Energy Management System on Sub

[TwistLock]

Any violation installing an add on Energy Management System onto a ‘sub’ panel ?
EMS would feed EVSE. Any preferred EMS brands / devices ? (BlackBox etc).

EVSE requested at a townhouse. 70 amp (siemens) interior ‘sub’ is only source available. Meter mains are on other side of building (zinsco).
Sub fed with #2 AL cable. 40a HVAC / 40a Steam existing, rest are 15 / 20 amp branch.
MercBenz Wallbox by EVbox

 

[jaggedben]

Perhaps depending on your code cycle, I believe using an EMS to avoid sizing to a full load calc is still of dubious legality. Even though it makes sense and is apparently fairly widely accepted. That may change in the 2026 NEC to where it is expressly permitted.

That said, I see no difference between a service or a subpanel feeder.

 

[Sierrasparky]

It shouldn't be a issue especially in CA. I use them in condo's where I mostly use the box that intercepts the unit's feeder and creates a new branch circuit. The controls limit the total load of 80% of the main breaker size. Sort of a no brainer. Just need space to spice or Feed/refeed.

 

[TwistLock]

Thanks guys. Client contacted me because first electrician said he couldn’t do it, so that made me curious. I’ve read art.750, & 220.70 etc. and don’t see a problem either (other than design/failure of the EMS).