BAC Forum
General Boards => Technical Support => Topic started by: Jason Worman on January 25, 2020, 05:50:33 PM
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Hi All,
I have a quick questions. Should the inverter breaker trip when I run more than two items? Have found we can run two space heaters, or dehumidifier or heater or heater and microwave just fine, but if we try to run let's say 2 space heaters and dehumidifier the inverter breaker trips. Have tried moving the items to different outlets but always the same results. We have the 2000 watt Xantrex Freedom 458 inverter.
Thanks
Jason Worman
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Yes! The breaker should trip. You are dramatically overloading that circuit. One space heater is all you should run on that circuit. The pass-through circuit in the inverter is not designed for heavy use items. Resistance heaters draw a significant amount of amperage. Many Motorhome owners have made minor modifications to allow the use of a second space heater. Some use the circuit for the engine block heater for a space heater while on shore power. I use the circuit from the original absorption refrigerator since I have installed a residential fridge in my coach. Constantly tripping that circuit breaker will cause the breaker to fail early as well as creating a fire hazard on the overloaded circuit.
Richard
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Richard,
If you have a minute, I have a few more questions if you would like to give me a call. 541-707-7415. How can the coach run two rooftop AC's without tripping a break?
Jaso
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Hi all,
One more question. Is there a way to figure out which outlets go on the two legs? And if so, could I place each separate heater or the dehumidifier on separate legs? We are camp hosts here on Oregon coast and I could run a heavy duty extension cord out to pedestal for dehumidifier.
Thanks
Jason
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Jason
I do not do well on phone calls (hearing loss), so I will try to give you a quick synopsis of motorhome electric panel wiring. A 50 amp service to an RV is actually two 50 amp circuits wired into a breaker box (100 amps usable power). I will use my 2006 Monterey as a classic example. My front and rear AC units are wired off of 20 amp circuit breakers one on each of the 50 amp circuits in the main breaker box. My inverter/charger is wired off of a 30 amp breaker on one of those 50 amp circuits. Other heavy draw items also have their own breakers in that main box (washer/dryer, hot water heater, refrigerator, engine block heater, etc...). So, the inverter/charger only has 30 amps to work with. That 30 amps is additionally broken down in a sub panel with multiple 15 and 20 amp circuit breakers. My microwave is on a 20 amp circuit by itself. The entertainment stuff (TV etc.) is all on a 15 amp circuit breaker. The remaining electric plugins in the living area are wired into a 20 amp circuit breaker. If I plug in a space heater into one of those plugins, it will consume up to 15 amps of the available 20 amps of power. If I plug in a second space heater into a plug that is on the same breaker, I am trying to draw 30 amps from a breaker rated at 20 amps. Even if I plug the space heater into a plug that is on a different circuit breaker in the sub panel, I am now drawing the maximum rated 30 amps from that breaker. If I turn on anything else (microwave, TV, whatever), I have dramatically overloaded that circuit. The sub panel has multiple circuit breakers of 15 or 20 amps each, BUT, the accumulated power draw from all circuits in the sub panel cannot exceed 30 amps. In the same way, the accumulated power draw from all circuits wired off of each side of the main breaker box cannot exceed 50 amps. Since the engine block heater, refrigerator, washer/dryer, etc..., are wired directly from the main box, they provide potential power sources to use for aux. power draw to avoid the limitations of the 30 amp breaker attached to the inverter/charger. That is kind of an over simplified description of motorhome wiring, but I hope it makes sense and helps you understand what is happening.
Richard
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Jason
I use a small plug in outlet tester to test outlets (the kind with 3 lights that tell you if the outlet is wired correctly). (Or use a plug in lamp). Plug one of those into an outlet and then go to the sub panel (mine is in the bathroom). Turn off each circuit breaker one at a time. When the light goes out, you know which circuit breaker it is attached to. Repeat for all concerned outlets.
I commonly run a heavy duty extension cord (at least 12 gauge) from the pedestal. (Caution, 14 gauge is SMALLER than 12 gauge, 10 gauge is larger.) For me it is in the Summer when I need to run a second air conditioner and am limited to 30 amp service from the pedestal. So, Yes, you can run a heavy duty extension cord and take advantage of the 20 amp GFI circuit that is commonly available on the power pedestal.
Richard
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Richard,
That helps to explain alot. I guess being new I am still use to a traditional stick built house where you can run most everything at once. Part of the reason for wanting to run 2 heaters is it cuts down on propane use and we don't have to break down the rig to run and fill the tank. Thank you for your time.
Jason
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Richard,
If you have a minute, I have a few more questions if you would like to give me a call. 541-707-7415. How can the coach run two rooftop AC's without tripping a break?
Jaso
As Richard explained - the roof AC units do not feed from the Inverter.
Here's a simplified wiring diagram showing how the power flows. The Shore Power (or Generator) provides power to the 120VAC Main Circuit Breaker panel. That panel provides power for the roof AC units and also has a breaker/circuit that provides power to the Inverter. From the Inverter output, power goes to the inverter circuit breaker panel and onto the 120VAC outlets and such.
