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plowjockey

electrical overload question

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I'm working on being able to run my house refrigerator of the inverter.   I discovered that my outlet that the refrigerator runs on is working on the same line as my coach outlets.  When shore power is on the refrigerator works just fine.  However, in inverter mode it doesn't and in fact if I try to use it, the GFI trips but not the panel breaker.  Two questions: 1) why does the GFI trip and not the panel breaker?  2)  if I want it to work with the inverter, should I run a dedicated line from the panel to the refrigerator outlet and make sure there is not a overload situation since I only have a 30 amp inverter?  If I bump the inverter up to 50 amp will it probably work just fine the way its currently wired?   

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plowjockey,

Welcome to the Forum.

Several questions, what refrigerator do you have and is your inverter Pure or Modified Sound Wave? Some makes of refrigerators will not work on a Modified Sound Wave Inverters. That being the case if you do change inverters be sure to get a Pure Sound Wave. 

Again Welcome,

Herman

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Is the outlet that the fridge is plugged into powered by the inverter automatically when shore power is off? Where is the GFCI which is tripping? Is it in the outlet the fridge is plugged into or is it in the inverter itself?

If the GFCI is tripping, you have an imbalance somewhere which the GFCI is seeing.

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GFCI are not circuit breakers and don't monitor the amount of electricity going through them.  They monitor the power going through the "hot" wire and make sure the power on the "neutral" wire matches it.  Any imbalance means there's a problem and it trips.  The leakage could be to the ground wire or to another source of ground.  It's there for your safety - not overloads. 

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Many residential fridges will trip a  gfci circuit, mainly because the compressor uses a start capacitor. The capacitor causes a brief imbalance between hot and neutral because of the discharge of the capacitor to aid in the starting of the compressor. A gfci breaker will  open with no more than 5 milliamps (that's 5/1000) of an amp, that is all that is allowed by law, many manufacturers set theirs to open a 4 mills to be less than the law requires. As mentioned above a gfci is not an overload protector, they are a shock protector, the human heart will quit working with 8 milliamps of electrical passing through it. The fridge should not be on a gfci, BUT BE SURE that it is on a grounded outlet.                                                             

 

Edited by kaypsmith

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I am assuming the refrigerator came in your MH connected to the outlets powered by a shore hookup. I would imagine the manufacturer did this due to the low inverter rating. I would leave things they way the MH came unless you want to change out inverters and possible a newer refrigerator.

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There is a lot of unanswered questions in your OP, is the house refrigerator inside the coach, or is it just on the same outlet that the rv is hooked up to. If inside the rv, did it come inside the rv, or is this a replacement fridge? What is the max amp draw of the fridge? How old is the coach, how old is the fridge?

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The first question I always asked when troubleshooting is "did it ever work?"  If it did work at one time, what has changed?

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12 hours ago, plowjockey said:

I'm working on being able to run my house refrigerator of the inverter.   I discovered that my outlet that the refrigerator runs on is working on the same line as my coach outlets.  When shore power is on the refrigerator works just fine.  However, in inverter mode it doesn't and in fact if I try to use it, the GFI trips but not the panel breaker.  Two questions: 1) why does the GFI trip and not the panel breaker?  2)  if I want it to work with the inverter, should I run a dedicated line from the panel to the refrigerator outlet and make sure there is not a overload situation since I only have a 30 amp inverter?  If I bump the inverter up to 50 amp will it probably work just fine the way its currently wired?   

Welcome to the forum. Help me get the terminology straitened out in my mind. Now are we talking about s standard RV absorption refrigerator that works on propane or 120 AC electric? Does it have an icemaker? When you talk about "in inverter mode" Is this an inverter you installed or a factory one? If it is one you installed did you run it direct to the refrigerator or just tie in into the circuit the refrigerator is on? What is the make model and year of your RV?

Bill

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Many (most) RVs come from the factory wired so the frig DOES NOT run when on inverter power.  

When I replaced the original absorption refer with a household unit I actually installed a second 2000 watt pure sine invertor dedicated to the refer.

Lenp

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If we're talking about an RV absorption refrigerator, the heating elements can develop an internal short to ground that trips the GFCI.  They're hard to test because after they cool, the short vanishes.  The heating elements aren't too expensive (if ordered online) or hard to change (YouTube).  Replacing it would be worth trying.  If it's a 1200 Norcold, it has two elements.

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Plowjockey , Could you post the Make, Model and year of your coach?

What refrigerator is install in the coach?

Is it OEM or a replacement?

Note, Many of the LP / electric refrigerator that are connected to the AC outlet behind the refrigerator is intended to power the Ice maker only and is not intended to supply power  from the inverters.

Rich.

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Want to thank everyone for their insight and willingness to help. I'll go from top to bottom on the responses and try to answer to the best of my ability.  General info:  2008 Safari Simba, bought with 23K and currently has 42K.  Refrigerator is a Norad model 1210im OEM, current under a/c 5.5 amp 660 w,  under d/c 2.7 amps 33w, 2400 BTUH.  Now this rest of info.

*the inverter does not start the refrigerator when shore power is off.  I initiate the start up

*the GFCI is located in the bathroom and supplies all the plugs forward in the coach.  Only the plugs in bedroom come from a different source.   

*thanks for the explanation of the GFCI function.  BTW,  the refrigerator never gets tripped when under shore/generator power.

*I also think its related to start up and causing me to think that I might need a bigger inverter 

*the motorhome came without an inverter.  The inverter was installed  20 months ago.

*the refrigerator is in the coach

*the refrigerator works on elec and propane, has an ice maker which is inactive.

