Replaced Charging Station, tripped meter breaker again.

[F150LAQS]

I posted a few weeks back how I'd had my truck in for a heater replacement, charged it at home and the breaker at the meter tripped. Here is the setup. Isolated meter from utility in back of house, used exclusively for truck. it has its own breaker > wiring from this to box in front of house > surge protector(imaged), in front box > 100amp meter(imaged) in front box > fcsp set to 64 amps.

This setup had worked fine through a previous winter, so this was a mystery, with some clues, oddities, and coincidences:

-The entire circuit had been on but unused for almost 3 weeks in temperatures below 0F, its an outdoor setup.
-When I plugged it in after getting truck back from the shop, it seemed to work fine, charging for a few hours before everything stopped at 71% (scheduled to 80%).
-The meter breaker tripped, while the fcsp's breaker (imaged) stayed in the on position. (could a 64a setting gone wrong fail to trip a 100a breaker??) Nobody seems to know exactly why the box breaker won't trip but the meter breaker will.
-the box breaker (imaged) has very weird white coloring on it that an electrician forum said indicated water ingress / condensation on the zinc plated bar
-the truck had just been in for high voltage work - hopefully everything was put back together right and the truck itself wasn't causing the issue.

electrician trip 1: they came out, replaced the breaker, turned the meter breaker back on, i plugged in and everything looked like it was working. sometime later the exact same thing happened. meter breaker tripped, box breaker did not, everything died.

electrician trip 2: i ordered and received a new fcsp. electricians came out, replaced fcsp, replaced breaker again (this time with an 80a instead of 100a because they said it would be better for me if i charged at 64amp which i do), turned everything on, tested it , it looked good, i was charging as they left... less than 30 mins later exact thing happened AGAIN! meter breaker tripped, box breaker stayed on, everything dead.

I suspect the biggest clue of all is the old breaker (imaged). that there may indeed be corrosion and faulty happenings with the zinc bus bar. though the electricians had their tools out and were testing everything. when they first turned on the new fscp, they watched the amperage climb up to just below 80 amps. when they turned it to 64 amps, they watched the amperage climb up to around 60 amps. they were satisfied, everything looked good. now they will have to come back, and more money will be spent. if anyone can provide me some very good chores, checklists, things to make sure they do before they leave this time, it would be much appreciated. if it is a corrosion issue due to moisture or temp differential (sweat) can my outdoor box be upgraded/insulated/heated so it can not do that again the next time we hit sub-zero weather?!

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[Tired Lizard]

Saw another Siemens QP where the metal tie bar looks to have same corrosion as yours.
Interior looked normal.
Siemens qp and qpp compatibility

Since you weren't charging above 80A originally, don't know what would have caused the trip.

For the original 100A CB a sustained over 100A would trip it in about 1000 seconds / 16 minutes per MCB circuit breaker time current curve. https://forums.mikeholt.com/threads/tcc-curve-for-circuit-breaker.2584218/post-2958014

High ambient temperatures are what are usually mentioned in mfgrs. info, not extreme cold.

 

[K6CCC]

I would agree with your electrician that the breaker looks like it got wet. You can also see similar white indication on the black wires below the breaker in your 2nd photo.

It's a little confusing what we're looking at from your description. You have two boxes each with a 100 amp breaker. The photos both show the white "damage" on the breakers, but appear to be the two different boxes. Can you confirm what photo is what and in what order these are (i.e. which one is downstream of the other)?

 

[Heliian]

Sounds like your meter breaker is bad.

Does the meter breaker have a built in gfci?

 

[Maquis]

I would agree with your electrician that the breaker looks like it got wet. You can also see similar white indication on the black wires below the breaker in your 2nd photo.

It's a little confusing what we're looking at from your description. You have two boxes each with a 100 amp breaker. The photos both show the white "damage" on the breakers, but appear to be the two different boxes. Can you confirm what photo is what and in what order these are (i.e. which one is downstream of the other)?

The OP only provided 1 photo.

 

[K6CCC]

The OP only provided 1 photo.

Oops - my error. Did not notice that the second photo was from someone else. Guess that's what I get for scrolling / reading too fast...

 

[Lucky Larry]

Do you have a GFIC type breaker in the meter Base or in the breaker box by your charger? if so you may want to replace them with normal breakers as the FCSP has a built in GFIC and does not need one at the meter base or breaker box by your charger. see the highlighted section in the attached fcp spec sheet.

