That helps. I kept trying to Google that info with poor results.. I have a Tesla that'll take up to 48A for level 2 charging. 250KW for level 3. 40 is max only for continous loads on a 50A which is defined by more then 3 hours. Even though I follow that for EV charging regardless. For me it makes sense to ger a plug in 40A so when I roadtrip in my Tesla I can charge faster at rv parks.
You may be confusing the National Electric Code NEC, and the Underwriter Laboratories UL.
‘The NEC is what all electricians and manufacturers go by.
UL does not rate or rule on loading, they rate an appliance as meeting their standards.
From the NEC code,
If you have a branch circuit supplying nothing but continuous loads, (not motors), then the minimum conductor size must have an ampacity of 125% of the load by 210.19(A)(1) and the overcurrent protection must be 125% of the load by 210.20(A). Therefore
, the breaker must be loaded to no more than 80% of its rating. These were not changed in the 2002 code.
The UL code agrees with the NEC,
From the 2003 UL white book
CIRCUIT BREAKERS, MOLDED-CASE AND CIRCUIT BREAKER ENCLOSURES (DIVQ)
MAXIMUM LOAD
Unless otherwise marked, circuit breakers should not be loaded to exceed 80 percent of their current rating, where in normal operation the load will continue for 3 hours or more.
in practical terms, of real world experience, If you load ONE leg of a 50 amp breaker with 45 amps for 30 to 60 minutes you will trip the breaker. If you load both legs with 45 amps, it will trip the breaker in 30 minutes or less. And if, as you say, you load it with 48 amps on both legs, you will be going out to the breaker box every five minutes and after the second or third time, you will be buying a new breaker. I only say this as a retired Registered Electrical Engineer with 42 years of experience.
The major problem you risk by exceeding 80% of the rated capacity of a circuit is a fire.