Wall Connector getting service main HOT

[Gu$ G]

I have a Tesla Wall Connector that is being used to charge a Signature Model S with dual chargers. The wall connector is on a dedicated subpanel with a 70A breaker, then 2 AWG wire is run to the service panel with a 100A breaker. That service panel and main breaker also provide power to my other subpanel which serves the rest of the house, a small 1000 sqft home with typical appliances.

The 100A main breaker blew after about a week of use when charging at 56A (the highest the Tesla allows when installed on a 70A subbreaker). The main was very hot and after it blew it caused some corrosion and discoloration to the main breaker bars / service lugs that are attached to the meter.

I have become more conscious of our electrical usage and corresponding load to try and prevent this from happening with not much luck. I thought I could charge the car consistently at 40A and still have other appliances running without the breaker tripping. I have a Fluke ammeter and have taken to measuring the voltage at the service main during peak usage and I have never seen it above 50-60A.

Despite replacing the breaker multiple times, new ones continue to last only 3-6-9 weeks and then they trip again. Often, after the breaker trips once, it starts running very hot with even lower electrical load. It has to be replaced each time. I have inspected throughout the house and, as far as I can tell, the heat seems isolated to the service panel. One notable area I havent inspected is inside the wall connector itself, but at no time has the subpanel been hot or the breaker tripped.

I am getting ready to hire someone to replace the load center / service panel. I figure the main bus is damaged and the corrosion I'm seeing where the breaker attaches is causing all this heat.

In the process, hopefully we can upgrade the service a bit in the process. Hawaii offers time of use that drives me to want to charge in the middle of the day, as fast as possible. Having an upgraded service panel would allow me to dual meter my home, time of use for the EV and the rest of the house free of that restriction.

I thought I would see if anyone else has suggestions. Here are a few points to note:

1. I have read that the circuit breakers sold at Lowes/HD are often pretty poor quality and will trip at much lower amperage than rated.
2. The wall connector generates a ton of current and heat when its operating, which stresses any home electrical system.
3. Charging above 40A is particularly demanding. I wonder why my 2012 Tesla was offered with dual chargers and that was later removed?

 

[JasJ]

You need a service panel upgrade. Some panels have been recalled as they failed over time (and not in a good way). Federal Pacific and Zinsco in particular.

 

[user212_nr]

It is not normal for beakers to be damaged by tripping, so the fact that they are indicates some serious and dangerous condition.

It sounds like the system you have now is very dangerous and that you should reduce the number of AMPs that you charge with until you figure out what is wrong.


1. If true seems unrelated to your problem.
2. The heat is managed when properly installed.
3. Its only demanding if you have not the proper equipment. It is demanding for when your limit is 100A, and you take 40 for the car. Yes, it is a lot and far beyond most people's needs.

Circuit breakers have a mechanism that they trip when they get hot, not only when the number of amps is reached. You have 100A main panel and 70A dedicated to your car, so that leaves 30A for running your house. That alone is a huge mistake, irresponsible, and probably illegal, but you also have to consider whether the usages are "continuous".

So if your care uses 56A, that means that you have 44A left before your breaker trips, but that does not take into consideration that the load is continuous. For continuous loads, you have only 80% capacity, that is 80A, with 24A allowed for your home.

No doubt you are often using more than the 24A for your home and so heating up the wires and panel.

If you want to continue charging at 56A, then you need to get upgraded service to 200A. Otherwise, you need to lower the breaker on your charging, and have an electrician do your load calculations and inspect for damages. Since you think the panel is fried, maybe best to upgrade to 200A.

 

[ALSET YXES]

I have a Tesla Wall Connector that is being used to charge a Signature Model S with dual chargers. The wall connector is on a dedicated subpanel with a 70A breaker, then 2 AWG wire is run to the service panel with a 100A breaker. That service panel and main breaker also provide power to my other subpanel which serves the rest of the house, a small 1000 sqft home with typical appliances.

The 100A main breaker blew after about a week of use when charging at 56A (the highest the Tesla allows when installed on a 70A subbreaker). The main was very hot and after it blew it caused some corrosion and discoloration to the main breaker bars / service lugs that are attached to the meter.

Hmm... Questions;

1) What is the total service feed to the house? Just a 100A @ 120/208V?
2) Is the Wall connector wired in single or dual phase?
3) Is the Wall Connector a 2012 model?

If you only have 100A service feeding to your home and you have a sub panel with a 70A breaker then at times you are clearly maxing out your total service feed thus blowing the main breaker.

