EVITP Load Calculations and Service Capacity Assessment

Question 1

An EVSE draws a maximum of 40 A. Under NEC 625, what is the minimum overcurrent protective device rating for its branch circuit?

Accepted Answer

50 A

Answer

The NEC treats EV charging as a continuous load, so the overcurrent device must be at least 125% of the maximum load: 40 A × 1.25 = 50 A.

Question 2

A Level 2 charger runs at 240 V and 32 A. About how much power does it deliver?

Accepted Answer

7.7 kW

Answer

Power = voltage × current: 240 V × 32 A = 7,680 W, or about 7.7 kW.

Question 3

In a dwelling-unit load calculation under the 2023 NEC (220.57), what load must you use for EVSE?

Accepted Answer

7,200 W or the nameplate rating, whichever is larger

Answer

NEC 220.57 sets the EVSE load at 7,200 W (volt-amperes) or the equipment's nameplate rating, whichever is larger.

Question 4

A 60 A circuit supplies a hardwired EVSE with an adjustable current setting. What is the highest continuous charging current you can set?

Accepted Answer

48 A

Answer

A continuous load may not exceed 80% of the overcurrent device rating, which is the inverse of the 125% rule. 60 A × 0.8 = 48 A.

Question 5

You want to add EVSE to an existing commercial service. Which NEC method lets you size the added load from the facility's measured maximum demand?

Accepted Answer

NEC 220.87, using a year of maximum demand data or a 30-day recording at 15-minute intervals

Answer

NEC 220.87 lets you determine existing load from real maximum demand data: one year of utility data, or a 30-day recording at 15-minute intervals if utility data isn't available. You then add the new EVSE load.

(EVITP) Electric Vehicle Infrastructure Program Practice Test

(EVITP) Electric Vehicle Infrastructure Program Practice Test

EVITP Load Calculations and Service Capacity Assessment