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Tga was saying that he didn’t believe there was a residential breaker temperature rated for 90 degrees C. Not 90 amps.
Lasttoy
Active Member
You can only charge at 80amps if you have dual chargers in car. That requires 100amp breaker that can only be installed in a house with 200 amp main. I bought car with 2 inverters, but can use second one at home, only gave 100 amp main. I have 14.50 with 50 amp breair.
FlatSix911
Porsche 918 Hybrid
That's interesting that 80 amp is listed as 54, but half that amperage is listed at 29. I wonder if there are heat losses somewhere in there.Here is the Tesla guide on the HPWC installation ... Home charging installation
View attachment 268526
BrokerDon
Active Member
Our "inventory" 2015 P85D came with dual 40A chargers so we CAN charge at 80A... but only do if we need to recharge in a hurry since it heats up the HPWC, HPWC cable and Tesla charge port quite a bit. Heat isn't good for electronics + indicates power lost during charging so we normally charge at 50A (~ 32 MPH charge rate). This will recharge our completely empty 85kWh (~226 miles at 90%) battery in ~ 4.5 hours... plenty of time during our utility company's cheapest kWh rate Super Off-Peak 10:00 PM to 8:00 AM).
IMHO 50A circuit / 40A HPWC charge rate should be fine for most Teslas... and save $$$ in upgrading onboard Tesla chargers + electrical infrastructure costs.
IMHO 50A circuit / 40A HPWC charge rate should be fine for most Teslas... and save $$$ in upgrading onboard Tesla chargers + electrical infrastructure costs.
FlatSix911
Porsche 918 Hybrid
Tesla is only listing the maximum charge rates for the current generation of cars.
The classic Model S is listed at the bottom of the page with a link to the correct maximum charge rate of 80A with 58 miles of range per hour.
KArnold
Active Member
On a related question I'm having some remodeling done. Maybe not the best way but currently I have a 14-50 on a 30-amp circuit - in my 100d capable of 72 amp charging I have manually rolled that down to 24 amps. Not terribly fast but it works most of the time.
Was thinking with the upgrade to just have the electrician make this a 60-amp still with the 14-50.
My question - at 60 amps (48 usable) (or even 30 amps) is there any advantage to having a HPWC? Short of an emergency trip I can't imagine ever needing the time I might gain with a 90-amp circuit. No plans for a 2nd EV.
Thanks in advance.
Was thinking with the upgrade to just have the electrician make this a 60-amp still with the 14-50.
My question - at 60 amps (48 usable) (or even 30 amps) is there any advantage to having a HPWC? Short of an emergency trip I can't imagine ever needing the time I might gain with a 90-amp circuit. No plans for a 2nd EV.
Thanks in advance.
Lasttoy
Active Member
A 14.50, 50 amp breaker in garage is all you really need. It will always be full every morning. If you have dual chargers and 200 amp service, you can install a 100amp breaker, 00 gauge wire, for faster charge. But the install cost are very high.
Lasttoy
Active Member
Someone is passing out wrong info on home charging. Tesla has a number to call just to help us. I called them ,my electrician called to make sure I heard it right. 100 amp service equals 50 amp breaker, 06 wire single charger. Dual chargers need 200 amp service to house, empty slot for 100 amp breaker, 00 wire. My house only has 100 amp service, so my second charger is never in play at home.
If in doubt, call tesla home charger team.
If in doubt, call tesla home charger team.
You shouldn't really do this - better and safer to install a 14-30 outlet and get the matching UMC adapter. That will automatically force the car to 24A - no need to manually dial back the charge current.
There have been examples of cars forgetting the reduced setting (GPS problems, software updates resetting settings, etc) and overloading the circuit. If you have a defective circuit breaker that doesn't trip properly on overload, this could cause a fire.
You can't install a 14-50 with a 60A breaker - it's a major NEC violation, fire hazard, a general no-no, and won't pass inspection. No (competent, licensed) electrician would do this. Anyone who does this (and calls themselves an electrician) probably found his licence at the bottom of a Cracker Jack box.
The only way to charge at 48A is with a HPWC. The UMC can't deliver more than 40A (and the new ones are limited further to 32A). At UMC power levels (<=40A), the HPWC is arguably heavier duty, less likely to overheat, and a bit more robust (being hardwired vs a plug).
If you are upgrading the circuit anyway, I'd probably go to the full 90A - since you're paying the labor anyway, the only real cost difference is the heavier wire.
Yes, sorry for the confusion - 90A breakers exist. But I don't think you'll find a residential, low voltage (<600V) breaker with a 90 degree C rating. I've only seen ones marked 60/75 or 75. That means you can't use the 90 degree column for rating conductors to attach to it.
See Ampacity Charts for ampacity ratings vs temp
I looked up the Square D QO line (that's what I have) - they're all 60/75 or 75 - http://static.schneider-electric.us/docs/Circuit Protection/Miniature Circuit Breakers/QO-QOB Circuit Breakers/0730CT9801R108.pdf
If the lugs on my breaker are 90 degree C rated, can I use 90 degree C wire at its rated ampacity?
Probably more than you ever wanted to know about temp ratings: http://www2.schneider-electric.com/resources/sites/SCHNEIDER_ELECTRIC/content/live/FAQS/175000/FA175147/en_US/Wire Terminations 0110DB9901R2-02.pdf
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00 (aka 2/0 or "double aught") is never needed for a HPWC install. 2/0 copper is good for 175A max (charging at 80% would be 175*.8 = 140A charging) - that's double what a 100D @ 72A needs.
The only mention of wire size in the HPWC installation manual (see here) is on page 18:
3 ga is good for 100A intermittent, 80A continuous at 75°C. Many people have used 2 ga, as 3 ga can be hard to find. 2 ga is good to 115A/92A @ 75°C, but can be hard to install (it's almost too big to fit in the terminals).
2 ga is 0.25" in diameter. 2/0 is 0.36" in diameter. You could not use 2/0; it is definitely too big to fit in the HPWC terminals.
FlatSix911
Porsche 918 Hybrid
Here are the installation guides for the standard NEMA outlets along with the recommended circuit breaker & wire size 
https://www.tesla.com/sites/default.../NEMA_14-50_installation_guide_NA_US_2017.pdf
https://www.tesla.com/sites/default.../NEMA_14-30_installation_guide_NA_US_2017.pdf
https://www.tesla.com/sites/default.../NEMA_14-50_installation_guide_NA_US_2017.pdf
https://www.tesla.com/sites/default.../NEMA_14-30_installation_guide_NA_US_2017.pdf
Fun fact, this is from the Tesla website even you as the dual charger option after the fact:
"Model S vehicles with a single charger configuration can charge at a maximum of 29 miles of range per hour of charge. By upgrading to add the 2nd on-board charger, your Model S will be able to get up to 58 miles of range per hour of charge when charging with the Wall Connector. The dual chargers allow twice the conversion capacity as the single charger when the power is available."
"Model S vehicles with a single charger configuration can charge at a maximum of 29 miles of range per hour of charge. By upgrading to add the 2nd on-board charger, your Model S will be able to get up to 58 miles of range per hour of charge when charging with the Wall Connector. The dual chargers allow twice the conversion capacity as the single charger when the power is available."
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