30 AMP breaker on a 8KW generator?

[AKBrick]

Hi Guys and Gals,
Obviously I didn't learn enough about electricity while operating a power plant for a job for 31 years.

While dry camping at the FMCA Rally in Albany, OR. a couple weeks ago, it was cold enough to have to run two heatpumps. While doing this we used our microwave and the TV. Welllll....we noticed that our electrical management panel was wacking out and was going up and down between 30amps down to 20amps and couldn't make up it's mind where to stay before the 30amp breaker on the generator tripped. This happened 3 times before I decided to not run both heatpumps. It turns out that the heatpumps pull a LOT more juice than the air conditioners. I didn't even think of that before. I just thought that since they were in the same unit that they would pull the same amount of electricity.

I guess I figured that an 8KW generator would be enough to power a 50 amp coach but it turns out that's not the case. I was bugged that there was only a 30 amp breaker on the generator than a 50 amp breaker. Well duh...I guess that's because a 8kw generator can't carry a 50 amp load. Is this the case or am I wrong?

I ran this buy the Gauranty service rep at the rally and he just smirked and told me about how much the heatpumps took to run them. It turns out that everything was working just fine thank-you.

Now I just need a 10KW generator. The problem with that is I have to get a higher end coach. Well maybe not, but I don't feel like forking out more bucks.

Ta ta for now,

AKBrick

[AKBrick]

Hi Guys and Gals,
Obviously I didn't learn enough about electricity while operating a power plant for a job for 31 years.

While dry camping at the FMCA Rally in Albany, OR. a couple weeks ago, it was cold enough to have to run two heatpumps. While doing this we used our microwave and the TV. Welllll....we noticed that our electrical management panel was wacking out and was going up and down between 30amps down to 20amps and couldn't make up it's mind where to stay before the 30amp breaker on the generator tripped. This happened 3 times before I decided to not run both heatpumps. It turns out that the heatpumps pull a LOT more juice than the air conditioners. I didn't even think of that before. I just thought that since they were in the same unit that they would pull the same amount of electricity.

I guess I figured that an 8KW generator would be enough to power a 50 amp coach but it turns out that's not the case. I was bugged that there was only a 30 amp breaker on the generator than a 50 amp breaker. Well duh...I guess that's because a 8kw generator can't carry a 50 amp load. Is this the case or am I wrong?

I ran this buy the Gauranty service rep at the rally and he just smirked and told me about how much the heatpumps took to run them. It turns out that everything was working just fine thank-you.

Now I just need a 10KW generator. The problem with that is I have to get a higher end coach. Well maybe not, but I don't feel like forking out more bucks.

Ta ta for now,

AKBrick

[BigSkyBob]

My Onan 8KW QD generator has a 35 amp breaker. I was exercising the generator today running both A/C's, the fridge and one TV and the EM panel indicated 39 amps. It ran for 1.5 hours with this load without tripping the generator breaker. Go figure.

[Route 66]

You don't need a 10KW generator.

The 30 amp breaker is a ganged breaker with a 30 amp breaker on each leg.

I frequently run both AC/heatpumps on my 7.5KW Onan.

There should be one AC/heatpump on each leg.

It sounds like something is not wired correctly.

[speed racer]

These generators are not designed to run everything in the MH at the same time. That's why they call it an RV not a HOUSE!

[Route 66]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">These generators are not designed to run everything in the MH at the same time. </div></BLOCKQUOTE>

That is correct.

I cannot run everything at the same time, but I can run 2, 3 or 4 things at once depending on their amperage requirements.

[Don (W5IT)]

Something to check would be how the loads are distributed on each buss.

The loads were not distributed properly on the two busses in my fiver from the factory. It would actually trip the shore power breaker at some campgrounds.

Well after a check of the loads on each buss I found out why. After re-distributing the loads on the two busses I have had no further problems.

Of course I should have checked this from the start as I have seen this situation before. Even in high end coaches by well respected manufacturers. So I should have checked this before I even made the first trip.......

But like most, I did not until the problem showed up.....

[MO _ Jack]

If I am doing this right:

WATTS = AMPS * VOLTS

AMPS = WATTS / VOLTS

8000 WATTS = 66 AMPS TOTAL
(8000/120 =66.66)
33 AMPS PER LEG
THUS THE 30 AMP BREAKER(S)

Jack

[Route 66]

You got it right.

[AKBrick]

Thanks guys,
I woke up this morning trying to remember OHM's Law and then I couldn't go back to sleep. You've solved it for me.

I'll also have to check what's on each leg for general knowledge of my coach.

Thanks again all,

AKBrick

[Hillbilly2]

Are you sure it's a heat pump? Heat pumps generally draw the same whether heating or cooling, It may be electric strip heat, or the emergency heat may have kicked in, which is electric strips, which draw considerably more power. Could be the antishort cycle timer not working though, judging from the amp surge, this could be it. If power is interupted to the compressor, it locks the compressor out for a predetermined time, allowing gas pressures to drop, allowing the compressor to restart normally. Just a few things to ponder.

[Hillbilly2]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by MO _ Jack:
If I am doing this right:

WATTS = AMPS * VOLTS

AMPS = WATTS / VOLTS

8000 WATTS = 66 AMPS TOTAL
(8000/120 =66.66)
33 AMPS PER LEG
THUS THE 30 AMP BREAKER(S)

Jack </div></BLOCKQUOTE>

You are correct sir!

[sparetire]

If it is a true heat pump, the system just reverses and extracts heat from the outside air. They don't work very well below 35 degrees as a rule, and then some other type of heat must be used. In RV's it is a heatstrip (resistance coil) mounted in the A/C unit. There are regular RV A/C's that are not heat pumps, but they have a heat strip installed.

On either system the compressor is not supposed to run when the heat strip is energized because the amount of wattage drawn would be prohibitive. You may have a unit that is mis-wired internally or has a relay or electronic control stuck allowing both compressor and heat strip to be energized at the same time in one of your 2 units. Check the actual amperage draw of each unit, separately. You may find one that pulls a bit more load than it should.

Happy travels,
Sparetire

[AKBrick]

Thanks for the info guys. Some of it may be a little over my head but not too bad. I think I'll let Gauranty RV Service look into it in August. I never checked the amperage of each heatpump. I should, but with the 100 degree outside temps here in Deer Park, WA. I think I'll pass on running the heatpumps for awhile.

AKBrick