Mini Circuit Breaker Always Pops

Every time I connect or disconnect the RV from the pedestal the Mini circuit breaker pops. I always connect/disconnect with the breakers off. Would it help to change the factory manually resettable 20 amp with a manually resettable 30 amp. I have to check that little breaker constantly to make sure I am charging.

farside291 said:

Every time I connect or disconnect the RV from the pedestal the Mini circuit breaker pops. I always connect/disconnect with the breakers off. Would it help to change the factory manually resettable 20 amp with a manually resettable 30 amp. I have to check that little breaker constantly to make sure I am charging.

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The mini-breaker you refer to is 12 VDC. The other breakers you say you disconnect are 120 VAC. So no linkage there.

I'd start by replacing the 20 amp manual mini-breaker with the same size first. They're about $7 or so. For a backup, pickup a 30 amp manual mini-breaker at the same time.

Are you turning off the main 50 amp 120V AC circuit breakers inside the coach before disconnecting? When you turn the pedestal breaker on and off, you can have electrical spikes on equipment inside the coach. Turning off the pedestal breaker before unplugging protects the pedestal receptacle, not the coach.

As a best practice, before plugging or unplugging, have the main 50 amp breakers inside the coach turned off.

And if you really have a 20 or 30 amp 12V manual reset mini-circuit breaker on the buss bar near the battery, either the factory made a mistake, or the dealer changed it thinking he was fixing some problem. The manual reset breaker should be a 50 amp.

Take a look at our Electrical User Guide and Hydraulic Slide Out Starts and Stops User Guide for more information on the manual-reset 12V circuit breaker.

Dan- following this thread for learning purposes. Where, in general, would the rig’s 50 amp breaker be located?

Mrsfish said:

Dan- following this thread for learning purposes. Where, in general, would the rig’s 50 amp breaker be located?

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You may just have a defective/weak 20 amp breaker. Replace it with the same size, not larger. Replacing with a larger CB that was designed for the circuit is about the same as when my father use to replace a 15 amp edison base (screw-in) fuse with a 30 amp edison base fuse so he wouldn't blow fuses all the time instead of reducing the excessive load he had on his circuit. Or it could be like the outdoor disconnect for an air conditioner I was working on once and the landlord replaced the buse fuses with 1/2" copper tubing.

Just to be clear, a larger amperage CB will not protect a circuit that was designed for max 20 amp use. Using a 30 amp CB could and you could end up with a fire.

Mrsfish said:

Dan- following this thread for learning purposes. Where, in general, would the rig’s 50 amp breaker be located?

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Ann,

There's a row of mini-circuit breakers located near the battery/batteries. They're usually covered by a red rubber boot. The individual breakers are connected by a copper buss bar on one side and have wires going to the other side of each breaker.

I've attached a couple of typical pictures; one with the red rubber boot; others with it pulled out of the way.

On all of the luxury trailers (LM, BH, BC), I'm pretty sure you'll find a 50 amp breaker, not a 20, unless someone made a mistake. The wires to that breaker are pretty thick to handle 50 amp. The attached pictures will give you the idea. New LM 365 units may have an 80 amp breaker. And you may even find an 80 amp on some new BH and BC units.

On smaller trailers, it's possible you might find a 30 amp breaker. The trailer would have to be pretty small and have very little in the way of 12V DC power demand before a 20 amp breaker would do the job.

danemayer said:

Ann,

There's a row of mini-circuit breakers located near the battery/batteries. They're usually covered by a red rubber boot. The individual breakers are connected by a copper buss bar on one side and have wires going to the other side of each breaker.

I've attached a couple of typical pictures; one with the red rubber boot; others with it pulled out of the way.

On all of the luxury trailers (LM, BH, BC), I'm pretty sure you'll find a 50 amp breaker, not a 20, unless someone made a mistake. The wires to that breaker are pretty thick to handle 50 amp. The attached pictures will give you the idea. New LM 365 units may have an 80 amp breaker. And you may even find an 80 amp on some new BH and BC units.

On smaller trailers, it's possible you might find a 30 amp breaker. The trailer would have to be pretty small and have very little in the way of 12V DC power demand before a 20 amp breaker would do the job.

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Ok- got all of this. Have even had the mini pop and had to reset. But where would we turn off the 50 amp inside the trailer if I’m following good protocol?

