 2-leg service even though you're not using but 120vt? Wow, that would rule out about 90 to 95 percent of the camp sites I've stayed at in the last two years-- probably less than 1/3 of the campgrounds in this area even have 50amp service at all and of those that do only a limited number of their sites may have it. The others all have 30/20 posts. I'm talking mainly State park and Corp of Eng but the few private ones I've stayed at are similar. I noticed at the last COE park each post now has a big label on the cover stating that you could only pull 24amps max from any combination of the outlets and that any attempt to exceed that thru home built or commercially built "devices" would be a violation of the rules. It seems to me that Steve Wolf's answer is the more flexable choice-- take advantage of the 50 if it's available but not restrict youself to 50 only. You could even do it more elaborately if you wanted to and allow for more circuits than just the rear air to be switched (either using his plug method or DPDT switches or relays). Which reminds me of a question I think I'll ask here. I just looked at a DP that had basement AC. Are those basement AC units running on one 120 leg or do they need the full 240 two-leg circuit like a house unit? I forgot to ask the salesman about that--a 240vt AC would rule out the entire coach for me for this area. SignatureJud Dallas TX USA > Bob, > > So after your change you can ONLY run on full 50amp 2-leg service even > though you're not using but 120vt? Well, a fine example of a person who does not understand how the systems work, and what a 30 amp to 50 amp dog bone adapter does, or how it works. Wow, that would rule out about 90 > to 95 percent of the camp sites I've stayed at in the last two years-- > probably less than 1/3 of the campgrounds in this area even have 50amp > service at all and of those that do only a limited number of their > sites may have it. The others all have 30/20 posts. And with the proper adapters in the end of the shore power plug, I can use one more than you can. I can use 50 amp, 30 amp, and 20 amp. I'm talking > mainly State park and Corp of Eng but the few private ones I've > stayed at are similar. I noticed at the last COE park each post now > has a big label on the cover stating that you could only pull 24amps > max from any combination of the outlets and that any attempt to > exceed that thru home built or commercially built "devices" would be > a violation of the rules. So how would that effect me? > It seems to me that Steve Wolf's answer is the more flexable choice-- > take advantage of the 50 if it's available but not restrict youself to > 50 only. You could even do it more elaborately if you wanted to and > allow for more circuits than just the rear air to be switched (either > using his plug method or DPDT switches or relays). Well, it would seem that way if you don't understand the way RV AC electric systems work. I do understand it, and know better than what you pose in the above statement. > Which reminds me of a question I think I'll ask here. I just looked > at a DP that had basement AC. Are those basement AC units running on > one 120 leg or do they need the full 240 two-leg circuit like a house > unit? I forgot to ask the salesman about that--a 240vt AC would rule > out the entire coach for me for this area. 120 volt if only 30 amp is available. When 50 amp 120/240 is available the cooling functions of the AC improve, I think it has to do with a second compressor. Signature"Everyday I beat my own previous record for number of consecutive days I have stayed alive." http://www.bobhatch.com http://www.tdsrvresort.com > > So after your change you can ONLY run on full 50amp 2-leg service even > > though you're not using but 120vt? > > Well, a fine example of a person who does not understand how the systems > work, and what a 30 amp to 50 amp dog bone adapter does, or how it works. Even if I don't "understand" that's no reason for you to reply like that to a valid question (this isn't RORT). Actually I "do" understand how the "systems" work but perhaps I don't understand how the 30amp to 50amp adapter works. I assumed it converted 50amp to 30amps by DROPPING ONE LEG in which case you would LOOSE every device connected to that leg in the breaker box (in which case Steve's answer is the more flexable by allowing one to choose which devices aren't needed). If it COMBINES the hot legs in the 50amp cable and attaches both to the hot in the 30amp outlet then yes and I withdraw my objections (and only hope that the few RV's with real 240vt equipment never tries to use one of those!!). SignatureJudH Dallas TX USA >> > So after your change you can ONLY run on full 50amp 2-leg service even >> > though you're not using but 120vt? [quoted text clipped - 14 lines] > objections (and only hope that the few RV's with real 240vt equipment > never tries to use one of those!!). Actually, Jud, the 30-to-50 feeds 120V from the single-circuit 30A to *both* 120V legs of the 50A *single-phase* 240V. Single-phase 240V is made up of 2 120V legs [plus a "common" and a "ground" to name the other 2 wires]. This, BTW, is also what is used by most residential 240V equipment. A 50A-to-30A adapter, on the other hand, simply feeds the 30A plug from 1 of the original 2 120V circuits. It's my understanding that a number of RV manufacturers have