[Larry & Diane]

A 50 amp service is 50 amps per leg. However, it is recommended that you not exceed 80% of the rated capacity (40 amps) while in use.

[Archived]

Greg… it is 50 amps per leg… I keep my incoming shore power amps set at 47 amps… that leaves a 3 amp margin to keep you from throwing the breaker on the outside pole… The Vantare is set up to draw from the batteries if you reach 47 amps without tripping the pole breaker.

I set both inverters to 47amps incoming.

Hope this helps.

Diane

[Archived]

My former company manufactures electric power outlets. We buy circuit breakers by the tens of thousands and according to the manufacturers (Siemens, Square D, etc) the circuit breakers will carry 80% of their rating as Paul stated continuously. Beyond that there is no assurance they will not trip.

As a result I try to limit my max amperage per leg at 40 amps on 50 amp service, 24 total both legs on 30 amp service and I don’t even bother using a 20 amp circuit except for storage.

[Larry & Diane]

Jon made a very critical point in his post. When using a 30 amp source, you must limit both legs of current to less than 30 amps total. On a 50 amp service, the limit is per leg.

You will also likely have to modify your house battery charging set points while on 30 amp power. Power management will be important.

[Archived]

Greg there now you have it from Jon… 40 amps not 47 amps like I said.

Unfortunately… I can’t run leg 2 on 40 amps I don’t think….as the way things are on my bus I draw a constant 45 amps with both airs running on leg 2… it seems all my heaviest loads are on leg 2…. leg 1 pulls around 35 amps loaded with both A/Cs.

I do have to turn my chargers down from 15 amps sometimes to steal a few amps.

Never have a tripping the pole problem however… guess we have just been lucky.

Jon knows his stuff…

Diane

[Archived]

Just to clarify……..A 50 amp breaker MAY handle loads in excess of 40 amps continuous.

If a coach current draw is limited to 40 amps per leg and the shore power breaker trips or keeps tripping it is not a coach problem (as some campground owners will say). The probability is the breaker is failing or the breaker wires are loose inside the shore power box.

[Archived]

Jon,

I used to state the 80% rule like you do until someone called me on it. My basis for stating the 80% rule is that is what my power production team’s used as their criteria for circuit breaker replacement during our annual inspections. These were critical Air Force telecommunications facilities, so we would always err on the side of keeping the plant operational. After I was called on this I discovered I was more wrong than right.

Here’s what I discovered:

“To meet the requirements of Underwriters Laboratories Standard 489, molded case circuit breakers are designed, built, and calibrated for us on 60 Hz ac systems in 40°C (104°F) ambient temperature. When applied at ambient temperatures other than 40°C, the current-carrying capacity and/or trip charasteristics of the circuit breaker may vary.”

If you take for example Square D’s specification, http://ecatalog.squared.com/pubs/Circuit%20Protection/Miniature%20Circuit%20Breakers/QO-QOB%20Circuit%20Breakers/0730CT9801R108.pdf you can see that a breaker is not suppose to trip until it reaches it’s stated current rating as long as it’s temperature doesn’t rise above 104 degrees F. What you will also see is that our 80% rule roughly matches the top of the aceeptable temperature range of 140 degrees F.

In a CG environment we should never see temperatures at a braeker come anywhere near 140 degrees unless they have a loose connection. Loose connections are major contributors to fire so it’s comforting to know a breaker will trip prematurely when it gets hot. So, Diane and others should worry about running their loads closer to the stated breaker rating. Obviously, balancing power requirements between the two legs should looked at. Changes that occur after the coach is delivered or even sometimes options installed at the factory may result in an unecessary imbalance between the legs.

[Jerry]

The single most frequently reported complaint with power outlets is premature tripping and in almost every instance the CG failed to re-torque the breaker screws after receiving the new boxes and prior to their initial service.

When they are produced all connections are torqued using certified and calibrated tools, yet periodic re-torquing is required. I suspect while part of the problem might be vibrations during shipping it might also be the wire materials cold flow after the first tightening. As to temperatures we rarely see ambient temps of 140 degrees, but with the sun bearing down on a power outlet sitting beneath the noon time sun I would suspect the internal temps of the box are pretty hot. Add to that a slightly loose connection and a lower trip point seems almost a given.

[Archived]

Jon…

I talked to Ben Cummings today at length about the Vantare setup and he told me that I don’t really need to set the shore power below 50amps or mess with the charging amps like I do… he says Vantare set it all up automatically to manage that part… The inverters will turn the chargers down when more amps are needed… I was not aware of that. I wish I could remember everything he said.

He did say that he thought he and Rick May will be coming to the Branson Rally in October which will be great.. I hope all the PC Vantare owners will be there… these guys know their stuff.

Thanks for your time today Ben if you read this.

Diane

[Archived]

the other day I had the gen running and it tripped the inverter breaker in the bay ( 24v 250a breaker),I was not paying super close attention, but I think is 35-40 amps, but it still kick the breaker out. Any suggestions to why?

[Archived]

Greg,

I can’t answer the question, but a breaker of that size is likely on the DC side of your electric system so keep the two circuits separate in your mind when seeking answers.

It could be as simple as a CB getting lazy and tripping, or it could signal a serious issue that cannot be ignored. If a breaker of that size trips again for your own safety do not reset it until you know the reason.

[Archived]

Greg,

Did you have the coach’s systems on and shore powered when you started the generator? Although inverters are designed to provide a full load switch from commercial power to inverter power, I don’t like doing it. If you did switch from commercial to generator power through the automatic transfer switch it’s possible the inverter kicked in for a brief moment. If there were significant AC loads on it could have caused the breaker to trip, even though it shouldn’t have.

See if it happens again,

[Archived]

In the interior panel, I shut down all the heavy amp loaded items when ever I switch from gen, invert or shore to make sure that heavy draw is not present at the time the load switches from one source to the other.

Again, this may have been an isolated issue, I have not had it again, but I have not been running the gen, since I am connected to shore power…

[Archived]

On your Vantare, there is no “automatic unloading” of 120volt loads, and the inverters actually invert to phase shift and parallel with the generator, even if you are connected to shore power when you start the generator. The 120volt load on each leg should be less than 33 amps or you risk nuissance tripping of the DC breaker that feeds each inverter. Hope this helps.

Sincerely,

Ben Cummings

Parliament Motor Coach

[Davy]

I’ve had some success by placing a small fan outside, right under the breaker box, blowing up onto the breakers to keep them cool. I’ve done this on more than one occasion and it does work.