phidauex
Well-Known Member
- First Name
- Sam
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- Dec 8, 2020
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- Colorado
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- 2021 MachE 4EX, 2006 Prius, 1997 Tacoma
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- Renewable Energy Engineer
Yes, the 2020 NEC allows for load sharing chargers. They call it an "automatic load management system".Out of curiosity how do you wire up multiple units for power sharing? Do you have two Nema 14-50R outlets, etc. wired off the same breaker? If so, is that really allowed by code (NEC)? I would think that would be frowned upon as typical 240V home appliances aren't designed to power share, even though functionally I know it would work and be safe (assuming the wiring is correct for the breaker) as the EVSEs would be managing the combined max current.
I assume we will eventually be a two EV household and I do the like the idea of just letting two EVSEs share the power automatically between two vehicles rather than my wife and I having to negotiate/remember which days of the week we get to/need to plug-in one shared EVSE.
625.42 Rating
The power transfer equipment shall have sufficient rating to supply the load served. Electric vehicle charging loads shall be considered to be continuous loads for the purposes of this article. Service and feeder shall be sized in accordance with the product ratings. Where an automatic load management system is used, the maximum equipment load on a service and feeder shall be the maximum load permitted by the automatic load management system.
It doesn't seem obvious how the code treats the actual wiring of those - some inspectors might object to having two 14-50 receptacles on a single 50A breaker, but if they are used for EV chargers with a load management system then it appears to be legal. The problem is that if someone wanted to use them for two welders or two dryers then they would run afoul of the general requirements for receptacles - it would probably come down to the inspector's interpretation.
The case seems more clear for the hardwired case - it is OK.
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