Upgrading to 50Amp service

[sibe]

Originally Posted by geordi

Split phase only matters if you are trying to combine them to reach 220vac. That isn't the goal here at all, and NOT how a 50 amp RV draws the power. There are going to be two hot legs from the generator to run two AC units. If they are on the same phase, that is annoying (if you wanted to upgrade to a basement AC or something that needs 220) but not an issue in this case b/c the two hot legs are utilized separately as 120 each.

I do not know of a single generator that only provides a single hot leg, yet is capable of 50 amp delivery. The number of breakers on the generator itself does not count.

I have seen them wired funny in older RV but newer a typical 5500 or 7k will do as you say before any trasnfer switch , and nuetrals tied , landed together at genny.. I just pulled down the onan \service install pdfs

[geordi]

Originally Posted by sibe

I have seen them wired funny in older RV but newer a typical 5500 or 7k will do as you say before any trasnfer switch , and nuetrals tied , landed together at genny.. I just pulled down the onan \service install pdfs

I have an Onan gas 5500 in my older coach, originally had a Kohler 5k gas in that coach, and briefly had a Generac (I think it was 6k) in the same unit. ALL of those have been (or are) split phase so you could get 220VAC if you wanted it for some reason - although the coach doesn't need that for anything as it is a 30 amp. It does have 2 AC units and the second hot leg is only for that second AC unit.

My QD7500 diesel seems to be a non-split-phase as the connections at the transfer switch that I tapped to add my 50 amp socket, provide me 2 hot legs with zero potential between them. That is unusual to me, but this is also a variable RPM diesel generator that (I believe) is an inverter to make the power. I again have the two separated hot legs for 120vac each, but no chance of powering a 220vac appliance.

All of them have a "bonded neutral" which is normal for a generator setup.

[twinboat]

Many of the 5500 to 6500 watt generators output 120 volts only. Both legs are in phase.

Lets use a 5500 watt generator as an example.
With both stators tied together, the 46 amp output can be shared between the 2 breakers. 30 amps to one and 15/20 amps to the other.

Wired for 240 volts, each stator will only output half the the total amps, or 23 amps in this example. They can't share that.
That leave 2 legs with less amps then needed to run 2 appliances.

If your running 2 ACs @15 amps, that leaves you 8 amps on each leg for water heater, microwave, coffee maker or fridge.

[geordi]

Unless there is something else happening (inverter genset pulling 3-phase variable frequency from multiple stator points and rectifying it internally) The gasser gensets should all have two stators at 180 degrees opposing positions.

That will result in the capacity for split phase operation and the proper frequency when the genset is spinning at 3600 RPM. 3600 RPM and a single contact point is 60 revolutions per second, correct power frequency for the USA.

You are correct in that when the opposing stators are connected together (with a 220vac device) there is only the 23 amp total available... B/c that is at 220vac. HOWEVER the standard generator (again, NOT inverters or more exotic designs) still has the full 23-amps-per-leg available at 120. The generator is not running 30+20, it would be running 30+30 breakers b/c as a user / designer, you should be aiming to have the load balanced if you are going to come that close to the max capacity. An unbalanced genset will certainly still run, but it tends to be happier when the load is balanced across the magnets, there is less overall vibration and noise.

All of this is based on the standard design of powerhead though - it is entirely possible that many more current generators than I am thinking of, are available as variable-RPM inverter designs. An easy way to tell is if the RPM of the generator is generally constant under all loads, or if there is considerable speed changes. If it is changing speeds, then it CANNOT be the older style with 180 degree opposing stators - as the output frequency would vary and drive electronics and motors nuts, likely causing damage.


All of this is academic however. From the standpoint of the USER / load center... There are two incoming 120VAC hot legs. NOTHING in the 30 amp coach would be designed or desiring 220VAC, so the question of phase doesn't matter. The generator produces 2 hot legs somehow. Outside of the generator casing, they remain separated all the way through to the devices. So it doesn't matter: they could be precisely the same frequency, or the waveform could be 120 degrees apart (2 legs of 3 phase supply)... or they could be 180 degrees apart. A meter would tell the tale instantly.

But from the perspective of making the connections outside of the generator: Connect a meter to one hot leg and to the neutral, and you should see 120vac. Do the other hot, and also 120vac. That's what you want for happy devices. All you are doing is making a plug-and-socket adapter for your specific situation.

[sibe]

Not to toss this all over,, OP needs to let us know or a pic of wiring as is, is there a transfer switch. or power manager..

Adding a 50A for pediestal is possible, simple maybe. or with a proper transfer switch since pedestils have 2 50amp hotlegs with a 100 amp potential..
the 5500 genny has a 46 amp or 23 watt per leg potential.. splitting the rv circuits on the panel with make OP happy if done right when running the genny .. but feed ing a 2 pole 50Amp panle from that 5500 genny can be an issue as potentials are conserned amd use..

[yeloduster]

Originally Posted by Maj734

we have a 99 dolphin 5360 with 30 amp service. Surprisingly this rv has 2 AC units.. during the day we can not run both without tripping breakers. Has anyone upgraded to 50amp service? Is this even possible? TIA ��

I solved this problem on my motorhome. Works great!

It would be fairly easy to build an adapter so that the 2 shore power cords could be plugged into a 50 A socket.

See this Thread for details of the wiring and discussion about it.

This works perfectly for me. I can run both airs when on shore power by plugging in both the old 30A shore power cord and the new 20A power cord that I added.

[sibe]

Originally Posted by yeloduster

I solved this problem on my motorhome. Works great!

It would be fairly easy to build an adapter so that the 2 shore power cords could be plugged into a 50 A socket.

See this Thread for details of the wiring and discussion about it.

This works perfectly for me. I can run both airs when on shore power by plugging in both the old 30A shore power cord and the new 20A power cord that I added.

yep if they are split inside and you want a cord and 2 plugs or so,,, the 2 ac can be happy ,, LOL

alot of info from others and by me... all dependent of what your needs may be..
I had one RV that had a recpt for genny, shore power would plug into recpt wheruning gnny or inverter i put in..., no fancy shedding or power system. plug and play..choice the power.. LOL

[geordi]

Originally Posted by sibe

yep if they are split inside and you want a cord and 2 plugs or so,,, the 2 ac can be happy ,, LOL

alot of info from others and by me... all dependent of what your needs may be..
I had one RV that had a recpt for genny, shore power would plug into recpt wheruning gnny or inverter i put in..., no fancy shedding or power system. plug and play..choice the power.. LOL

That's probably the easiest way to do it, a "manual" transfer switch and no way to screw it up and create a loop or backfeed the power. The only downside is that the microwave will have to have the clock reset every time you change power sources.

[yeloduster]

Originally Posted by geordi

That's probably the easiest way to do it, a "manual" transfer switch and no way to screw it up and create a loop or backfeed the power. The only downside is that the microwave will have to have the clock reset every time you change power sources.

Nope...microwave is operated from the 30 amp circuit. Provided you don't unhook the 30 Amp shore power, switch from shore power to generator or otherwise interrupt the 30 Amp service switching the 20 Amp service from shore to generator or back affects nothing but the one A/C. In my case the front A/C.