facilitated a 30A-to-50A "upgrade" by installing 50A breaker boxes with a shunt between the two legs. Removal of the shunt with the installation of the additional wiring and plug(s) completes the project. On another note: how's the weather in Dallas this AM? > >> > So after your change you can ONLY run on full 50amp 2-leg service even > >> > though you're not using but 120vt? [quoted text clipped - 17 lines] > Actually, Jud, the 30-to-50 feeds 120V from the single-circuit 30A to *both* > 120V legs of the 50A *single-phase* 240V. Yeah, kinda guessed that after Bob bit my head off. I had assumed it simply dropped one leg. > Single-phase 240V is made up of 2 120V legs [plus a "common" and a "ground" > to name the other 2 wires]. This, BTW, is also what is used by most > residential 240V equipment. Right. So someone with true 240vt equipment using a 30-to-50 adapter would be connecting both circuits to the "same" 30amp hot wire. It certainly wouldn't operate but guess it wouldn't be a problem either-- current wouldn't flow at all right? > A 50A-to-30A adapter, on the other hand, simply feeds the 30A plug from 1 of > the original 2 120V circuits. [quoted text clipped - 5 lines] > > On another note: how's the weather in Dallas this AM? Overcast, 85deg, light breezes, NO rain. And no rain expected either. It totally missed us but the folks in east Tx are getting drowned. SignatureJud Dallas TX USA > > >> > So after your change you can ONLY run on full 50amp 2-leg service even > > >> > though you're not using but 120vt? [quoted text clipped - 40 lines] > > the two legs. Removal of the shunt with the installation of the additional > > wiring and plug(s) completes the project. We have a 5er with 50 amp shore power connection and 27,000 btu basement heat pump. When we use a "dog bone" to plug into a 30 amp shore power box, we flip a switch inside from the 50 amp position to the 30 amp position. One of the things this does is to remove the second stage of our heat pump from the power source. At this point we only have 13,500 btu of heating or cooling. On the left side of our rig near the rear is a small door. Inside is breaker and underneath the side skirt is a plug. We can run a cord from that plug to any 15 or 20 amp shore power and run the second stage of our heat pump from that source. Ron > Right. So someone with true 240vt equipment using a 30-to-50 adapter > would be connecting both circuits to the "same" 30amp hot wire. It > certainly wouldn't operate but guess it wouldn't be a problem either-- > current wouldn't flow at all right? Any attempt to draw more than 15A @ 240V would trip the pole's breaker BUT, if the equipment would run on 15A, it'd run. There is, however, a distinct shortage of 240V equipment in an RV. <G> >> Right. So someone with true 240vt equipment using a 30-to-50 adapter >> would be connecting both circuits to the "same" 30amp hot wire. It [quoted text clipped - 5 lines] > > There is, however, a distinct shortage of 240V equipment in an RV. <G> There might be some, somewhere. But everything I've seen so far is 120 volt, just lots of it. The difference is, when we're on 30 amp, we can run 2 AC's, the computers, TV and Tivo, maybe the coffee pot. Max. If Mary wants to use the microwave, she has to turn of the AC's. She feels "limited" in what she can use. With 50 amp service, she can have both AC's going, both coffee pots, electric WH, toaster, TV's, Tivo, computers, electric skillet, and she can use the microwave, all at the same time. There is a limit, but we haven't found it yet. Like I said to Jud, we came close to putting in an electric stove top, but didn't want to be restricted that much for cooking, and it was 120 volt. Just because 240 is available, doesn't mean it must be used. Signature"Everyday I beat my own previous record for number of consecutive days I have stayed alive." http://www.bobhatch.com http://www.tdsrvresort.com >There might be some, somewhere. But everything I've seen so far is 120 volt, >just lots of it. The difference is, when we're on 30 amp, we can run 2 AC's, >the computers, TV and Tivo, maybe the coffee pot. Hi Bob, I hope you aren't putting an undue load on the acs running two on 30 amp. From what I hear they will run, but it's shortening their life straining them like that. That's why you see one ac on rigs with 30 amp service and two on rigs with 50 amp service. Hunter -- http://members.aol.com/hhamp5246/roadtrip2005.htm Life's journey is not to arrive at the grave safely in a well-preserved body, but rather to skid in sideways, totally worn out, shouting "...holy sh.t...what a ride!" >> There might be some, somewhere. But everything I've seen so far is >> 120 volt, just lots of it. The difference is, when we're on 30 amp, [quoted text clipped - 10 lines] > > Hunter The low amp load Coleman Mach's were designed for that. In addition Winnebago has the Power Line Energy Management System that monitors and controls power usage. With both, 13,500 btu units running, both desktop computers, TV, Tivo, electric WH, and fridge, my total amp usage is 22 amps. If the usage gets to high, the Power Line will first turn off the compressor to the rear AC, then the fan to the rear AC, then the refrigerator. The coach was *designed* to use both roof AC's on 30 amp. Signature"Everyday I beat my own previous record for number of consecutive days I have