Breaker and ambient temperature

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Alex800st

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charging my clarity at Rv park. Breaker on the site is 30 amps, but trips often. With clamp meter I checked the load - never above 20a.
I suspect that breaker sits in a small electrical box that is located in a sunny area, and it gets hot.
But I could not find a table that would show how hot 30a breaker should be to trip at 20a.
Any ideas?
 
You could replace breaker, but that probably won’t fix the problem.

I gotta ask were you staring at your meter AT THE MOMENT it tripped? If not you don’t know that the load is not exceeding 30 amps at times. It might be. So better yet troubleshoot the circuit with ohm meter and with visual checks of all connections at plug and breaker. In my experience breakers rarely fail...so it might be just doing its job because there is an intermittent short somewhere, and sometimes shorts only occur under load with some heat buildup. So if you are not the electrical maintenance guy, then report the problem to park owner so they can troubleshoot it, or just move to a different circuit at the park and try charging there to rule out your charger as causing the problem.
 
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Industry standard : https://www.se.com/us/en/faqs/FA173839/
But, and a very big but: A very large number of homes, apartments, and businesses have their main panels on an exterior wall that sits in the sun for most or all of the day. Breaker boxes sitting in the sun are almost assuredly not the problem here. As @craze1cars says, breakers rarely fail with the symptom you're giving. There's far more likely to actually be a problem in the circuit causing it to trip than the breaker going on LSD trips.
 
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Another way of saying what I already said. So far, since going largely full time as an electrician in recent years, 100% of my service calls for “my breaker keeps tripping at random times and needs to be replaced”...and there have been many...

result:

Not one time did I actually replace the breaker. I troubleshot and found the problem that was causing the trip. 100% so far...no lie.

And about 90% of these service calls are on outdoor circuits that are exposed to weather somehow.
 
I have a HW30C 30A Progressive Industries circuit protection hardwired in my camper and I've seen all sorts of crazy things at power pedestals, including breakers tripping with much less than a 30A load. Is there anything else plugged into the pedestal like another campsite or secondary 15A cord plugged in? Anything contributing to heat and load could be a culprit. Can you check to see if the car trips breakers at other campsites?
 
Unfortunately I cannot try another site - it is a permanent location.
Breaker trips (seems likely) only on hot days. That is what makes me think that the ambient temperature is the suspect. Google says breakers rated at 40 degrees Celsius. So logically if it is hotter outside it should trip with less current. But how much less is the mistery.
Looks like I need a clamp meter that can record spikes, just to be sure there are no spikes.
 
RV Park power can be questionable.

Last we heard you were using an extension cord, or going to fabricate one. Is that still the case?

Are you using the Level 1 device?

Who has been resetting the breaker, since you do not know the location?

Breakers are typically located at the pedestal.
 
@Alex800st, after researching a bit more it seems your theory is possible. I have not run into it yet so new to me, but 40C is only 104 degrees F -- seems breakers installed in hotter locations than that, or in direct sun, may need to be derated in ampacity. It is true that many breakers are rated for only 40C ambient. Should be labeled somewhere on whatever breaker you have, but may need to be pulled in order to find the temp rating -- often molded into the side of the breaker and not on the face you can see when installed. I don't know what brand or style you're using.

You may need to reduce your amp draw during charging by using a lower amp charger, or talk the RV park into replacing the breaker with one that has a higher ambient temp rating to see if it helps. I found some further discussion about your 40C ambient rating that is leading me to think you might be onto something with your temp theory. This forum is mostly made up of professional electricians who discuss all things electrical...I use it as an occasional resource:
https://forums.mikeholt.com/threads/40-degree-c-circuit-breakers.59560/
 
@Alex800st -
Maybe I missed it, but please clarify whether this is a Level 1 (120V) or a Level 2 (240V) charging scenario. Also, are you using the OEM charger that came with the car, or something else? Are you certain that there are no other loads on this circuit? How are you attaching the clamp-on meter (normally, there is no access to just one of the conductors unless you have a specialized adapter or similar)? If this is 240V, the Clarity will draw 30 amps if the EVSE allows it to... Maybe your clamp-on meter is deceiving you and you are drawing more than you think.

The temperature theory is indeed plausible too. The heavy (and 'continuous') load will cause self-heating of the breaker yielding temperatures above and beyond just the ambient condition.
 
