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Old 08-09-2022, 07:51 PM   #1
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circuit breaker overheat 34HD

2020 34 HD rear a/c unit tripping breaker
weather very hot
this breaker is a double unit with the dryer on 1 side
front ac has a larger single unit breaker
I proped the c/b box door open and put a small fan blowing in to cool the box
worked for 3 days @ 108 degrees
made it to cooler weather
will invent blower for this area
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Old 08-09-2022, 08:49 PM   #2
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Quote:
Originally Posted by Joe B View Post
2020 34 HD rear a/c unit tripping breaker
weather very hot
this breaker is a double unit with the dryer on 1 side
front ac has a larger single unit breaker
I proped the c/b box door open and put a small fan blowing in to cool the box
worked for 3 days @ 108 degrees
made it to cooler weather
will invent blower for this area
Please turn of shore power then Check and make sure the wire is tightly screwed into. A loose screw or wire will cause it to get hot. Also make sure the breaker is seated in the panel.. if it still gets hot I would replace the breaker.
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Old 08-09-2022, 09:39 PM   #3
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will invent blower for this area
You are treating the symptom of the problem and not the problem itself. Circuit breakers normally don't get hot on their own, there is a problem causing them to get hot.
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Old 08-09-2022, 09:42 PM   #4
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Quote:
Originally Posted by Joe B View Post
2020 34 HD rear a/c unit tripping breaker

weather very hot

this breaker is a double unit with the dryer on 1 side

front ac has a larger single unit breaker

I proped the c/b box door open and put a small fan blowing in to cool the box

worked for 3 days @ 108 degrees

made it to cooler weather

will invent blower for this area
What RV brand is a 34HD?
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Old 08-10-2022, 04:37 PM   #5
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A little heat is normal

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You are treating the symptom of the problem and not the problem itself. Circuit breakers normally don't get hot on their own, there is a problem causing them to get hot.
Umm, little heat when operating near the rated load will normally cause a breaker to get warm or hot. I spent a summer designing building wiring and part of the job was to specify breaker to be used.

These breakers are designed with two distinct trip mechanisms for two distinct conditions in order to provide protection while minimizing nuisance tripping.
  1. Moderate overcurrent (e.g., 110-150% of rating): The breaker includes a series resistance which warms a thermal release (bi-metallic?) which trips the breaker. Specifications may include details like "several minutes at 110%, 10 seconds at 200%). This prevents tripping from motor-starting currents (A/C, refrigerator) that momentarily exceed rating. This resistance warms the breaker and its case.
  2. Severe overload (short circuit or nearly so): The breaker also includes a series electromagnet. Its strength under moderate currents is not sufficient to trip the breaker, but under a heavy overload the electromagnet will trip the breaker.
Now, Commander, it's obvious that one would be able to feel the warmth of any breaker operated near rated load. (Try it on your water heater breaker.) And it's also obvious that the trip point is affected by the cumulative effect of internally generated heat and ambient temperature. The OP's breaker could be old and have a reduced thermal trip point, but when you consider the effect of an additional 40F temperature, it might be performing to specification.

(Last Wednesday, we opened up the trailer. Outside air temperature was 90F. Inside the trailer it was 109F. When you consider that the breaker was probably spec'd at 20C (68F), a difference of 41F. The internals of the breaker were probably hot enough to burn me after the A/C ran for a while--and this is NORMAL operation. There's a reason why breakers are packaged in Bakelite. When I think about it, I'm actually pleased that the air conditioner started.)
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Old 08-10-2022, 06:08 PM   #6
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Umm, little heat when operating near the rated load will normally cause a breaker to get warm or hot. I spent a summer designing building wiring and part of the job was to specify breaker to be used.

These breakers are designed with two distinct trip mechanisms for two distinct conditions in order to provide protection while minimizing nuisance tripping.
  1. Moderate overcurrent (e.g., 110-150% of rating): The breaker includes a series resistance which warms a thermal release (bi-metallic?) which trips the breaker. Specifications may include details like "several minutes at 110%, 10 seconds at 200%). This prevents tripping from motor-starting currents (A/C, refrigerator) that momentarily exceed rating. This resistance warms the breaker and its case.
  2. Severe overload (short circuit or nearly so): The breaker also includes a series electromagnet. Its strength under moderate currents is not sufficient to trip the breaker, but under a heavy overload the electromagnet will trip the breaker.
Now, Commander, it's obvious that one would be able to feel the warmth of any breaker operated near rated load. (Try it on your water heater breaker.) And it's also obvious that the trip point is affected by the cumulative effect of internally generated heat and ambient temperature. The OP's breaker could be old and have a reduced thermal trip point, but when you consider the effect of an additional 40F temperature, it might be performing to specification.

(Last Wednesday, we opened up the trailer. Outside air temperature was 90F. Inside the trailer it was 109F. When you consider that the breaker was probably spec'd at 20C (68F), a difference of 41F. The internals of the breaker were probably hot enough to burn me after the A/C ran for a while--and this is NORMAL operation. There's a reason why breakers are packaged in Bakelite. When I think about it, I'm actually pleased that the air conditioner started.)
Well, put a fan on it then, I guess. I've never heard of a standard AC distribution panel with nothing but circuit breakers in it require a cooling fan.
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Old 08-10-2022, 07:04 PM   #7
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Keep cool

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Well, put a fan on it then, I guess. I've never heard of a standard AC distribution panel with nothing but circuit breakers in it require a cooling fan.
Standard panels don't usually operate at close to rated load at 109 degrees F.

If this happened to me in the field, I would turn off everything else (to minimize current through the breaker), then run the A/C until the interior cooled down.
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Old 08-10-2022, 08:23 PM   #8
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Standard panels don't usually operate at close to rated load at 109 degrees F.

If this happened to me in the field, I would turn off everything else (to minimize current through the breaker), then run the A/C until the interior cooled down.
Thank you for the information. From some research it looks like circuit breaker rated capacities are based upon 104F ambient temperature. Lower than 104F and the tripping point goes up. Higher than 104F and the tripping point does indeed go lower than what the circuit breaker is rated for. And then on top of that, there is the allowed tolerance.
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Old 08-10-2022, 09:01 PM   #9
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Smile Hot Breaker

I use an Infra Red heat gun to locate the hot breaker. The Infra-Red measures temperature without touching.

Bob
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Old 08-10-2022, 09:32 PM   #10
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I have a simple diagnostic, what is he Amp rating of the circuitbreaker, what is the actual circut voltage and Amp draw.


I learned alot from this posting. Oh by the way, Bob I like to test the temperature with my tongue :-]
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Old 08-15-2022, 06:42 AM   #11
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Circuit breaker

Connections have been checked nothing loose
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Old 08-15-2022, 06:45 AM   #12
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Dynamax super C
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Old 08-15-2022, 07:14 AM   #13
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did anyone measure the actual voltage and amps.... start from the post

at the power post
at breaker box input
at breaker box individual breakers.
at the a/c input
at the a/c individual components (especially the compressor)


Multi meters are a great tool, last forever and are great in tracking down problems without paying big $$$ replacing parts that you think may be faulty


Lots of videos on google on how to use a multi meter
you can also google individual problems .. test air conditioner compressor voltage with multi meter
even if a tutorial is NOT based on a RV .... the principle is the same so 99% of the info out there can be used in a RV situation
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Old 08-15-2022, 07:23 AM   #14
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Probably the breaker. Not expensive. Not hard to change.

Running like this is not a good plan.
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