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100 amp (not 50) vs 30 amp service

Yahoo Message Number: 4796
Hi Folks,

Technically, on shore power, the dual 120 vac 50 amp breakers provide 100 amp capability while the single 30 amp breaker is 30 amps. An 8000 watt generator with dual 35 amp breakers provide almost 70 amps (4000/120 = 33.3 amps or 66.7 amps total).
Also note that the engine alternator is a cream puff when it comes to recharging the batteries normally recharging in the 40 amp range while the inverter is aggressive with reaching 150 amp charge rates even with a small discharged condition.
Fred Kovol

Re: 100 amp (not 50) vs 30 amp service

Reply #1 –
Yahoo Message Number: 4801
Thanks, Fred

After posting the original question, additional surfing turned up the following link:

http://users3.ev1.net/~crossstitch/RVWiring/wiring.html I got it from the Escapees discussion group.
It shows that what is refered to as 50 amp plugins provide nearly 3 times the capacity that 30 amp plugins provide.
Bill Harris
03 Allure 30912

Quote from: fredkovol

Hi Folks,

Technically, on shore power, the dual 120 vac 50 amp breakers

provide

Quote
100 amp capability while the single 30 amp breaker is 30 amps. An

8000

Quote
watt generator with dual 35 amp breakers provide almost 70 amps > (4000/120 = 33.3 amps or 66.7 amps total).
Also note that the engine alternator is a cream puff when it comes

to

Quote
recharging the batteries normally recharging in the 40 amp range

while

Re: 100 amp (not 50) vs 30 amp service

Reply #2 –
Yahoo Message Number: 4802
Fred, how about enlightening me and others as to why the Onan Quiet Diesel
8.0

KW generator has just one breaker as compared to the PT 7.5 with two? On my previous coach with the 2 breakers, I didn't lose everything when one circuit was over-loaded.

Walt Rothermel
03Allure30811

Re: 100 amp (not 50) vs 30 amp service

Reply #3 –
Yahoo Message Number: 4807
Hi Folks,

Our 2000 Allure has a 8 KW powertech diesel generator which has two 35 amp breakers which are not mechanically connected. This could mean that if one 120vac leg is overloaded and the breaker trips, the other breaker may not trip and the loads on that circuit continue to operate. As to why the onan has one breaker, perhaps it's really two breakers with only one trip lever showing; this is a safer mechanization as it better protects the generator from overloads if one 120 vac leg is overloaded. I remember some house breakers built that way. My opinion is the powertech is a lesser expensive unit with less engineering implimented.
Fred Kovol

- In Country-Coach-Owners@yahoogroups.com, Spiker1029@a... wrote:
Quote
Fred, how about enlightening me and others as to why the Onan Quiet

Diesel

Quote
8.0

KW generator has just one breaker as compared to the PT 7.5 with

two? On my

Quote
previous coach with the 2 breakers, I didn't lose everything when

one circuit

Re: 100 amp (not 50) vs 30 amp service

Reply #4 –
Yahoo Message Number: 4811
Quote from: Spiker1029@a\.\.\.
Fred, how about enlightening me and others as to why the Onan Quiet

Diesel

Quote
8.0

KW generator has just one breaker as compared to the PT 7.5 with

two? On my

Quote
previous coach with the 2 breakers, I didn't lose everything when

one circuit

Quote
was over-loaded.

Walt Rothermel
03Allure30811
Walt, I'm nor Fred but this difference between PT and Onan was confusing to me. On my '97 Intrigue I had a 8KW PT and I ran everything. WE traded for a new 2001 Intrigue that came with a 8KW Onan Quiet Gen. For the first time, we started tripping the Gen breaker. My brother-in-law offered the following explaination.
The PT gen is a relay logic, constant speed gen set. You set the cycle rate (60) by adjusting the engine RPM. As the electrical load increases, the fuel supply (Injectors, etc)increases so as to maintain a constant speed so that the frequency remains constant at 60 cycles.

For the Onan, the RPM varies with the load. Since every Onan gen I have ever owned (on other motor homes and boats) ran at a constant speed and you set the cycles by adjusting the speed, something was up. According to Glenn (my brother-in-law) the Onan actually supplies a inverter (inside the gen housing)that then supplies the current at 60 cycles. Depending on which Onan manual you have, the electrical schematics show the inverter.

Now, what difference does all of this make? The 8 KW Onan does not provide a full 8000 watts to the coach. The difference is the inverter loss. We get a quieter, varible speed generator but we do not get the full 8000 watts.

I hope this answer gets posted correctly. I do pretty good with Email but this group thing still confuses me.

As an aside, Winnebago and other coach builders are using a device that monitors the total load. It prevents both A/C units from starting at the same time. I've seen it in their coaches at Lazy Days and have tried several web sites but I haven't been able to run it down.

Hope some of this helps.
Dr. Bob

2001 Intrigue
 

Re: 100 amp (not 50) vs 30 amp service

Reply #5 –
Yahoo Message Number: 4814
Thanks to Fred and DR. Bob for the quick responses re two breakers vs. one.
I'm still confused, but my lack of electrical knowledge accounts for that.
It sounds like the "improvement" in gensets really isn't.

Walt Rothermel
03Allure30811