AC Level 2 EV Charger electrical wiring
Canada/USA residential voltage is 120-240 volts
Commercial/industrial buildings voltage is usually 120-208 volts

(Consult local electrical codes for actual requirements)

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Table 1
Circuit Breaker (240V double-pole)
Residential appliances
Wire size, copper, AWG
EV Charger (continuous output)
Power @ 208 volts
Power @ 240 volts
60 amps

4
48 amps
10 kilowatts
11.5 kilowatts
50 amps
Electric Range
6 see ampacity table
40 amps
8.3 kilowatts
9.6 kilowatts
40 amps (see this graphics)
Electric Range
8 see ampacity table
32 amps
6.6 kilowatts
7.7 kilowatts
30 amps (see this graphics)
Electric Dryer
10
24 amps
5.0 kilowatts
5.7 kilowatts
20 amps

12
16 amps
3.3 kilowatts
3.8 kilowatts

Continuous load such as EV charging should only draw 80% of the circuit breaker's rating to avoid overheating and tripping.
See https://www.ecmweb.com/basics/sizing-circuit-breaker

You can buy Level 2  "EV chargers" (technically speaking, these are EVSE Electrical Vehicle Supply Equipment) from manufacturers such as  https://www.clippercreek.com/    https://www.autochargers.ca/   , car dealers, BestBuy, Amazon, Walmart, Costco etc. EVSE act like an expensive interface/safety device to protect (1) the wiring (overloads, overheat, fire), (2) personnel (electric shock, electric burns) and (3) vehicle on-board circuits (communications). The actual charging circuit is inside the vehicle called On-Board Charging Module (OBCM).

An important parameter (4th column in Table 2) is the vehicle's AC charging "Acceptance Rate" (kilowatts) which sets the upper limit of charging. J1772 AC Level 2 charging allows up to 19.2 kilowatts of power delivery (240 volts @ 80 amps).
DC charging (Level 1 DC and Level 2 DC) has much higher power ratings but it is not the subject of this article.

Many Level 2 chargers sold at big-box stores are 32 amps (7.7 kW @ 240 volts or 6.6 kW @ 208 volts).
Typical public charging stations at libraries, city halls, shopping malls, etc are 6.6 kilowatts or 6.0 kilowatts

(2019) If you have a 32 amps EVSE at home (7.7 kW @ 240 volts), one hour of charging time at home will give these approximate range:
Tesla Model 3 SR+ (7.7 kWh): 51 km. Nissan Leaf (6.6 kWh): 35 km. Chrysler Pacifica PHEV (6.6 kWh): 21 km.
Hyundai Sonata PHEV 9.8 kWh battery (3.3 kWh in 1 hour) 15 km [due to 3.3 kW acceptance rate].

(2019) If you opt for a 40 amps EVSE at home (9.6 kW @ 240 volts), one hour of charging time at home will give these approximate range:
Tesla Model 3 SR+ (9.6 kWh): 64 km.
Nissan Leaf, Chrysler Pacifica PHEV ranges are the same as a 32 amps charger because the respective vehicle's Acceptance Rates are already maxed out.

(2019) Opting for a 40 amps EVSE at home for Nissan Leaf, Chrysler Pacifica, etc. does not speed up charging except it provides a potential for future vehicles with higher AC charging Acceptance Rates.

The many different electrical plugs used by 240 volts EV chargers are very confusing. EVSE manufacturers seem to converge on the NEMA type 14-50 plug and NEMA 14-50R receptacles (up to 50 amps). Or, you can choose a "hardwired" version when you buy your EVSE.

Table 2


Q&A Notes:
If I have a 30A circuit and a 24A EV charger, can I plug in a Chrysler Pacifica PHEV? Yes, the charging current is set at 24A.

If I have a 40A circuit and a 32A EV charger, can I plug in a Chrysler Pacifica PHEV? Yes, the Chrysler Pacifica can accept 27.5A.

If I have a 30A circuit and a 32A EV charger, can I plug in a Hyundai Sonata PHEV? Yes, Sonata will charge at 14A. But there is a problem with this installation: if someone plugs in a Tesla Model 3, the EV Charger will deliver 32A to the Tesla. In this scenario, the 30A circuit breaker will trip within seconds (or minutes) because an overload condition occurs (drawing 32 amps on a 30 amp circuit).
Solutions to above problem: (1) Replace the 32A charger by a 16A or 24A charger or (2) Keep the 32A EV charger but upgrade the wiring from 30A to 40A: Use a 40A circuit breaker and replace the #10AWG wires by #8AWG wires.

© 2019 Nicholas Fong

nicholas.fong@gmail.com

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Last updated: 2019-11-16

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