How many of you have 100A home service and charge on a 30A circuit?

[Sophias_dad]

Before upgrading my service to 200A, I had the same setup, minus the central A/C. I charged at night at 24A for almost 2 years before the service upgrade. My nighttime load without charging is a couple of amps. I set the car to charge at 11pm. Occasionally the car would start before a load of laundry finished, but I was still well under the limits of the 100A service


You definitely have a main breaker somewhere, you just haven't found it. Maybe at the meter? You can't leave the main service feeders unprotected. I have a single 200A breaker at the meter, with a "main lug" 200A panel. "Main lug panel" = no main breaker in the panel (think a sub panel with the breaker upstream), vs "Main breaker panel" = panel with a main breaker.

Yes, I'm not sure if its required in the latest code, but it seems to be getting more popular to place the main breaker outside near the meter, presumably so that firefighters can flip the switch as soon as they arrive and not worry about any electrical issues in the house.

 

[tga]

Yes, I'm not sure if its required in the latest code, but it seems to be getting more popular to place the main breaker outside near the meter, presumably so that firefighters can flip the switch as soon as they arrive and not worry about any electrical issues in the house.

I've heard rumors it may appear in the next rev of the NEC and that some fire departments won't enter the house unless they know the power is off. I also heard that some fire departments won't pull the meter, and will wait (while the house burns) until the power company arrives to pull the meter. But this is all hearsay.

I wasn't keen on an outside switch (vandals, etc). I thought about putting a small padlock on it (the FD has boltcutters on the truck), but I stopped worrying about it.

 

[compu85]

You definitely have a main breaker somewhere, you just haven't found it. Maybe at the meter? You can't leave the main service feeders unprotected. I have a single 200A breaker at the meter, with a "main lug" 200A panel. "Main lug panel" = no main breaker in the panel (think a sub panel with the breaker upstream), vs "Main breaker panel" = panel with a main breaker.

No. I do not have a main breaker. It's a Wadsworth panel that was put in in the 60s, and apparently there was no requirement for a main. The panel has 2 lower halves, each with a 60a 240v breaker feeding it. So all the 120v loads are under one of the 60 sub mains, but the 2 big 240V loads (30a dryer, 60a EVSE) don't have a main ahead of them. There are fuses after the breaker for the 30a dryer circuit, though.

 

[tga]

No. I do not have a main breaker. It's a Wadsworth panel that was put in in the 60s, and apparently there was no requirement for a main. The panel has 2 lower halves, each with a 60a 240v breaker feeding it. So all the 120v loads are under one of the 60 sub mains, but the 2 big 240V loads (30a dryer, 60a EVSE) don't have a main ahead of them. There are fuses after the breaker for the 30a dryer circuit, though.

Ah, I didn't realize we were talking about an old panel. That's a different story.

 

[boriszima]

I have 100amps main panel. I charge using full 32amp via 14-50 NEMA. 3 week later I come home to find only half of lights work. Go to panel flip all switches back and worth. Nothing. Called electrical, find out main breaker did not trip but half melted, hence half power. Of course my case is isolated. Electrical did warn me to charge at lowest Amps needed to avoid this as with AC running on 40amp breaker I could be close. In short, if one really wants to find out maybe get a killAwatt Device to measure load. He definitely told me not to get HPWC from Tesla to charge at 60 amps as my electrical load setup would not support it.

 

[Kzooman]

I'm in the same boat as the last respondent, have a 100 Amp Main Breaker that has tripped the last 2 nights, when I charged at the UMC max amperage of 32 amps while connected to a dedicated 50 amp electrical range breaker that was unused. The 50 amp breaker gets warm, but the main breaker gets very HOT and eventually tripped. I never measured more than about 36 amps on both legs of the main. I do hear a buzzing sound after the charging starts, and have downgraded the charging to 20 amps for the time being.

 

[Darthbenji]

I have 100A service. Electric dryer, AC, pool pump, water heater and induction stove. Hired an electrician and had it inspected by the municipality. HPWC charging at 48A. Only charge at night though.

 

[Sophias_dad]

Get someone to replace that main breaker, it shouldn't be close to tripping at only 36 amps.

 

[davewill]

I'm in the same boat as the last respondent, have a 100 Amp Main Breaker that has tripped the last 2 nights, when I charged at the UMC max amperage of 32 amps while connected to a dedicated 50 amp electrical range breaker that was unused. The 50 amp breaker gets warm, but the main breaker gets very HOT and eventually tripped. I never measured more than about 36 amps on both legs of the main. I do hear a buzzing sound after the charging starts, and have downgraded the charging to 20 amps for the time being.

I would get someone out pronto, like TODAY. This sounds like an emergency to me. I wouldn't want to charge at ANY amperage if the main breaker is failing that badly.

 

[Big Earl]

I would get someone out pronto, like TODAY. This sounds like an emergency to me. I wouldn't want to charge at ANY amperage if the main breaker is failing that badly.

Agreed. The main breaker could be arcing internally, creating additional heat. This is a potential fire hazard that needs to get addressed immediately.

 

[eprosenx]

I'm in the same boat as the last respondent, have a 100 Amp Main Breaker that has tripped the last 2 nights, when I charged at the UMC max amperage of 32 amps while connected to a dedicated 50 amp electrical range breaker that was unused. The 50 amp breaker gets warm, but the main breaker gets very HOT and eventually tripped. I never measured more than about 36 amps on both legs of the main. I do hear a buzzing sound after the charging starts, and have downgraded the charging to 20 amps for the time being.

I agree with others. This is an urgent matter. Call a licensed electrician.

It could be as simple as a lug needing torqued down on the main feed. A loose connection could be heating up and that heat is conducting into the breaker and blowing it.

Note that there is a good chance you are going to need a new panel if there is damage. Often replacing a breaker in an old panel is just not worth it. Panels really don't cost that much, but labor can be expensive.

EV's will find any weakness in an electrical system. Long hours of high loads during times of day that folks are sleeping.

 

[Kzooman]

Thanks everyone for the quick responses, I did get an electrician out right away yesterday after seeing all your responses, and he found my 50AMP breaker had some rust on the terminal and had rattling components. I also had him replace the MAIN 100 Amp breaker, and it's terminal was heavily rusted. Apparently, the garden hose spigot had a leak before I bought the house, and this water was leaking right on top of the breaker panel. I borrowed an IR Thermal Imaging Camera to look for hot spots, and it's all nice and cold even at the full 32Amps setting on the UMC. Also, no more buzzing sound. Thank You for potentially saving my house from burning down. Here's a picture of the 2 breakers I had replaced.