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 > AC voltage and line loss

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cm2785

So Cal

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Posted: 07/07/18 12:15pm Link  |  Quote  |  Print  |  Notify Moderator

MrWizard wrote:

I bought this Bounder 36S, last Sept, moved from the DP to the Bounder in Dec
I have not yet plugged in anywhere
Strickly on generator and Add on inverter
This RV has 30 amp shore cord
I have the intellitec load control also
The rear A/C is on a breaker in the panel
It appears the front A/C is on the 20 amp circuit breaker of the Onan 5000 and goes thru the inteltec but not thru the breaker panel
No breaker in the panel turns the front A/C off

Because it was 116F yesterday, and 95F at 2am this morning
The generator has been on for 26 hours, since Friday morning 7am
Today the prediction is 111F


Are you in SoCal too by chance?

Is the Onan only putting 20 amps into the RV when running? I thought the Onan put out 41 amps or something so I was under the impression the power was better on the Generator than shore power. Am I wrong?

cm2785

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Posted: 07/07/18 12:21pm Link  |  Quote  |  Print  |  Notify Moderator

time2roll wrote:

(copied from link below): Section 210.20(A) of the code basically says that a circuit breaker for a branch circuit must be rated such that it can handle the noncontinuous load plus 125% of the continuous load. (A continous load is one where the maximum current is expected to continue for 3 hours or more.) In other words, the breaker needs an extra 25% capacity of the continuous load for headroom. That, of course, means you need a larger, more expensive breaker.

https://blog.schneider-electric.com/data........fusion-80-vs-100-rated-circuit-breakers/

No one actually applies this rule as it is not required for an RV because all items are short term or thermostatically controlled so by definition an RV is not a continuous load. However as you have experienced it is easy to have the air conditioners run continuous for 10+ hours and the EMS will hold the RV very close to 30 amps for well over the 3 hour requirement. Then you have the booster that will draw more amps to get the voltage corrected.

IMO this can put you in the continuous service definition. Ever wonder why so many 30 amp connectors and adapters are burn, worn, and heat damaged? OK not just this but I believe it contributes significantly.

This is part of the reason I suggested all breakers off if running 2x A/Cs. Yes you will be running on battery power for the 12 volt systems while the 120 volt system is under stress. That last 4 amps can make a difference. Turn the rest back on an hour or so after sunset when the system is less stressed. Otherwise make do with one A/C or find 50 amp power.

JMHO


Thanks for the info, are you saying I can put a better breaker on the main that can handle the continuous load? I have 50 amp power available and the dogbone to use it, but obviously I’m not a 50 amp rig... I would gladly pay an electrician to make me 50amp but I can’t get a clear answer on whether my Intellitec will still function. Believe it or not i like the stupid thing (I would ditch it faster than I could click check out if there was a newer digital replacement!)

MrWizard

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Posted: 07/07/18 12:37pm Link  |  Quote  |  Print  |  Notify Moderator

yes i'm in SoCal
i'm sure the generator is running near max
but at these temps the A/Cs are hot and pulling full power
the Onan gets hot and gets to point where it is difficult for it to do compressor restarts
put the A/C's on auto, select a low enough temp on the stat, that the A/C comes on and stays on, does not cycle the compressors
makes it a bit cool in the morning, but that helps combat the heat penetration
did 20hrs on batteries for the 12v systems (led lights, water pump, fridge and thermostat controls) aka parasitic loads
did battery charging this morning 3hrs this morning before turning off converter circuit breaker
ran the generator and one A/C all night last night, right now 105 here


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cm2785

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Posted: 07/07/18 12:43pm Link  |  Quote  |  Print  |  Notify Moderator

MrWizard wrote:

yes i'm in SoCal
i'm sure the generator is running near max
but at these temps the A/Cs are hot and pulling full power
the Onan gets hot and gets to point where it is difficult for it to do compressor restarts
put the A/C's on auto, select a low enough temp on the stat, that the A/C comes on and stays on, does not cycle the compressors
makes it a bit cool in the morning, but that helps combat the heat penetration
ran the generator and one A/C all night last night, right now 105 here


I’m in Burbank and it’s 105 here too.. my AC’s are brand new 13.5k units so the one in the bedroom will freeze me out at night, even last night. My sensors on the Inteli seem to be **** so I run on low AC always. Is the Onan really only putting 20 amps into the RV? That doesn’t seem right.

