Singapore wants 60,000 EV charging points by 2030. Every one of them needs to be tested and commissioned by a Licensed Electrical Worker. Here's what SS638 and SS555 require, what instruments you need, and why EV installations are a different challenge from standard LV work.
Singapore's Land Transport Authority has set one of the world's most ambitious EV charging infrastructure targets: 60,000 charging points by 2030, across public car parks, private developments, shopping malls, and industrial premises. As of end-2024, approximately 15,000 points were installed. The gap — 45,000 charging points in under six years — represents an enormous volume of electrical installation and commissioning work that will fall on Singapore's LEW community.
EV charging installation testing Singapore LTA requirements are more nuanced than standard LV electrical commissioning, because EV chargers introduce electrical characteristics that standard test procedures and instruments weren't originally designed for. DC fault current components, high-frequency switching transients, and GFCI (ground fault circuit interrupter) behaviour that differs from residential applications — all of these demand that LEWs and M&E contractors understand the specific requirements before they commission their first EV charging point.
This guide breaks down exactly what SS638 and SS555 require, what instruments do the job, and where contractors are most likely to get it wrong.
EV charging in Singapore sits at the intersection of multiple regulatory domains:
The standard an LEW must work to is SS555 — Singapore Standard: Code of Practice for Electric Vehicle Charging Systems — read alongside SS638. If there is a conflict, the more specific standard (SS555 for EV charging) takes precedence.
Key Stat
LTA data shows Singapore's EV population grew by over 300% between 2021 and 2024, reaching approximately 45,000 registered EVs. The charging infrastructure is already under pressure in certain HDB estates and mall carparks — and this is before the adoption curve steepens. EV charging installation work for contractors represents a substantial and growing revenue opportunity, but only for those who are compliant.
This is the technical point that many electricians trained on standard LV work miss until they encounter it in a commissioning test or, worse, an incident investigation.
Standard AC RCDs (Type AC) are designed to detect sinusoidal AC fault currents — the type of fault that occurs when a live wire contacts a grounded surface in a conventional power circuit. They work by monitoring the imbalance between line and neutral current through a toroidal transformer. A sinusoidal AC fault current saturates the toroid in a way the detector responds to.
EV chargers contain power electronic components — diodes, IGBTs, rectifiers — that can produce fault currents containing DC components. A DC fault current does not induce a useful signal in the RCD's toroidal core — it can saturate the core and actually prevent the RCD from tripping on a fault. A Type AC RCD on an EV charging circuit can therefore fail to trip during a genuine fault condition that would be lethal to a person in contact with the charger.
SS555 and IEC 61851-1 are clear: Type A RCDs (which detect both AC and pulsating DC fault currents) are the minimum for AC EV charging circuits. For DC rapid chargers, Type B RCDs (which detect smooth DC fault currents) are mandatory. And your RCD tester must be able to verify Type A and Type B RCD operation — a standard Type AC RCD tester does not verify the DC fault response. See our electrical testers for RCD testers capable of Type A and Type B testing.
All cabling from the DB board to the EV charger must be insulation-tested before energising. Use 500V DC for standard LV cables. The minimum acceptable IR value under SS638 is 1 MΩ, but for new cables the expectation is much higher — values below 50 MΩ on a new installation suggest a wiring fault. EV charging cables run in carparks are subject to mechanical damage from vehicles, so thorough IR testing before energising is especially important. See our insulation tester range for suitable instruments.
The EV charger housing must be solidly bonded to the main earthing system. Any failure in the protective bonding between the charger and earth means the charger casing can become live in a fault condition — and someone plugging in their vehicle's cable is in direct contact with that casing. Use a low-resistance ohmmeter to test continuity of the CPC from the EV charger back to the MET. SS638 requires the CPC resistance to be low enough to ensure the protective device will operate within the disconnection time for the circuit fault loop impedance.
Measure Zs at the EV charger terminals. The measured Zs must be low enough to guarantee operation of the backup protective device (MCB or fuse) within the required disconnection time. Table 41 of SS638 gives the maximum permitted Zs values for common protective device ratings.
This is the critical distinction. Test the RCD at the rated residual current (e.g., 30mA for a personal protection RCD) and verify that it trips within the required time (300ms maximum at rated current; 40ms at 5× rated current for standard RCDs). For Type A RCDs, your tester should verify both the AC and the pulsating DC fault response. For Type B RCDs on DC rapid chargers, a Type B-capable tester is required. Standard RCD testers provided with basic test kits typically only test Type AC — verify your tester's capability before the commissioning test.