 

[Maquis]

Do you have a GFIC type breaker in the meter Base or in the breaker box by your charger? if so you may want to replace them with normal breakers as the FCSP has a built in GFIC and does not need one at the meter base or breaker box by your charger. see the highlighted section in the attached fcp spec sheet.

There are no main breakers suitable for use as service equipment that include GFCI protection (that I’m aware of).
The picture of the breaker near the FCSP shows clearly that it‘s not a GFCI.

 

[bmwhitetx]

If I’m reading this right, the only pic is of the breaker that is not tripping. But it has no reason to trip as he has only been using 80A, and then later, 64 amps. Instead some other breaker at the meter is tripping. And there’s no pic of that one.

Would think the question should be why the meter breaker is tripping when the current is well below 100A. Instead his question seems to be why the FCSP breaker is not tripping first, even after changing it to 80A. But again it has no reason to trip.

The answer to me is the meter breaker is faulty or has gfci or something we can’t see since there’s no pic.

 

[Maquis]

If I’m reading this right, the only pic is of the breaker that is not tripping. But it has no reason to trip as he only been using 80, and then later, 64 amps. Instead some other breaker at the meter is tripping. And there’s no pic of that one.

Would think the question should be why the meter breaker is tripping when the current is well below 100A. Instead his question seems to be why the FCSP breaker is not tripping first, even after changing it to 80. But again it has no reason to trip.

The answer to me is the meter breaker is faulty or has gfci.

Or has something causing additional heat such as a loose connection.

 

[kuzzin]

My two cents. There is a resistive connection at the breaker that trips. My GUESS is that the buss, where the breaker connects, is corroded. This should be relatively easy to see when the breaker is removed.

If not maybe you can borrow or rent a thermal imaging device. You should be able to see where it is getting hot (cover removed). Maybe this is something for your electricIan to accomplish depending on your experience.

 

[struckby]

Could also be cut insulation on the wire? Wire heats and expands until it touches a ground and shorts. I'm not an electrician but I have seen this on heat lamps in a restaurant.

 

[bmwhitetx]

Or has something causing additional heat such as a loose connection.

My two cents. There is a resistive connection at the breaker that trips.

Two good points. I will add to my answer above that the focus should be on the breaker that is tripping but add the wiring and terminations between that breaker and the fscp one. May have a high impedance "short" in the circuit that is actually causing high amps at that breaker. Maybe due to water intrusion/corrosion or insulation breakdown or ??.

OP should show a pic of that one.

 

[chl]

I think that your problem might be the Siemens Bolt Shield surge protection on that outdoor box.

Based on what I just looked up...

It looks like it is an indoor type from the QSPD number which if mounted outdoors needs to be in a weather resistant box/panel.

Outdoor ones have an FSPD number.

If things are getting wet, which an electrician told you might be happening, then the outdoor type should be used I believe.

Maybe replacing it with an outdoor type would solve the tripping of the main breaker issue?

This is what AI says, but it sounds right to me - it references a video about trouble shooting, BUT that is only for a qualified electrician to do!!!

"A Siemens Bolt Shield (or bolt-on) breaker typically trips the main breaker due to a dead short circuit (hot wire touching ground/neutral), a severe overload, or a loose connection at the bus bar. Because bolt-on breakers are often used in commercial or high-amperage panels, a fault here can instantly trigger the main, particularly if it's a phase-to-phase short....

Top Reasons for Tripping

• Loose Bus Connection: The bolt-on mechanism may not be fully seated or tightened properly, creating high resistance and heat, which tricks the main breaker into tripping.
• Short Circuit (Direct Fault): A hot wire is touching a neutral or ground wire, often caused by damaged wire insulation, improper wiring, or a faulty appliance.
• Circuit Overload: The total power demand from devices on that specific breaker exceeds its capacity (e.g., 20+ amps on a 20A breaker).
• Faulty Breaker: The Siemens breaker itself may be damaged or defective, causing it to fail to trip internally and allowing the surge to trip the main breaker instead.
• Arc Fault (AFCI/GFCI): If the breaker is an arc-fault type, it may be tripping due to sensitive, loose neutral connections or interference.

Troubleshooting Steps

1. Check for Tightness: Ensure the bolt-on breaker is securely fastened to the bus bar.
2. Unplug Devices: Unplug all devices on that circuit to rule out a faulty appliance.
3. Inspect Wiring: Check for damaged insulation or loose wires in the panel and junction boxes.
4. Test for Short: Use a multimeter to check for continuity between the hot and ground wires..."

 

[chl]

PS: water in the box could cause the short referenced above.

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