I would imagine that you also have AC in the home? If so that alone running while your car is charging is enough to overload and pop the main breaker.

My recommendation is to request a service feed update from the Hawaii Electric to 200A @120/208 service. Their feeder lines may already have the capacity to provide 200A @ 120/208 in which case you would just need to replace your main panel with a 200A rate panel. At the same time replace the sub panels 70A breaker with an 80A so you can charge at 72A max as you have dual on board chargers. Not needed but nice to have.

I thought I would see if anyone else has suggestions. Here are a few points to note:

1. I have read that the circuit breakers sold at Lowes/HD are often pretty poor quality and will trip at much lower amperage than rated.
2. The wall connector generates a ton of current and heat when its operating, which stresses any home electrical system.
3. Charging above 40A is particularly demanding. I wonder why my 2012 Tesla was offered with dual chargers and that was later removed?

1) All breakers have to meet UL listing minimums but given the age and heavy use this breaker was has seen I am not surprised it's damaged.
2)Yes, if the service feed is only 100A @ 120/208V then you have been maxing out your service feed every time you charge your car.
3)Tesla primarily provided dual on board charger options due to limited changing options between 2012-2016 and to provide a faster charge (50% faster) for those who wanted it.

Hope that is helpful!

#ChargeOn

 

[Gu$ G]

Very helpful guys, thank you.

I'll put more detail into a reply shortly. The service being provided is a 100A @120/208V. I called Hawaiian Electric and they said I was safe to upgrade to a 125A main breaker but that a new line would be required to upgrade the panel to 200A.

I'm going to pursue the upgraded panel and until then limit my charging on the Tesla. Nevertheless, I appreciate the discussion and insight. I'm not trying to do anything borderline or unsafe.

I do not have any HVAC or AC (since the house is in Hawaii!) and the typical electrical load of my house rarely exceeds 30A without charging. Nevertheless, I concur with everyone's assessment that 56A continuous to charge the Tesla was unrealistic. I'm limiting the car to 30A for now, as well as limiting appliances in use, until I get more data. I've also upgraded the main breaker and cleaned the corrosion on the breaker bus bars.

 

[Gu$ G]

Also the service panel is a Arrow-Hart/Murray box, probably from the early to mid-70's.

We're pretty confident the original breaker that failed was very old and already on its way out before the upgrade wall connector. The additional corrosion that failure made on the bus has continued to plague us with replacement breakers. The rest of the service panel looks OK. The right answer definitely seems to be replace the service panel and upgrade the service while I'm at it.

 

[user212_nr]

I do not have any HVAC or AC (since the house is in Hawaii!)

You must be native Hawaiian (or born there at least). We in less-warm climates cannot live without A/C in the warm months. Seriously, I've tried it and I get delirious.

 

[Gu$ G]

You must be native Hawaiian (or born there at least). We in less-warm climates cannot live without A/C in the warm months. Seriously, I've tried it and I get delirious.

No, but we live by the water in Kaneohe and get a great trade wind most of the year. The summer months when the wind dies down can be very difficult. My wife finally got me to buy a window AC unit last summer... she was 8 months pregnant so I caved!

 

[XHabjab]

I have a Tesla Wall Connector that is being used to charge a Signature Model S with dual chargers. The wall connector is on a dedicated subpanel with a 70A breaker, then 2 AWG wire is run to the service panel with a 100A breaker. That service panel and main breaker also provide power to my other subpanel which serves the rest of the house, a small 1000 sqft home with typical appliances.

The 100A main breaker blew after about a week of use when charging at 56A (the highest the Tesla allows when installed on a 70A subbreaker). The main was very hot and after it blew it caused some corrosion and discoloration to the main breaker bars / service lugs that are attached to the meter.

I have become more conscious of our electrical usage and corresponding load to try and prevent this from happening with not much luck. I thought I could charge the car consistently at 40A and still have other appliances running without the breaker tripping. I have a Fluke ammeter and have taken to measuring the voltage at the service main during peak usage and I have never seen it above 50-60A.

Despite replacing the breaker multiple times, new ones continue to last only 3-6-9 weeks and then they trip again. Often, after the breaker trips once, it starts running very hot with even lower electrical load. It has to be replaced each time. I have inspected throughout the house and, as far as I can tell, the heat seems isolated to the service panel. One notable area I havent inspected is inside the wall connector itself, but at no time has the subpanel been hot or the breaker tripped.