*the refrigerator and all a/c plugs are in the secondary (inverter) panel and all coming off of one 20 amp breaker.  Also, the microwave is  supplied by this line.

*I'm not sure about the elements but would think that if that was the problem, it would also have the same issue under shore power?  

*I unplug that line going to the outlet and nothing happens to the fridge, so I think that's the only source.

I hope all the questions are answered, if not let me know and I'll fill in the blanks.

Thanks again for the help as the way it operates now really limits us.  I know you can't have everything when using an inverter (without spending a fortune) but I would just like lights, plugs, microwave & refrigerator.

 

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Plowjockey.

 Refrigerator is a Norad model 1210im, current draw when on ac is 3.6 amps.From the OEM spec sheet.

 Refrigerator is a Norad model 1210im OEM, current under a/c 5.5 amp 660 w, per  Plowjockey !

This refrigerator is not, what I would call a heavy load.

*the refrigerator and all a/c plugs are in the secondary (inverter) panel and all coming off of one 20 amp breaker, Per Plowjockey!

What is the power requirement of the Microwave?

What is the AR ratting of the battery(s) used to power the inverter?

Rich.

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Do you by any chance have the battery charger connected to the same circuit as the outlets? As in the charger is plugged into one of them OR it's wired to that circuit? If so, that can create all kinds of problems - you'll be drawing power from the batteries to feed the inverter, and then the inverter is sending it back to the batteries.

Also, if that is truly 5.5 amps at 120vac would equal 55 amps being drawn from your battery bank to run the refrigerator. That is a large enough load to pull the batteries down quickly.

Why the need to run the fridge off the inverter in the first place? Typically that's done when one has a residential fridge since they need 120v at all times to operate. The fridge we're talking about here will probably be much more efficient with regard to electrical demand if it's run on propane. Then it will only be a small 12v power load and much easier to handle on the batteries. I haven't ever heard good things about trying to run a propane/120v fridge on the 120v side through an inverter.

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With an absorption type fridge that is capable of running on propane, why would you want to run this fridge on AC anyway? As Richard says LP is the most energy efficient.

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7 hours ago, plowjockey said:

the refrigerator works on elec and propane, has an ice maker which is inactive.

Did the icemaker work before when running the the refrigerator on propane and not pugged in or on generator? 

Bill

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Want to thank everyone for their insight and willingness to help. I'll go from top to bottom on the responses and try to answer to the best of my ability.  General info:  2008 Safari Simba, bought with 23K and currently has 42K.  Refrigerator is a Norad model 1210im OEM, current under a/c 5.5 amp 660 w,  under d/c 2.7 amps 33w, 2400 BTUH.  Now this rest of info.

*the inverter does not start the refrigerator when shore power is off.  I initiate the start up

*the GFCI is located in the bathroom and supplies all the plugs forward in the coach.  Only the plugs in bedroom come from a different source.   

*thanks for the explanation of the GFCI function.  BTW,  the refrigerator never gets tripped when under shore/generator power.

*I also think its related to start up and causing me to think that I might need a bigger inverter 

*the motorhome came without an inverter.  The inverter was installed  20 months ago.

*the refrigerator is in the coach

*the refrigerator works on elec and propane, has an ice maker which is inactive.

*the refrigerator and all a/c plugs are in the secondary (inverter) panel and all coming off of one 20 amp breaker.  Also, the microwave is  supplied by this line.

*I'm not sure about the elements but would think that if that was the problem, it would also have the same issue under shore power?  

*I unplug that line going to the outlet and nothing happens to the fridge, so I think that's the only source.

I hope all the questions are answered, if not let me know and I'll fill in the blanks.

Thanks again for the help as the way it operates now really limits us.  I know you can't have everything when using an inverter (without spending a fortune) but I would just like lights, plugs, microwave & refrigerator.

 

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I have (4) T105 Trojan 6v (new) rated 225 amp hrs @20 hrs or 185 amp hrs @5 hrs.  Microwave is a Sharp R1870F OEM, 1.60 kw.  Inverter is used very often during four summer months on boondocking  property.   Have used propane but would like to take advantage of solar power (600w of solar panels).  Wife didn't want ice maker so discontinued its use and used extra space in freezer for storage.  No battery charger on that circuit.  Batteries are charged  via  40 amp solar charger.

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If you're trying to find a way to run the fridge while boondocking without using propane, the inverter is not the answer. Those batteries are just not enough to power that thing on electricity. An absorption fridge is going to be an energy hog, regardless of what you do to make it run. The electric options are really only for when you're plugged in or for use a short time while driving.

The best way to get away from the propane would be to convert this refrigerator to run as a 12vdc compressor fridge. This is the place to get the kit: https://jc-refrigeration.com/

They have a good reputation of converting propane fridges to run on 12vdc using a compressor. I've got a 12vdc compressor fridge and it works great, doesn't use much battery, and keeps the ice cream rock hard.

The other option which a lot of people have done is to replace the absorption fridge with a small residential fridge. That works if you have adequate battery capacity and inverter. You've only got about 225 Ah of usable capacity (50% of the 450 Ah your four batteries provides) and that won't last too long powering a fridge if it draws too much.

My compressor fridge draws only 5.7 amps from my 12v battery bank, and only when the compressor runs, which is about half the time. A really good energy efficient residential fridge might pull as little as 1.0 amp, but that will be at 120vac. Your inverter will be pulling 10 amps from your battery bank at 12vdc to make that 1.0 amp though, so it's not as energy efficient as it initially appears.

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