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I'm planning on installing a load shedding EVSE (Wallbox Pulsar Plus 40A paired with their Power Meter for Energy Management Solutions). After a failed attempt to clamp the service line I plan on installing the CT clamps on parts of the load.

My service is 100A. My service panel is 125A. See pictures here. In the same panel I will have the following breakers/load:

breaker max load description
40A 32A SolarEdge SE7600H-US inverter with max continuous output current 32A
50A 40A (load shed) Wallbox Pulsar Plus 40A
30A 19A heat pump HVAC label
15A 4A air handler label
15A <1A Power Meter for Energy Management Solutions
15A (the only single pole) <12A driveway plugs, security cameras and lights
100A 100A subpanel

I'm planning on installing the CT clamps around the subpanel and EVSE wires making sure the same phase wires are clamped together.

The load shedding EVSE allows setting the max current its meter sees. What's a safe value when it only sees part of the load? Busbar rating minus max values of all the non clamped loads? Should I be subtracting the full solar? Does the solar 120% rule NEC 705.12(B)(3) point 4 matter here? Should I be subtracting the theoretical max of the 110V/15A circuit?

The safest value is probably: 125 (busbar) - 32 (solar) - 19 (HVAC) - 4 (air handler) - 1 (power meter) - 12 (110V/15A circuit) = 57A

Is this right? If I pigtail the HVAC and the 110V circuit to allow me to clamp those wires too, I could set the max current to 57 + 19 + 12 = 88A?

1 Answer 1

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The service size must be reduced by the Load Calculation for the wires you are not clamping.

That should result in a breaker ampacity, with max EV limit being 80% of that.

Do a Load Calculation on the whole house, then do another Load Calculation on the wires you are clamping. Subtract the two for the Load Calc on the wires you are not clamping. The house's "3 VA per square foot" is vague, and best to throw it into the "not clamping" side of the calculation.

Make sure to clamp the solar. It is an anti-load which increases your EV limit as it comes in.

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