120 Volt Breaker Issue

[trailrider]

Two breakers in the equation. 15 amp breaker runs the refrigerator outlet. Another 15 amp breaker runs the microwave. The refrigerator breaker trips occasionally when running the microwave. Messed around with the breakers and here is where it gets weird. The refrigerator breaker feeds the microwave breaker somehow. If the refrigerator breaker is off, the microwave breaker doesn't supply power to the microwave when you flip the breaker on. How is this even possible?

[trailrider]

westend wrote:
Since this is a subpanel you're working with, it also involves the main load center and associated breakers in that box. The sub panel breakers and associated circuits may be connected to the same bus or circuit in that main load center.

One breaker may also be back fed by the other if there is a junction box or device box where they are connected together.

No to all that. You need to go back and read my previous posts.

[westend]

Since this is a subpanel you're working with, it also involves the main load center and associated breakers in that box. The sub panel breakers and associated circuits may be connected to the same bus or circuit in that main load center.

One breaker may also be back fed by the other if there is a junction box or device box where they are connected together.

[trailrider]

trailrider wrote:

enblethen wrote:
Look for the larger #10 wire coming from the shore power cord. Many go to the screw terminal on a 30 amp breaker. This feeds the rest of the breaker via the buss work.
The screw terminals on the 15 amp breakers feed the device/receptacle.
I am guessing that some one replaced the 30 amp breaker with a fifteen amp.

This post got me to thinking. On this rig the subpanel has the 30 amp inverter input breaker on the far left, then the 15 amp refrigerator breaker, a couple more 15 amp breakers for various things, the microwave 15 amp breaker and one more 15 amp breaker far right.

See if this scenario makes sense. This is me guessing what might be the problem, [COLOR=]the rig is not available for me to look at anymore

The input wire from the inverter and the refrigerator wire are hooked backwards. So the input from the inverter is actually hooked to the 15 amp refrigerator breaker and supplies the rest of the breakers on the panel. I never thought to check the other circuits to see if they are all dead if the refrigerator breaker is off. He only mentioned the microwave being dead after the refrigerator breaker tripped.

Bump

[wa8yxm]

I have wired my fridge so I can choose to run off inverter.... Or not.. Turns running it off inverter is more power (350 watts) than the engine delivers so the batteries run down.. Who'd a thunk it.

Of course there are some outlets that I do want on the inverter from time to time so when I want power to them. I force the Fridge to GAS and flip the selector switch (30 amp tansfer) and it ..> Transfers.

[trailrider]

enblethen wrote:
Look for the larger #10 wire coming from the shore power cord. Many go to the screw terminal on a 30 amp breaker. This feeds the rest of the breaker via the buss work.
The screw terminals on the 15 amp breakers feed the device/receptacle.
I am guessing that some one replaced the 30 amp breaker with a fifteen amp.

This post got me to thinking. On this rig the subpanel has the 30 amp inverter input breaker on the far left, then the 15 amp refrigerator breaker, a couple more 15 amp breakers for various things, the microwave 15 amp breaker and one more 15 amp breaker far right.

See if this scenario makes sense. This is me guessing what might be the problem, [COLOR=]the rig is not available for me to look at anymore

The input wire from the inverter and the refrigerator wire are hooked backwards. So the input from the inverter is actually hooked to the 15 amp refrigerator breaker and supplies the rest of the breakers on the panel. I never thought to check the other circuits to see if they are all dead if the refrigerator breaker is off. He only mentioned the microwave being dead after the refrigerator breaker tripped.

[Chris_Bryant]

Normally, coaches have inverter outlets for the ice maker , and will have a non-inverter outlet for the fridge itself.

[MrWizard]

trailrider wrote:
It is a 30 amp sub panel fed from the inverter. I already took the cover off and verified that each breaker is wired to it's own separate romex. Once those romex leave the box I have no idea what happens down the line.

Previous owner added sub panel and inverter
And tied it to pre-existing fridge circuit

My guess is he never used 120v for fridge
This left the circuit available for the MW when using generator or inverter

Check wire size on the primary 15 amp breaker that trips
If it is 12ga wire, you can replace that breaker with a 20 amp breaker

[enblethen]

It would be nice to know the make and model of the rig on first posting.

[DrewE]

Obviously something is wired wrongly, but you know that already.

The 30A breaker from the inverter--does it really and truly go to the inverter (or its associated transfer switch)?

I would have guessed that the two-way fridge would be one thing that should not be run from inverter power typically. A residential compressor fridge is, of course, a different matter altogether. I would probably tackle this problem by removing all power from the system, turning off all the breakers, and using a meter or signal tracer figure out exactly what is connected to each of the breaker outputs. It might be a bit of a forensic search.

[wa8yxm]

Sounds to me like a couple wires in that Sub Panel are crossed (that is hooked up wrong)

NOTE: Caution, you will be working with HOT wiring, SHOCK hazard, Take precautions or get someone who knows what the blazes he's doing (IE: ME) to do these tests... I also have the hardware.

how to test, You need a 120 volt test light or multi-meter. I like test lights cause they are "Quick and dirty"

Turn off ALL breakers in the box.. One probe to the white wire bus You can even screw it down if you like (makes it easier to do this test)

now probe the black wires

IF any wire connected to a breaker is "hot" that is your problem NO breaker wires shoudl be HOT

There is also supposed to be a black wire hooked to a bus bar.. The bar the breakers connect with (A black wire not connected to a breaker) This one SHOULD be HOT. if it' snot, your box is mis-wired.

If you are in S.E. Ga.. So am I.

[time2roll]

OK and somehow they are cross connected to act the way they do.
Start disconnecting something and checking where the power flows.

Should be easy if these are dedicated circuits. If they serve multiple outlets they may need to get mapped and wire connections checked at each point.
Systematic elimination will find the issue but have to start separating things.

[trailrider]

time2roll wrote:
So it is a two pole breaker and each has separate romex.....

Any chance the microwave and fridge are plugged into top and bottom of the same duplex outlet?

I would remove both romex (hot) and verify power and breaker function with a multimeter or voltage detector. Post the results but I think it will check OK. Then attach one romex to one breaker and see if it back feeds on the other romex. Then swap and check the other direction. Post the results.

Need to divide and concur. Test each section separated from others. Otherwise it is just a swirling mystery.

No two pole breakers in this panel. Each appliance has it's own outlet on different sides of the motorhome.

[time2roll]

So it is a two pole breaker and each has separate romex.....

Any chance the microwave and fridge are plugged into top and bottom of the same duplex outlet?

I would remove both romex (hot) and verify power and breaker function with a multimeter or voltage detector. Post the results but I think it will check OK. Then attach one romex to one breaker and see if it back feeds on the other romex. Then swap and check the other direction. Post the results.

Need to divide and concur. Test each section separated from others. Otherwise it is just a swirling mystery.

[enblethen]

Not on the Komfort, was on visiting rig. Correct?
Sounds now like it is a loose or open neutral on a fifty amp rig.