Pro Tip
Keep a copy of the charger manufacturer's installation manual on-site during commissioning. EV charger manufacturers often specify maximum cable lengths, minimum earthing conductor sizes, and specific RCD types that differ from the generic SS555 minimum requirements. If the manufacturer's specification is more stringent than SS555, follow the manufacturer — and document that you did.
A growing proportion of Singapore's EV charging rollout is in outdoor carparks — HDB multi-storey carparks, private development surface carparks, and park-and-ride facilities. Outdoor charging points face a harsher environment than indoor installations:
For insulation resistance testing of outdoor EV charging circuits, the ambient humidity at the time of test matters. IR readings taken during or immediately after heavy rain on an outdoor circuit will be lower than the same circuit tested on a dry day — not because the insulation has degraded, but because surface moisture is providing a leakage path. Allow circuits to dry before concluding that an IR reading represents actual insulation quality.
Watch Out
Outdoor carpark EV charger installations in Singapore are frequently close to vehicle wash-down areas and subject to pressure washing. Verify that all weatherproof enclosures, conduit seals, and cable gland entries are correctly sealed before energising. A pressure wash after commissioning can drive water into an inadequately sealed enclosure and cause insulation failures that were not present during your commissioning tests.
Based on the SS555 and SS638 requirements above, an LEW commissioning EV charging points in Singapore needs:
All of these instruments need current SAC-SINGLAS calibration certificates, particularly if you are commissioning for a developer, property manager, or fleet operator who will be managing the chargers under a maintenance contract. Our calibration laboratory handles multifunction installation testers and insulation testers with fast turnaround. Contact Unitest to discuss calibration for your EV commissioning kit.
Singapore's EV charging rollout is creating a substantial new segment of electrical commissioning work. EV charging installation testing Singapore LTA requirements under SS555 and SS638 are specific: correct RCD type, insulation resistance, earth continuity, and earth loop impedance — all tested with appropriate instruments and all documented in a format that an EMA-compliant LEW sign-off can stand behind.
Unitest Instruments stocks the full range of instruments needed for EV charging commissioning — insulation testers, multifunction installation testers, and calibrated clamp meters. Our SAC-SINGLAS calibration lab keeps your instruments compliant. Browse our range or contact our technical team for guidance on building your EV commissioning kit.
What electrical tests are required for EV charging installations in Singapore?
Under SS638 and the specific EV installation requirements in SS555, an EV charging installation must undergo insulation resistance testing of all cabling, earth continuity testing, earth loop impedance (Zs) measurement, and RCD testing. The EV charger protective device must be verified to disconnect within the required time for the fault loop impedance of the circuit. All tests must be conducted by a Licensed Electrical Worker and results documented in the test schedule.
What type of RCD is required for EV charging points in Singapore?
EV chargers are a source of DC fault current components (due to the power electronics in the charger). Standard Type AC RCDs (which only detect sinusoidal AC fault currents) are not suitable for EV charging circuits. SS555 and IEC 61851-1 (the international standard for EV conductive charging) require Type A RCDs (which detect both sinusoidal AC and pulsating DC fault currents) at minimum. For DC rapid chargers, Type B RCDs (smooth DC fault current detection) are required. This distinction matters — the wrong RCD type will not provide adequate personal protection.
Does Singapore have a specific standard for EV charging installations?
Yes. SS555 (Singapore Standard: Code of Practice for Electric Vehicle Charging Systems) is the primary standard, covering both AC and DC charging, protection requirements, installation requirements, and commissioning tests. SS638 (the general electrical installation standard) also applies to the upstream electrical installation feeding the charging points. Both standards should be read together for EV charging work.
How often should EV charging installations be tested after commissioning?
SS555 and general good practice require periodic inspection and testing of EV charging installations — typically annually or as part of the building's periodic electrical inspection under the Electricity Act. Environmental exposure (outdoor charging points are subject to heat, humidity, UV, and occasional vehicle impact) accelerates insulation degradation, so trending insulation resistance values over multiple inspections is recommended.
What is the earth loop impedance limit for an EV charging circuit protected by a 32A Type B RCD?
The maximum permitted earth fault loop impedance for a 32A circuit depends on the protective device type and the required disconnection time. For an EV charging circuit with a 32A MCB (Type B), the maximum Zs for a 0.4-second disconnection time is approximately 1.37Ω under SS638 Table 41. However, since EV charging circuits typically require RCD protection (not relying on MCB for primary fault protection), the RCD's trip threshold (30mA for personal protection) is the critical protection mechanism, and the Zs value becomes relevant primarily for verifying that the backup MCB will operate under a high-fault condition.
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