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Jason,
Another way to explain what Richard is saying is to convert all the things you are trying to operate into "watts" instead of "amps" The Inverter circuit is limited to the 30 amp circuit breaker that supplies power to it. Lets convert that from amps into watts. 30amps X 120 volts = 3600 watts. So with 3600 watts of available power from that circuit, lets start subtracting the "loads" you are trying to operate. Electric space heater = 1500 watts, tv's and audio video equiptment = 300 watts, dehumidafier = 800 watts, microwave = 1500 watts. Another space heater = 1500 watts. You can see it does not take too much to exceed the 3600 watts of available power. That is why we suggest to use another circuit that is not being used to power the 2nd electric space heater. Some use the engine block heater or the washer dryer circuit or the refrigerator circuit.
Hope this helps, Fred
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I cannot say that the Xantrex is the same as the Magnum 2k inverter but in researching mine on my 2005 Monterey, I discovered that the pass through on the inverter was wired with 10-2 to handle one leg and limited pass through for the interior outlets to 30a @110v. The inverter was designed to handle 2 legs at 30A each. All of the in house breakers were off this one leg, house breaker box tied both input legs together to power all the interior outlets. I thought it was kind of stupid to have 100A @110 available and only 30A @ 110 available for all interior outlets. I was able to rewire the coach with 10-3 and reconfigure the house breaker box so that we had 2ea. 30A circuits in the coach. This way we could split the high demand loads between the 2 circuits. I am not saying this can be done in your coach but if you need the power inside it might be worth looking into.
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Hi Jim, not really sure what Monaco had in mind back then but at todays standards, we live in an energy dependent society. If we go back to 2004 when your coach was built more than 50% of the RV parks only had 30 amp services. That may have been Monaco's consideration to limit the inverters output. It takes serious energy management trying to run a 100 amp coach on a 30 amp pedestal. That is why Intellitech came out with their EMS (energy management system) to automatically turn off "loads" that had an alternative energy source. Fred
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Fred,
Thank you helping to clarify the power usage in watts, makes sense. So when you say to use another circuit such as the engine block heater, do I need to install a new circuit breaker?
Jason
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Hi again,
I found my owners manual with all the wiring diagram schematics, and of course, the AC input and distribution schematic is missing. It is listed as E-0017. It is a stretch but would anyone happen to have a copy it? For a 1991 Contessa with the 3116 Cat engine.
Jason
Thanks
Jason
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Jason,
The wiring diagram you are looking for is in Coach Assist. Go down to Wiring Diagrams
Select in the following order;
-1974-1994 Beaver Wiring Diagrams
-Beaver Motorhome History
-Beaver Coaches 1968-1994
-Schematics 1984-1994
-Service Manual Schematics
Steve
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Jason, If you look at your circuit breaker box and the breakers are identified, 1 should say "block heater". The easiest way to utilize that resource is to find the duplex receptacle back in the engine compartment somewhere. It may have a hinged cover over the plug openings usually silver in color. If you can plug a 12 gauge extension cord into that recepticle and thread it into the bedroom area somehow and secure it along the way, you now have a 2400 watt dedicated circuit you can plug into. Your other choice is to add another receptacle and hard wire with romex and attach it to that same breaker and identify it on the lable. Fred
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Fred and Steve,
Thank you so much for the information. Again I find that being part of this forum is so helpful. Wish we could attend one of the rallies and meet everybody from this club.
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I used a lot of electric heat. To do that, I used heaters with a "low" setting that will then draw about 8 amps. Normal for us was a baseboard style, oil filled heater that fit behind the recliner location in out Monterey. It consistently sat there and radiated quietly.
There are also a variety of 2 amp (200 watt) heaters, sometimes called "personal heaters" that might used under a desk at work. (Apparently there is a segment of the population that doesn't wear warm pants to work in the winter!) Three of the 2 amp heaters spread around the rig isn't likely to overload the circuits and will provide a noticeable amount of heat.
The 2 amp heaters are also good for freeze protection in the bays if you need that. They are far more rugged than bulbs or lamps.
Lasco 200 watt "My Heat": https://smile.amazon.com/dp/B00538G5PI/ref=dp_cerb_1?th=1
As similar one at 500 watts: https://smile.amazon.com/AmazonBasics-500-Watt-Ceramic-Personal-Heater/dp/B074MX8VN5/ref=sr_1_4?keywords=AmazonBasics+500-Watt+Ceramic+Small+Space+Personal+Mini+Heater&qid=1580144247&s=home-garden&sr=1-4
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Bill,
Your comments always get a chuckle out of me, the part about wearing pants in the winter. That is a great idea to use 3 smaller heaters spread throughout the coach versus the two larger ones we now use, one is Dyson hot and cool unit the other is a Lasko model.
Jason