ChargePoint Express 250 - Grounding and Earthing Requirements

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de-energized. The isolation monitor operates continuously during charging to ensure the output is
always galvanically isolated. UL 2231-1 requires that an isolation monitor interrupter (IMI) is provided
in the product and evaluated during operation as part of certification testing.
Although RCD/GFCI use is required in mode 1,2,3 AC charger installations, neither UL nor IEC
mandate an RCD for a permanently installed mode 4 isolated output DC charger.
RCD Settings
For Standalone Express 250 installations where the use of an RCD (RCCB or RCBO) cannot be
avoided, use the following settings to minimize nuisance trips:
• Type: A, F or B (type B and F preferred)
• Trip threshold: 500 mA
• Trip delay: 150 ms
If an RCD must be employed for a Paired installation, contact ChargePoint.
Region Specific Notes: UK
When discussing DC charging station installations with a UK DNO (utility), include these two
considerations:
• Where possible, request TN-S earthing from the DNO (distribution network operator)
• The Express 250 represents a Class I construction, balanced 3-phase load greater than 500 W
Either statement allows UK DNOs to provide a PME earth terminal and avoids the requirement for a
TT earthing arrangement and associated (300 mA) RCD. The second statement meets the clause in
the IET Code of Practice for EV Charging Equipment Installation, 3rd Edition that allows the DNO to
provide a PME connection for “on the street equipment”.
Installations at petrol stations are a special case that requires additional site planning. Contact
ChargePoint for more information.
Grounding/Earthing Requirements
• The Express 250 must be connected to a grounded, metal, permanent wiring system.
• North America: A grounded service neutral conductor must be run with circuit conductors
and connected to an equipment-grounding terminal on the Express 250.
• Europe: Use TN-S or TN-C-S configurations. (TT is not recommended because it requires
RCDs.)
• Ensure a grounding conductor that complies with local codes is properly grounded to earth at
the service equipment or, when supplied by a separate system, at the supply transformer.