UL 2231-1

Personnel Protection Systems for Electric Vehicle (EV) Supply Circuits: General Requirements

UL 2231-1

1 Scope

1.1 These requirements cover devices and systems intended for use in accordance with the National Electrical Code (NEC), ANSI/NFPA 70, Article 625, to reduce the risk of electric shock to the user from accessible parts, in grounded or isolated circuits for charging electric vehicles. These circuits are external to or on-board the vehicle.

1.2 The devices and systems covered by these requirements must be compatible with the designs of charging systems and vehicles where use is intended and shall be rated accordingly. To assure compatibility, the features contained in 1.3 – 1.5 are required of the charging system, the vehicle, or both.

1.3 The type of vehicle covered by these requirements, including all accessible conductive parts on the vehicle, have one or more of the following:

a) Provision for the connection of an equipment grounding conductor during battery charging, unless the vehicle has a system of reinforced or double insulation or all of the circuitry on the vehicle is electrically isolated from the supply circuit;

b) Provision for the connection of ground-monitoring conductors, where required;

c) Reinforced insulation or be double-insulated from the supply circuit; or

d) No direct connection between current carrying conductors and the vehicle chassis.

1.4 These requirements cover devices and systems where the grounding path impedance of the charging system to the vehicle is less than or equal to the impedance of the ungrounded conductor or conductors.

1.5 These requirements cover devices and systems where a continuous current less than 70 mA RMS is available from any accessible part of the charging system.

1.6 Devices covered by these requirements are intended to interrupt the electric circuit to the load when:

a) A fault current to ground exceeds some predetermined value that is less than that required to operate the overcurrent protective device of the supply circuit,

b) The grounding path becomes open-circuited or becomes an excessively high impedance, or

c) A path to ground is detected on an isolated (ungrounded) system.

1.7 These devices and systems are intended to be applied on electrical systems or include derived systems that are:

a) Either end-grounded or centrally grounded when the operating voltage is 150 Vrms or less,

b) Centrally grounded when the operating voltage is greater than 150 Vrms, or

c) Isolated (ungrounded).

1.8 Charging circuit interrupting devices covered by these requirements are investigated for their ability to provide protection based on:

a) The type of current (60 Hz AC, DC, a combination of AC and DC, or AC at frequencies greater than 60 Hz) present in the circuit to be protected, and

b) Voltage.

1.9 These requirements do not cover ground-fault circuit-interrupters (GFCIs) intended for use as personnel protection in accordance with the National Electrical Code on grounded 120 Vrms to ground, 60 Hz circuits. Such devices are covered under the Standard for Ground-Fault Circuit-Interrupters, UL 943.

1.10 This standard includes the Scope, Glossary, and Description of Requirements, including the required features of protection systems. The Standard for Personnel Protection Systems for Electric Vehicle (EV) Supply Circuits: Particular Requirements for Protection Devices for Use in Charging Systems, UL 2231-2, contains the Performance and Construction requirements for protective devices that would become a part of a charging system.