stayed alive." http://www.bobhatch.com http://www.tdsrvresort.com >The low amp load Coleman Mach's were designed for that. In addition >Winnebago has the Power Line Energy Management System that monitors and >controls power usage. With both, 13,500 btu units running, both desktop >computers, TV, Tivo, electric WH, and fridge, my total amp usage is 22 amps. >If the usage gets to high, the Power Line will first turn off the compressor >to the rear AC, then the fan to the rear AC, then the refrigerator. Cool, okay..... Hunter -- http://members.aol.com/hhamp5246/roadtrip2005.htm Life's journey is not to arrive at the grave safely in a well-preserved body, but rather to skid in sideways, totally worn out, shouting "...holy sh.t...what a ride!" > The low amp load Coleman Mach's were designed for that. In addition > Winnebago has the Power Line Energy Management System that monitors and [quoted text clipped - 5 lines] > > The coach was *designed* to use both roof AC's on 30 amp. You know- I see these reports from many people using this setup, but I just have a hard time adding up the numbers. The lowest Coleman I have seen (rated at 13,500 btu/hr) is right around 10 amps- this at 95° outside, 75° inside. Add to this 3 amps for the refrigerator, 5-7 amps for the converter and any other 120 volt draws, and you come out above 30 amps. One thing to note is that A/C makers basically put small compressors mated to big coils to get the high efficiency units- DuoTherm doesn't come right out and say 13,500 btu/hr for their High Efficiency units- they say "equivalent to.." I have no reason to doubt- just that the numbers simply don't add up. SignatureChris Bryant http://bryantrv.com > You know- I see these reports from many people using this setup, but I > just have a hard time adding up the numbers. The lowest [quoted text clipped - 9 lines] > > I have no reason to doubt- just that the numbers simply don't add up. When I see you later this year we I will plug the rig into 30 amp and you can watch the Powerline. When I reported the 22 amps, it was with all those things running. We'll start with as much off as possible, and add one thing at a time. Now, keep in mind that my electric WH is a HotRod (sp), so the watt usage is pretty low. I do know that it is *rare* for us to pop a breaker on 30 amp. It will happen if Mary hits the microwave with too many other things on. Has never happened with 50 amp. Signature"Everyday I beat my own previous record for number of consecutive days I have stayed alive." http://www.bobhatch.com http://www.tdsrvresort.com >Chris Bryant <bounces@bryantrv.com> wrote: >> The low amp load Coleman Mach's were designed for that. In addition >> Winnebago has the Power Line Energy Management System that monitors and [quoted text clipped - 19 lines] > >I have no reason to doubt- just that the numbers simply don't add up. Yesterday we were in a state park with very good 30 amp service. With both 13,500 BTU A/C units running and the fridge turned to propane, we were drawing 29.5-31.5 amps, with the voltage holding at 118-120. The inverter was running the sat receiver, TV, etc. We ran all that stuff for about three hours. The park circuit breaker never tripped. That is the first time we have been at a 30 amp site that kept such good voltage at that level of draw. Other times we have tried to run both A/Cs, the voltage dropped to the point that the current draws became too high. SignatureDD >Hunter <HHamp5246@aol.com> wrote: >>There might be some, somewhere. But everything I've seen so far is 120 volt, >>just lots of it. The difference is, when we're on 30 amp, we can run 2 AC's, [quoted text clipped - 10 lines] > >Hunter As long as the high current draw does not cause the park voltage to drop, the A/C doesn't know the difference. SignatureDD >>> So after your change you can ONLY run on full 50amp 2-leg service >>> even though you're not using but 120vt? [quoted text clipped - 5 lines] > Even if I don't "understand" that's no reason for you to reply like > that to a valid question (this isn't RORT). Sorry, I didn't see it as a question, but a statement of fact, that was not factual. > Actually I "do" understand how the "systems" work but perhaps I don't > understand how the 30amp to 50amp adapter works. I assumed it [quoted text clipped - 5 lines] > and I withdraw my objections (and only hope that the few RV's with > real 240vt equipment never tries to use one of those!!). Read Rams reply. There are a very few, if any, RV's that have 240 volt equipment. You can even get an electric cooktop that is 120 volt and will run on 30 amp, you just need to watch usage when on 30 amp. I know this because we were looking for one to put in the MH. Maybe you know of a rig that uses a 240 volt "something", but I've never seen one. It doesn't mean they don't exist, it just means I've not seen one. Like you say, it combines, or jumpers the 2 hot legs in the 50 amp cable to the one 30 amp hot. It feeds both buses of the main with the same 120 volt leg. I was parked next door to a guy in Bangor with a big, all electric rig. Prevost. None of the equipment was 240 volt. He did have a 10.5 kw generator though. Signature"Everyday I beat my own previous record for number of consecutive days I have stayed alive." http://www.bobhatch.com http://www.tdsrvresort.com
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