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Equipment sizing for an 80A Tesla Car Charger

Question asked by dcoon on Jan 29, 2018
Latest reply on Jan 31, 2018 by chiefns830

I am reviewing the installation of Tesla 80A charger in a residence that has only 40 amps left on the main panel after the load calcs.  The electrician states it is his intention to set the charger dial (dip switches) at 30 amps, not to exceed the main panel rating.  Looking at 625.41 in the 2017 NEC, I read that the OCPD and the conductors are to be sized at 125% of the max rating. So 80 amps x 1.25 =100 amp for these components, even though the charger will be set for 30 amps.

In the next section 625.42 the code appears to make concession for the turned down output of the charger in the sections references to "automatic load management".  I cannot find this defined in the book.  In the Handbook, in the narrative below this section is the statement "Connection of EV supply equipment to "Automatic Load Management Systems" can preclude the need for a service or feeder upgrade at an existing electrical installation.  Is the use of "DIP" switches in the tesla wall charger panel and its communication with the on board charging systems in the car to moderate the current drawn, the definition of the automatic load management system? 

So in short, I am sizing the OCPD and conductors to the panel for the max (80 x 1.25%) and as long as no one turns up the knob in the Tesla charger, the panel is safe.  Or is this stating that all the supply circuits and protection are allowed to be designed around 30A charge rate?

Thanks 

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