EV Load Management
Emporia: EV Load Management Charger Size
The Emporia EV Charger with PowerSmart load management is a throttle (current-modulating) device. This is the charger it enables and the branch it needs, with the NEC basis declared by us and the manufacturer named only for how the device behaves.
How the Device Works
The device function: PowerSmart automatically raises or lowers the Emporia Pro's charge rate based on what else is running in the home, keeping total draw within the panel's safe capacity. Emporia PowerSmart is a current-modulating device: the EVSE hardware is a full 48A (hardwired) or 40A (plug-in) unit, and the software reduces the DELIVERED charge current to keep the whole-home draw under the service rating. The branch is wired for the full hardware output; the throttling only limits delivered current, never the conductor sizing.
Adjustable range / setpoint: adjustable 6-48A; setpoint = the Service Rating (main-breaker amps) via Vue CTs.
Hardware Models & Branch
| Hardware output | EVSE output | Branch conductor | Branch breaker | Ground |
|---|---|---|---|---|
| 40A | 40A | #8 Cu | 50A | #10 Cu |
| 48A | 48A | #6 Cu | 60A | #10 Cu |
The branch is always 125% of the full EVSE hardware output (NEC 210.20(A) / 625.41). An external device never shrinks the branch; the only legitimate reduction is the EVSE's own restricted-access adjustable rating (NEC 625.42(B)).
Listing & Source
Listing: UL 817, UL 991, UL 2251, UL 2594
Device function transcribed from the manufacturer: Emporia documentation, accessed 2026-07-11. TYPE = throttle: PowerSmart dynamically ADJUSTS the charge rate; it does not disconnect. Setpoint is the Service Rating, measured with Vue CTs. A 'Guaranteed Charge Rate' (the NEC Art. 220 headroom) stays available if PowerSmart drops.
Frequently Asked Questions
How big an EV charger does the Emporia allow?
The Emporia is a throttle device: the EVSE hardware is a full 40A or 48A unit, and it modulates the DELIVERED current to keep total demand under the service rating. The hardware size does not change; what changes is the delivered current, capped to your service headroom. Enter your service and demand in the calculator to see the delivered current.
Does the Emporia let me use smaller wire?
No. The branch conductor and breaker are always sized to 125% of the full EVSE hardware output (NEC 210.20(A) / 625.41), never the throttle setpoint. An external throttle does not change the charger's rating; if it fails or is bypassed the EVSE can pull its full current. The only legitimate branch reduction is the EVSE's own restricted-access adjustable rating under NEC 625.42(B).
What NEC sections cover the Emporia?
The load-management basis is our own derivation: NEC 220.70 permits an EMS-controlled maximum in the service or feeder load calculation, 625.42(A) relaxes the service and feeder for a listed EMS in accordance with 750.30, and 750.30 requires the EMS to keep load within conductor ampacity. The branch stays at 125% of the charger output (210.20(A) / 625.41). Emporia states the device function; the NEC basis is declared here, not attributed to the manufacturer.
Compute Your Biggest Charger
Enter your service and measured demand for the base NEC 220.87 answer, then compare it against what a throttle device unlocks.
Other Load-Management Devices
DCC (Thermolec / RC Devices / RVE)
shed (disconnect). EV charging-station pass-through breaker rating.
Wallbox
throttle (current-modulating). EVSE hardware output (48A / 40A models).
Splitvolt
circuit-share. existing shared-branch (dryer) breaker rating.
With vs Without Load Management
The same service, both ways: the biggest charger with and without a device.
Related Tools
EV Load Management Hub
The inverse 220.87 solve and all three device types.
Load Calculator (NEC 220)
The forward direction: 220.82 sizing and the 220.87 existing-load check.
EV Charger Calculator
Wire, breaker, and panel capacity for a Level 2 charger per NEC Article 625.
Wire Size Calculator
The correct conductor per NEC 310.16 with the 110.14(C) terminal cap.