Thank you everyone for the replies. As for the breaker size, I looked at some of the pictures posted in couple of posts of a mini resettable breaker and assumed it was the same. Just for clarification, I am talking about the breaker with the button on the side. I will start turning off the house breakers before plugging and unplugging.

Mrsfish said:

Ok- got all of this. Have even had the mini pop and had to reset. But where would we turn off the 50 amp inside the trailer if I’m following good protocol?

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Inside the trailer you've got a main circuit breaker panel. There are 2 50-amp breakers tied together. Those are the mains. Page 13 of the Electrical User Guide has a nice picture of the breaker panel that you'll find on LM/BH/BC. On smaller trailers, the breaker panel may have the main 50s in the center rather than on the left side.

danemayer said:

Inside the trailer you've got a main circuit breaker panel. There are 2 50-amp breakers tied together. Those are the mains. Page 13 of the Electrical User Guide has a nice picture of the breaker panel that you'll find on LM/BH/BC. On smaller trailers, the breaker panel may have the main 50s in the center rather than on the left side.

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thank you. So these 2x50 amp breakers are what should turned off before plugging into or unplugging from the pedestal..

danemayer said:

Are you turning off the main 50 amp 120V AC circuit breakers inside the coach before disconnecting? When you turn the pedestal breaker on and off, you can have electrical spikes on equipment inside the coach. Turning off the pedestal breaker before unplugging protects the pedestal receptacle, not the coach.

As a best practice, before plugging or unplugging, have the main 50 amp breakers inside the coach turned off.

And if you really have a 20 or 30 amp 12V manual reset mini-circuit breaker on the buss bar near the battery, either the factory made a mistake, or the dealer changed it thinking he was fixing some problem. The manual reset breaker should be a 50 amp.

Take a look at our Electrical User Guide and Hydraulic Slide Out Starts and Stops User Guide for more information on the manual-reset 12V circuit breaker.

Click to expand...

I don't understand the spiking potential difference whether first opening the coach breakers or first opening the pedestal breakers. Either way you are opening the ac feed to the coach. Never experienced any problems just opening the pedestal breakers.

TedS said:

I don't understand the spiking potential difference whether first opening the coach breakers or first opening the pedestal breakers. Either way you are opening the ac feed to the coach. Never experienced any problems just opening the pedestal breakers.

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Now that you raise the question, I was thinking more about effect on the transfer switch. If the mains inside the coach are on when you switch the pedestal on, the power draw from loads inside the coach may cause arcing at the transfer switch contactors as they close. Or at least some of us believe that to be the case.

Is it possible that there's a difference to the Power Converter between closing the circuit at the pedestal and closing the circuit at the main breaker panel - perhaps not.

danemayer said:

Now that you raise the question, I was thinking more about effect on the transfer switch. If the mains inside the coach are on when you switch the pedestal on, the power draw from loads inside the coach may cause arcing at the transfer switch contactors as they close. Or at least some of us believe that to be the case.

Is it possible that there's a difference to the Power Converter between closing the circuit at the pedestal and closing the circuit at the main breaker panel - perhaps not.

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All relay's and contactor contacts bounce when switched. So if power is present, there is arcing. For DC circuits using a relay, a resistor and capacitor connected in series is added across the contacts which used to eliminate the arc. Values are dependent on the current drawn through the contacts.

I must be missing something. Why turn off the breakers inside the trailer before connecting shore power? I have never done that and what exactly is causing the so called spiking? I am not aware of anything in the 12v system that would create that kind of back EMF that would trip that 50 amp breaker. On my trailer the circuit breaker that is for the battery converter is 50amp while the converter is capable of 80 amps. My breaker will trip when the charger is producing more than 50 amps which happens when I am connected to shore power when the batteries require full charge and I am using a lot of 12 power for the slides. I think Heartland is cutting corners by installing 50 amp breakers on an 80 amp converter.

BTY I believe that the transfer switch contacts are normally closed when hooking up shore power so how are they arcing and what has that got to do with the 12v 50 amp converter circuit breaker? And for safety reasons it is a good idea to turn off the campground pedestal breakers when connecting and disconnecting shore power.

With a good surge protector like the PI unit, it has a delay power up while it looks at the shore power. Also with turning off the pedestal first, the PI should handle any spike.

Circuit breakers are not meant to be switches. They wear out with repeated switching on and off. So wear out the one on the pedestal not the one in your trailer.