I am getting ready to hire someone to replace the load center / service panel. I figure the main bus is damaged and the corrosion I'm seeing where the breaker attaches is causing all this heat.

In the process, hopefully we can upgrade the service a bit in the process. Hawaii offers time of use that drives me to want to charge in the middle of the day, as fast as possible. Having an upgraded service panel would allow me to dual meter my home, time of use for the EV and the rest of the house free of that restriction.

I thought I would see if anyone else has suggestions. Here are a few points to note:

1. I have read that the circuit breakers sold at Lowes/HD are often pretty poor quality and will trip at much lower amperage than rated.
2. The wall connector generates a ton of current and heat when its operating, which stresses any home electrical system.
3. Charging above 40A is particularly demanding. I wonder why my 2012 Tesla was offered with dual chargers and that was later removed?

Besides the comments others have made:
1. You could be experiencing trouble from weird harmonics in either electricity generation or switching power supplies as load or reactive load. The load problems could be on your circuit or a neighbor. Hawaii has a lot of solar generation which generates AC from switched DC.
2. Similar problem with ground loops if your house has multiple grounds (eg. one for your house panel and one in garage or subpanel. You should only have one.
3. Have an electrician check that the screw connections on all circuits are tight, at room temperature as well as after carrying a load. Especially the high load circuits.

 

[ewoodrick]

Do you drive so much that you feel the need to burn your house down?

 

[Unclenapolean]

I am NOT an electrical engineer or licensed electrician. The following information is based on my personal experience with upgrading my service on a house from 60 Amp Fuse Box service to a 200 Amp Breaker Box service and a service installation on a new house I was building. Upgrading your electrical service from 100 Amp to 125 Amp is pretty straight forward. It should involve just changing out the main breaker to a 125 Amp dual throw main breaker, that is providing your service wire can handle the load. The next step up in service would be to a 150 Amp service, which would involve a new service wire from the utility lines to your house, a new meter, a new breaker box, new main breaker and possibly new breakers for your existing circuits. Skip going to 150 Amp service and go straight to 200 Amp. I was going to switch that 60 Amp fuse box service to 150 Amp Breaker service when my electrician explained to me that the service line, and meter are the same for 150 Amp and 200 Amp service, so the cost is the same. The labor to do the work is the same. The only difference is a slightly bigger breaker box and the bigger main breaker at a little more money.
When reading your posts I noted you said your house was built in the 70's. Aluminum wire was used for wiring entire houses for a short time from the 1960s to the mid-1970s during a period of high copper prices In the 70's. Aluminum wire heats up more than copper under the same load. Aluminum wire also requires connectors designed and rated for aluminum wire on any points where the wire connects to outlets, switches, breakers, and other electrical devices. Failure to have these type connectors can result in the wire loosening from the contact point under a condition called "flowing" or "creep" creating a possible short and increased heat. Please see the information on Aluminum wire here.

Aluminum building wiring - Wikipedia

You also mention corrosion on contact point. Most metals (with a few exceptions) oxidize freely when exposed to air. Aluminum oxide is not an electrical conductor, but rather an electrical insulator. Consequently, the flow of electrons through the oxide layer can be greatly impeded creating resistance which creates heat.

Please have your electrical system inspected for Aluminum wire by a licensed electrician and/or an electrical engineer.

 

[ewoodrick]

I am NOT an electrical engineer or licensed electrician. The following information is based on my personal experience with upgrading my service on a house from 60 Amp Fuse Box service to a 200 Amp Breaker Box service and a service installation on a new house I was building. Upgrading your electrical service from 100 Amp to 125 Amp is pretty straight forward. It should involve just changing out the main breaker to a 125 Amp dual throw main breaker, that is providing your service wire can handle the load. The next step up in service would be to a 150 Amp service, which would involve a new service wire from the utility lines to your house, a new meter, a new breaker box, new main breaker and possibly new breakers for your existing circuits. Skip going to 150 Amp service and go straight to 200 Amp. I was going to switch that 60 Amp fuse box service to 150 Amp Breaker service when my electrician explained to me that the service line, and meter are the same for 150 Amp and 200 Amp service, so the cost is the same. The labor to do the work is the same. The only difference is a slightly bigger breaker box and the bigger main breaker at a little more money.
When reading your posts I noted you said your house was built in the 70's. Aluminum wire was used for wiring entire houses for a short time from the 1960s to the mid-1970s during a period of high copper prices In the 70's. Aluminum wire heats up more than copper under the same load. Aluminum wire also requires connectors designed and rated for aluminum wire on any points where the wire connects to outlets, switches, breakers, and other electrical devices. Failure to have these type connectors can result in the wire loosening from the contact point under a condition called "flowing" or "creep" creating a possible short and increased heat. Please see the information on Aluminum wire here.

