EVT High Voltage Electrical Systems & Wiring

Question 1

What is the standard color code for high-voltage wiring in electric vehicles according to SAE and FMVSS 305 standards?

Accepted Answer

Orange

Answer

SAE and FMVSS 305 standards require high-voltage wiring in electric vehicles to use an orange outer jacket to identify HV cables and warn technicians.

Question 2

At what minimum DC voltage level are electric vehicle systems generally classified as 'high voltage' under FMVSS 305?

Accepted Answer

60V DC

Answer

FMVSS 305 and international safety standards classify any voltage above 60V DC (or 30V AC) as high voltage requiring special precautions.

Question 3

What is the primary purpose of the manual service disconnect (MSD) in an EV high-voltage system?

Accepted Answer

To physically interrupt the HV circuit for safe servicing

Answer

The MSD physically breaks the HV circuit, de-energizing the system and allowing technicians to safely service HV components.

Question 4

What is the purpose of the precharge circuit in a high-voltage EV system?

Accepted Answer

To slowly charge large capacitors before main contactors close, limiting inrush current

Answer

The precharge circuit limits inrush current by slowly charging inverter and DC/DC capacitors through a resistor before the main contactors close, preventing arcing and component damage.

Question 5

What minimum rubber insulating glove class is required when working on EV high-voltage systems operating up to 1000V?

Accepted Answer

Class 0 (1000V rated)

Answer

Class 0 rubber insulating gloves are rated for use on systems up to 1000V, making them the minimum class required for most EV high-voltage work.

(EVT) Certified Electric Vehicle Technician Practice Test

(EVT) Certified Electric Vehicle Technician Practice Test

EVT High Voltage Electrical Systems & Wiring