davewill
Active Member
The wrong part is that the car and EVSE will handle things if the circuit is too big. You gave no other rationale for saying that 90a would be OK until you were called out.
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
QUESTION: How big of a Charging circuit can I get installed?
- Thread starter Jlindo
- Start date
Let me fix that for you to make it more clear:
The wrong part is that you made the assertion that the car and EVSE will handle things if you blindly install a circuit that is too big for the main panel and utility service. In fact, they will not. You gave no rationale for the assertion that 90 amps would be OK until you were called out.
The incoming service cable is 1/0 aluminum, which is most likely owned by the Utility, not the homeowner. True that they do not need to follow NEC ampacity requirements, but that cable still needs to be accounted for in the project. Best advice is to find out what your peak demand is and determine from that value, what the remaining capacity of the service is. NEC 220.87 dictates duration for the measurements. If the Utility can get this information from the smart meter, that is perfect! Hopefully the electric heat has been off for a while so that the peak demand value represents the load recorded with the electric heat gone.
Also, there is a tap at the SE conductors, so there are more loads -- possibly a second small panel somewhere on the property not included in the 200 Amp service panel. All the more reason to get an answer on what the peak demand is before proceeding with any work.
Also, there is a tap at the SE conductors, so there are more loads -- possibly a second small panel somewhere on the property not included in the 200 Amp service panel. All the more reason to get an answer on what the peak demand is before proceeding with any work.
rhumbliner
Member
Lotta good advice here but I’ll add one more suggestion. When faced with the same situation I swapped out my electric oven, water heater, and dryer for natural gas models. That freed up plenty of capacity for a 100-amp breaker for my HPWC. And my wife loved getting new appliances.
Of course, this assumes your house is plumbed for gas, as mine was.
You're looking at the ampacity tables for in-building wire. The tables are different for the power company side of the meter. They (are allowed to) push things a lot harder. I've seen a house with 100A service (24kva) run on a dedicated 10kva transformer, and multiple houses wired on a 25kva transformer. My 100A service is fed with overhead 4 gauge AL (which is only good for 75A per the tables).
Stuff out in open air is assumed to be better cooled than in-wall wiring, etc.
brucet999
Active Member
To be precise, what is clear is that your panel is rated for 200A, but that has nothing to do with the ampacity of the PoCo supply wires. You need to check with them to find out what amperage they can deliver to your house. Of course, it is highly unlikely that you would ever draw 200 amps of power at any one time.
Similar threads