MrWizard

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Posted: 07/07/18 12:50pm Link  |  Quote  |  Print  |  Notify Moderator

no you cannot just replace the main breaker with a 50amp breaker

yes you could be rewired to 50 amp service

put that means a new breaker panel and new transfer switch and new wire from TS to breaker panel, plus the new shore cord (which would be the least costly part)

would cost you quite bit to do it

yes the intellitec climate control would still work
but would not be needed when on 50amp shore power

rgatijnet1

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Posted: 07/07/18 01:03pm Link  |  Quote  |  Print  |  Notify Moderator

When/IF you switched from a 30 amp to a 50 amp service there is a lot of things to be changed. To put it in basic terms, you are going from a 120 volt 30 amp input to a 240 volt 50 amp input. As mentioned, this means changing your complete input main breaker panel as well as all wiring leading up to it, including the transfer switch, etc.
It would be much easier to put the second AC on it's own circuit with it's own extension cord that could be plugged in to a separate 120 volt/20 amp outlet on the pedestal. Most RV park pedestals have two outlets and some have three. They are 50 amp, 30 amp, and 20 amp(which looks like a standard wall outlet.
This would mean that your 30 amp main breaker panel is only dealing with one AC unit and a completely separate circuit is taking care of AC number 2.

pianotuna

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Posted: 07/07/18 01:13pm Link  |  Quote  |  Print  |  Notify Moderator

Hi Time2roll,

Actually a few of us do apply the rule. I do use deoxit on connections before I plug in (for the first time in a particular location).

You are correct that the rule is not a requirement for plug in devices, which means RV's can legally ignore it.

time2roll wrote:


No one actually applies this rule as it is not required for an RV because all items are short term or thermostatically controlled so by definition an RV is not a continuous load. However as you have experienced it is easy to have the air conditioners run continuous for 10+ hours and the EMS will hold the RV very close to 30 amps for well over the 3 hour requirement. Then you have the booster that will draw more amps to get the voltage corrected.

IMO this can put you in the continuous service definition. Ever wonder why so many 30 amp connectors and adapters are burn, worn, and heat damaged? OK not just this but I believe it contributes significantly.



Regards, Don
Full Time in a 28 foot Class C, 256 watts solar, 556 amp hours of AGM in two battery banks 12 volt batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

time2roll

Southern California

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Posted: 07/07/18 01:16pm Link  |  Quote  |  Print  |  Notify Moderator

cm2785 wrote:

Thanks for the info, are you saying I can put a better breaker on the main that can handle the continuous load? I have 50 amp power available and the dogbone to use it, but obviously I’m not a 50 amp rig... I would gladly pay an electrician to make me 50amp but I can’t get a clear answer on whether my Intellitec will still function. Believe it or not i like the stupid thing (I would ditch it faster than I could click check out if there was a newer digital replacement!)
I guess that was not obvious [emoticon] Two A/Cs in a Class A (or any RV) is usually 50 amp service.

No you cannot just pop in a 50 amp breaker. And as long as the breaker holds you are fine.

If you are plugged into 30 amp connector.... yes I would use your adapter to use 50 amp service if you have a connector right there. Often you will get better voltage on the 50 amp. All you can do is try. Give the air conditioners 3 to 5 minutes before you restart them.

If this is more than a one time event I would be looking at upgrading to 50 amp service and even give up the energy management to do it. You would have to manually limit power if you only had 30 amp service available.


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cm2785

So Cal

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Posted: 07/07/18 01:30pm Link  |  Quote  |  Print  |  Notify Moderator

Thanks guys, I know I can’t just add a 50 amp breaker. I was referring to the post about all breakers on a branched circuit have to handle 125% load.. yet they didn’t follow that in RV’s

MrWizard

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Posted: 07/07/18 01:35pm Link  |  Quote  |  Print  |  Notify Moderator

who said anything about the genny only doing 20amps
i think you got confused someplace

i did say the rear a/c is on a 20amp breaker in the the panel with the rest of the 30amp house
and the front a/c is on the 20amp breaker of the onan
the onan 5000 has (2) breakers a 30 for the house and (1)a/c
and a 20 for the second a/c
this is common in almost all 30amp rvs with a generator

i also think it should be done differently
the onan is rated for 41.7 amps, but it is not (1) 40 amp breaker into the RV
which is the way i think they should be wired
generators are not built with mis-matched stator output windings
but they ship RV gensets with centered tapped wiring and expect to split an imbalanced load, at approx 27/14
when the windings are built do 20 on each winding separated or 40 when wired combined

so you get an RV with 50amps of combined CBs on a 41amp generator
and the load is NOT balanced across the generator output windings
unless you turn off everything except the (2) A/C units

lets say each A/C is drawing 13amps, everything else is off
theoretically you have 7amps extra on each circuit breaker 14amps total
put you can't pull that 14 amps thru only one side, say the house side to power the MW, that one winding won't do it you get a voltage drop

* This post was edited 07/07/18 03:47pm by MrWizard *

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