EVERYONE with 50 amp service should have a good surge protector that shuts off if neutral is lost. I think hardwired ones are the only way to go with trailers that have power cord reels, which could loose neutral.

OP most likely has a weak 50 amp circuit breaker has Dan pointed out. Chris

Let's assume that the OP's problem description is accurate, which is what I'm doing. That leads me to ask how the 50 amp 12V manual-reset mini-circuit breaker can be interacting with shore power. With a few model exceptions, the interaction is the Power Converter. At one end, shore power 120V AC goes in. At the other end, 12V DC comes out and flows to the mini-circuit breaker. So I'm thinking there's something either wrong with the Power Converter, or since it happens when applying power at the pedestal, something that happens to the Power Converter when applying power. Or maybe a bit of both.

Other theories are welcome, along with suggestions for the OP on how to mitigate the problem.

As for the transfer switch, I think if you look further, you'll find that the Progressive Dynamics PD52 manual says: "When power is applied to the shore side, the contactor activates and supplies power to the panel." The contactors operate and hold only when the circuit board inside senses correct voltage on L1. When voltage drops below about 105V, the contactors break contact to prevent damage to your trailer from low voltage. I believe that's the case for either generator power or shore power. So I don't think the contacts are normally closed.

The converter may be the problem throwing a surge current when shore power is first applied. That doesn't make sense on disconnect, though; I don't know of an inductive load in the converter that would backlash like that.

Those who are not trained in electronics should not play theorists that are not helpful. Most electronics are deeply rooted in mathematics. Circuit breakers trip when there is too much demand for their current rating or the they are failing to handle the designed current. I think the OP should consult a qualified electrician/technician to properly troubleshoot the problem and provide proper advise. Many try to be helpful, but that help turns into confusion or bad advise in many situations.

dave10a said:

Those who are not trained in electronics should not play theorists that are not helpful. Most electronics are deeply rooted in mathematics. Circuit breakers trip when there is too much demand for their current rating or the they are failing to handle the designed current. I think the OP should consult a qualified electrician/technician to properly troubleshoot the problem and provide proper advise. Many try to be helpful, but that help turns into confusion or bad advise in many situations.

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I only have around 130 weeks of electronics and network training from the USCG, NCR and the Bank I worked for later in life. So I will stand down with one final statement. The Circuit breaker in question is between the converter and the battery bank. I do not know how anyone would think or know that it tripped when power went away. They are known to sometimes have issues when the converter "kicks" on however for three or so reasons. 1. It is weak. 2. The converter has an issue. 3. Batteries have an issue. 4. It was not sized correctly for the converter output. The last one could be from someone replacing the converter with one that has a higher amp DC output rating or an OEM issue of not sized correct.

OK, now I stand down.

Chris

danemayer said:

As for the transfer switch, I think if you look further, you'll find that the Progressive Dynamics PD52 manual says: "When power is applied to the shore side, the contactor activates and supplies power to the panel." The contactors operate and hold only when the circuit board inside senses correct voltage on L1. When voltage drops below about 105V, the contactors break contact to prevent damage to your trailer from low voltage. I believe that's the case for either generator power or shore power. So I don't think the contacts are normally closed.

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It depends on which Transfer switch is used: When my generator is in use I always hear a thud from the relays kicking in, but I hear nothing when connecting to shore power. I don’t know which transfer switch I have. It is better to have a high power relay contacts normally closed before applying power to prevent contact arcing. If the 5200/5300 series are closing contacts while power is applied at the contacts, I question the reliability and longevity. Both models could have a relay control circuit that cuts out the power if it falls below 105ac rms.

From the manufacturers manuals:
The 5200/5300:
 When power is applied to the shore side, the contactor activates and supplies power to the panel.
 When power is applied to the Gen side there is a 20-45 second delay then the Gen side contact will activate, power will go to the panel from the Gen side and the shore side will be locked out.
 If shore power returns while the Gen power is present, nothing will happen.
When the Gen power is removed the contactor will drop out and allow the shore side to supply power.
 Generator overrides shore power.
 In a single leg application the HOT1 side must be used for the control circuitry to work.
The 5100 series:
 When the shore power is applied the relay is at rest and power is transferred to the panel.
 When Generator power is applied there is a 20-45 second delay and then the relay activates transferring Generator power to the panel.
 If shore power returns while the Gen power is present nothing will happen.
When the Gen power is removed the relay will drop out and allow the shore side to supply power.
 Generator overrides shore power.