EV Lesson 4

Conductor insulation does not have an effect on voltage drop. Select one: True False

True

When calculating the voltage drop on a conductor of a given length, the following values must be considered: conductor material, conductor length, and conductor operating temperature. Select one: True False

True

A Level II EVSE with a rating of 32 amperes at 208 volts is installed. What is the minimum size copper equipment grounding conductor required to serve the installation? Select one: a.10 AWG b.8 AWG c.6 AWG d.4 AWG

a.10 AWG 250.122 - the EVSE will be served by a 40A OCPD; therefore, the minimum size equipment ground will be 10 AWG.

Two Level II EVSE circuits are installed in the same PVC conduit. Each EVSE is served by a 40-ampere circuit at 240 volts with an EGC run along with the circuits. What size copper EGC is required for this installation? Select one: a.10 AWG b.8 AWG c.6 AWG d.4 AWG

a.10 AWG Note: T250.122 - 40A Circuit = 10 AWG CU equipment ground

An office building has 22 kilovolt-amperes of lighting that is at continuous operation. It also has 35 20-ampere, 120-volt duplex receptacles. Both loads are fed from a 300-ampere panelboard operating at 120/240 volts, single phase. How much more continuous load can be added to the service? Select one: a.30,560 VA b.33,800 VA c.38,200 VA d.72,000 VA

a.30,560 VA (22 kVA × 1.25) + (35 × 180 VA) = 33,800 VA 300 A × 240 V = 72,000 VA 72,000 - 33,800 VA = 38,200 VA 38,200 VA × 0.8 = 30,560 VA is the capacity left on the continuous load

An existing 400-ampere, 120/208-volt, 3-phase, 4-wire service has 30 kilovolt-amperes of non-continuous load and 58 kilovolt-amperes of continuous load. How much more continuous load can be added to the service? (Note: Use 1.732 for the square root of 3.) Select one: a.33,281.92 VA b.41,436 VA c.102.5 kVA d.143.93 kVA

a.33,281.92 VA 30 kVA + (58 kVA × 1.25) = 102.5 kVA 400 A × 208 V × 1.732 = 144,102.4 VA Remaining VA available prior to continuous load correction = 41,602.4 VA 41,602 VA × 0.8 = 33,281.92 VA

Calculate the following correct copper conductor size so that the branch circuit has a maximum voltage drop of 2%. The load on the circuit is 32 amperes, the distance from the load to the panelboard is 400 feet, and the circuit is 208 volts, single-phase. a.3 AWG b.1 AWG c.1/0 AWG d.250 kcmil

b.1 AWG 2% × 208 V = 4.16 V 2 KIL / VD = A 2 × 12.9 × 32 A × 400' / 4.16 V = 79,384.6 cmil = 1 AWG

Nine Level II EVSEs are installed on a 3-phase, 4-wire 120/208-volt system. Each EVSE is 208/240 volts, single-phase and rated at 24 amperes. What is the minimum ampacity of the copper feeder conductors required to serve the installation? a.90 A b.156 A c.167 A d.180 A

b.156 A -24 A × 1.25 = 30 A required for each EVSE3 -units on each phase = 30 A × 3 = 90 A -Line current needed to find feeder size: 90 A × 1.732 = 156 A per line needed -156 A = 2/0 Copper

What is the general lighting load of a store with an area of 12,000 square feet? a.12,000 VA b.36,000 VA c.45,000 VA d.48,000 VA

b.36,000 VA 12,000 ft2× 3 VA per ft2 = 36,000 VA per Table 220.12 Continuous factors are not needed as actual lighting load is all that is requested. Correction factors will apply when sizing the branch circuit OCPD and conductors, which is beyond the question scope.

Three single-phase Level II EVSE are distributed equally on a 3-phase, 4-wire system and each EVSE draws 24 amperes. What is the line current on each phase? (Note: Use 1.732 for the square root of 3.) Select one: a.24 A b.41.56 A c.52.6 A d.64.33 A

b.41.56 A 24 A × 1.732 = 41.56 A per phase

What is the maximum voltage drop recommended for branch circuits and feeders/electrical systems in the National Electrical Code (NEC)? Select one: a.1% branch / 2% feeder/system b.2% branch / 4% feeder/system c.3% branch / 5% feeder/system d.It is recommended that no voltage drop be allowed in the system.

c.3% branch / 5% feeder/system

What is the minimum copper THHN feeder size for 12 EVSEs rated at 24 amperes on a 3-phase, 4-wire, 120/208-volt system, assuming four EVSE per phase? (Note: Use 1.732 for the square root of 3.) Select one: a.250 kcmil b.350 kcmil c.4/0 AWG d.2/0 AWG

c.4/0 AWG 24 A × 1.25 = 30 A There will be four per phase. 30 A × 4 = 120 A per phase Line current is 120 A × 1.732 = 208 A feeder = 4/0 Copper

What is the minimum branch circuit size for a Level II EVSE with a 32-ampere current rating? Select one: a.32 A b.35 A c.40 A d.55 A

c.40 A 32 A × 1.25 = 40 A minimum OCPD

Additional EVSEs are to be added to an existing 120/208-volt, 3-phase, 4-wire, 600-ampere service with 220 amperes of non-continuous load and 172 amperes of continuous load. The EVSEs each draw 32 amperes. How many new EVSEs can be added to the service? (Note: Use 1.732 for the square root of 3.) Select one: a.2 b.3 c.6 d.9

c.6 220 A + (172 A × 1.25) = 435 A 600 A - 435 A = 165 A 165 A × 0.8 = 132 A left (due to EVSEs being continuous loads) (32 × 1.732) = 55.43 132 A / 55.43 = 2.38 or 2 per phase Total = 6 EVSEs

What is the minimum size XHHW-2 copper conductor permitted to supply a Level II EVSE that has a 30-ampere current rating, assuming 75° terminations? Select one: a.12 AWG b.10 AWG c.8 AWG d.6 AWG

c.8 AWG 30 A × 1.25 = 37.5 A = 8 AWG

Calculate the voltage drop on a single-phase circuit with 32 amperes of load, a distance of 320 feet from the load to the panelboard, and served by 8 AWG copper THHN conductors. Select one: a.13 V b.14 V c.15 V d.16 V

d.16 V 2KIL / A = VD(2) × 12.9 × 32A × 320' / 16,510 cmil = 16 V

A 32,000 square foot office building has 120 20-ampere, 120-volt duplex receptacle outlets. What is the branch circuit receptacle load? Select one: a.9,600 VA b.21,600 VA c.28,000 VA d.32,000 VA

d.32,000 VA 220.14(K) - use largest of either 1 VA per square foot or 180 VA per outlet. 180 VA × 120 = 21,600 VA 32,000 ft2 × 1 VA = 32,000 VA