Aluminum building wiring - Wikipedia

You also mention corrosion on contact point. Most metals (with a few exceptions) oxidize freely when exposed to air. Aluminum oxide is not an electrical conductor, but rather an electrical insulator. Consequently, the flow of electrons through the oxide layer can be greatly impeded creating resistance which creates heat.

Please have your electrical system inspected for Aluminum wire by a licensed electrician and/or an electrical engineer.

Yes, it is obvious that you aren't an electrician. Increasing a main breaker, just because you want more, and assuming that there are no issues is recipe for a fire. And if the insurance company finds it out, possible denied claims.

There are a LOT more things that need to be determined

• Can the shared transformer support it
• Can the service wire support it (yes, you did mention this, after the breaker, should always be before)
• Can the meter support it
• Can the panel support it
• Are there upstream panels in the flow

Going to 200A is going to probably fail all of these items. And the power company may not even allow it if the transformer is too small. Older house become a factor as well, as there is degradation that comes into play.

And, for pretty much all of this, permits will probably be required with multiple inspections. You may get away with changing a branch breaker, but not the main.

 

[XHabjab]

...
Please have your electrical system inspected for Aluminum wire by a licensed electrician and/or an electrical engineer.

It should be done by an electrician.
I'm an electrical engineer. I'm a guy that potentially designs the equipment that the electrician installs but I'm not qualified to do an installation (except on my own residence). An electrician will know about universal and local electrical code that the engineers wrote. Electrical code changes and expires like the cheese in your fridge.

It's a little like the difference between an athlete and a coach.

 

[Unclenapolean]

Yes, it is obvious that you aren't an electrician. Increasing a main breaker, just because you want more, and assuming that there are no issues is recipe for a fire. And if the insurance company finds it out, possible denied claims.

There are a LOT more things that need to be determined

• Can the shared transformer support it
• Can the service wire support it (yes, you did mention this, after the breaker, should always be before)
• Can the meter support it
• Can the panel support it
• Are there upstream panels in the flow

Going to 200A is going to probably fail all of these items. And the power company may not even allow it if the transformer is too small. Older house become a factor as well, as there is degradation that comes into play.

And, for pretty much all of this, permits will probably be required with multiple inspections. You may get away with changing a branch breaker, but not the main.

Apparently you missed the part where Nomar 116 said, and I quote, " I called Hawaiian Electric and they said I was safe to upgrade to a 125A main breaker but that a new line would be required to upgrade the panel to 200A." And it seems that based on that quote, Hawaiian Electric considered the transformer capable of handling the increased load.

You also missed where I said 200 Amp service requires a new service line, a new meter, a new main breaker box (aka panel), new main breaker and possibly new branch breakers. I was responding to Nomar 116's discussion about upgrading his main electrical service, so there would be no "upstream panels".

I also thought it too obvious to need to point out that the work would be getting done by a licensed electrician, which would require permits to be pulled.

Guess you were just looking to pick at something.

 

[Unclenapolean]

It should be done by an electrician.
I'm an electrical engineer. I'm a guy that potentially designs the equipment that the electrician installs but I'm not qualified to do an installation (except on my own residence). An electrician will know about universal and local electrical code that the engineers wrote. Electrical code changes and expires like the cheese in your fridge.

It's a little like the difference between an athlete and a coach.

Thanks for the clarification, XHajab.

 

[ewoodrick]

Apparently you missed the part where Nomar 116 said, and I quote, " I called Hawaiian Electric and they said I was safe to upgrade to a 125A main breaker but that a new line would be required to upgrade the panel to 200A." And it seems that based on that quote, Hawaiian Electric considered the transformer capable of handling the increased load.

You also missed where I said 200 Amp service requires a new service line, a new meter, a new main breaker box (aka panel), new main breaker and possibly new branch breakers. I was responding to Nomar 116's discussion about upgrading his main electrical service, so there would be no "upstream panels".

I also thought it too obvious to need to point out that the work would be getting done by a licensed electrician, which would require permits to be pulled.

Guess you were just looking to pick at something.

Or maybe I missed the reply way down in the thread