EBD5E302-4E15-4230-91CD-E642F408E87E.webp FF3D8515-65AC-43AA-A1A8-A0FD005FB25E.webp On a hot day when I use a/c breaker trips without any extra load (no clarity charging, I kill all the lights, fridge, etc). My measurement yesterday showed that a/c eats only 12a - but this is enough to trip 30a.
Looked at the breaker, indeed it says on the side 40 celsius.
Will measure temperature inside the breaker box today, will be hot here.
On the pic is the load when I have a/c plus all other load in the trailer. (No car charging).
My breaker is the green one on the left.
 
The AC draws more current on start up. There are “soft start” devices available that will prevent the breaker from tripping.

However, a 15,000btu AC, if that’s what you have, should not trip a 30A breaker.
 
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Do you own this box? And are you an electrician? It seems to me from your questions and comments that the answer is likely no to both. That appears to be single phase? Based on 1 wire coming out of breaker I'm now assuming this is a 30 amp 120V circuit and this is not a 240V circuit as I had previously assumed from your 30 amp comment. There is just not enough info to go on here for anyone, so my last and most significant piece of advice is to close it up and ask the owner of the box to send an electrician to troubleshoot this issue. You need a proper test equipment and experience in how to use it to troubleshoot RV park wiring, which can be different form residential, to determine what is causing your problem. Sorry I don't have RV park wiring experience so unless I'm on-site with a meter to figure out exactly what kind of power is coming into this box, what gauge the wires all are, and see more clearly how they've distributed it to the outlets, I can’t help further...

My honest suspicion is that you're asking this low amperage box to simply do too much. That is a small box even by RV park standards. Many modern trailers could not run off of that. There is simply not much there to run an entire trailer AND charge your car...I guess one more piece of advice: I'd seriously consider running your Clarity on gasoline if they can't upgrade that service box for you. But upgrading that box is probably going to require major investment of trenching heavier gauge wire from their distribution area all the way to your site...

I've refused to install car chargers for customers in residences with 100 amp service. So I can't recommend even attempting to charge a car from a residence that has 30 amp service...which is what I believe you have here.
 
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Landshark said:
The AC draws more current on start up. There are “soft start” devices available that will prevent the breaker from tripping.
Click to expand...

Yes, forgot to mention - it's tripping after about 10 mins of using a/c, not on start up. That is the reason that I think towards a heat increasing inside the box is the suspect.
Yes, I am electrical engineer by my university education - but is was 40 years ago, I forgot more than I ever knew.
I will build proper separate outlet for car charging after I will fix that issue.
 
One last question I guess. You still haven't advised if you're L1 charging or L2 charging. I have to assume L1 because I don't see any 240v breakers there in your pic:

You have a 20 amp circuit right there in the same box. If you plug your car into that 20 amp circuit instead of the 30 amp, does it charge fine? Same question for your A/C, which I now have to assume is a 110V unit. L1 charging only draws about 12 amps...many people are charging their cars L1 on 15 amp circuits which are common in homes, so you sure as heck don't need a 30 amp circuit to charge a car on 110V, nor do you need it to run a 110V A/C unit on an RV.
 
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I think there could be connection issue(s) within the box itself, and an electrician will likely be needed to sort it out. Poor connections will generate heat and could cause a breaker to trip, and from the looks of the box, it is not weather tight and corrosion could be a factor. They'll probably also correct code violations like the double tap on the red handled breaker.

The Stab Lok breakers (and panels) are also problematic, but usually the issue is failure to trip.
https://www.redbudinspections.com/dangers-of-stab-lok-circuit-breakers/
https://blog.societyinsurance.com/why-you-should-replace-federal-pacific-stab-lok-panels/
 
Has to be L1. A 30A RV service is a single 120V leg that provides 3600 watts of power. There appears to also be a 15/20A duplex outlet at the pedestal.

It also appears to be “vintage” and not the most professional of installations.

I’d also like to know more about the RV. Are there house batteries and an inverter onboard?

It isn’t out of the question that the breaker is not operating properly and needs to be replaced.
 
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Agree with both previous posts. The whole repair could be as simple as tightening one loose screw...

Loose connections cause excess heat when put under high steady load. Heat trips breakers.
 
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craze1cars said:
From what power source?
Click to expand...

Same power source, I’d presume. The lines coming in look to be sufficient to support an additional breaker. There is room for one in the box.

Of course, a request should be made to park management to perform the work and it should be done by a licensed electrician.
 
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