Electric vehicles: 18th Edition EV chargepoint

May 18, 2023

EV Installers are responsible for checking that equipment and products they install in the UK, meet the appropriate product standards and the requirements of BS7671, before they sign-off the Installation. In principle this seems straightforward but in practice what does this mean regarding correct completion of the Electrical Installation Certificate – Section relating to RCD details and standards?

Documentation?

Installers can protect themselves by following the exact requirements of BS7671 relating to design, install, inspection and testing. Having a clear understanding of the different standards (headings) referenced in BS7671 associated with RCD protection and EV chargepoints, is prerequisite to knowing what to look for when selecting chargepoints. It does not cost anything to check the BSI website for an overview of a relevant standard.

30 mA RCD protection built into mode 3 charge points: BS7671 722.531.3.101 specifies that the RCD protection must meet specific standards (discussed in detail later). Some manufactures are making misleading claims in their documentation. It would be hard to believe this is deliberate, but then it demonstrates a lack of understanding of the relevant standards. This can lead to the installers, making a false declarations on the associated installation certificates and worse, providing ineffectual protection for users of the chargepoints.

The section in the installation certificate relating to RCD protection, refers to RCDs that meet the standards specified in BS7671:

Any departures from BS7671 e.g. using products that do not meet the standards* must be recorded separately – see 120.3, 133.1.3, 133.5.

Note the requirements of Reg 133.1.3: Append a declaration to the test certificate giving full details of the deviations and why i.e. BS7671 requires that “… the equipment provides the same degree of safety as that afforded by compliance with the Regulations.”

*In practice an Installer would be ill-advised to take on the responsibility for the design performance of equipment that does not meet the existing standards - see Reg. 133.1.1 . However some do, all be it unwittingly. Several European countries are clamping down on charge-point manufacturers misleading documentation and associated products, resulting in products being removed form sale by wholesalers.

Inspection, Testing, Installation Certificate.

How to verify that the product is safe for use in accordance with BS7671:

642.1: This inspection clarifies that the equipment and the installation conform to the appropriate standards for the UK. Checking electrical equipment before it is installed saves time and money.

642.2: Verify that equipment complies with the requirements of 511; namely every item of equipment shall comply with current appropriate BS, EN or IEC standards. Verified by reference to the Manufacturer’s current UKCA 2023 documentation issued in the UK.

There is a risk that EV equipment that is already in the supply chain could be out of date and or subject to modification, such as a change to the manufacturer’s installation instructions. Technical information on an intermediaries website may not be up to date. Verify that you have the chargepoint manufacturer’s current documentation and supporting UKCA D of C. These are obtained from the manufacturer (if they have a UK base), or their legally recognised UK Agent / Importer. The latter are legally responsible for products placed on the UK Market, sourced from manufacturers based outside mainland UK.

133.1.1: An RCD installed in the chargepoint be it a product or integrated function, must meet the full requirements of 61008, or 61009 as appropriate. Check the manufacturer’s current documentation and small print to verify the RCD meets the correct standards. If in doubt fit an external RCD to the appropriate standards required by BS7671.

For those of you who are new to the industry, performing a simple RCD tripping Test to 643.7 on the output of an enclosure, does not prove that the box contains an RCD. You must verify by following the correct inspection procedure detailed in BS7671, as you would with any consumer unit / garage unit. A mode 3 chargepoint is effectively a consumer unit with a socket or cable attached to it, plus some electronics for controlling the charging function / smart charge etc.

BS7671 722.531.3.101 RCD or RDC definition?

Understanding the basic terminology associated with EV charging is a prerequisite to making informed and safe decisions regarding equipment.

As with RCDs, RDC-DDs (Residual Direct Current Detection Devices) are classified according to the functionality they provide. The acronyms RCD and RDC-DD are similar, but their functions are different and can easily be confused by the unwary or inexperienced.

RCDs: Provide fault protection and additional protection as defined in BS7671 – It is easy to assume incorrectly that RCDs are only associated with fault currents in the mA range. RCD contacts in combination with short circuit protection (internal or external to the device), must open safely and electrically isolate the circuit when subjected to any fault current, up to the breaking capacity of the combination.

Referring to RCDs as “Electronic” as opposed to “Electro-mechanical” displays a limited knowledge of RCD technology. Any RCD used in association with EV charging applications will contain electronic components, and all RCDs must use electro-mechanical contacts to provide galvanic isolation. There are no “electronic” components in general use that provide galvanic isolation.

The standards classify RCDs as fault breaking devices, the contacts and chambers must be designed accordingly to handle a specified range of fault currents safely and reliably without welding. Isolation contact gaps for RCDs are greater than those required for small contactors and PCB mounted relays, used in most EV charger designs. Short circuit breaking tests required by the RCD standards (61008 or 61009), verify that the circuit is electrically isolated following a fault. Doepke and other reputable RCD manufacturers have their devices certified by 3rd parties such as VDE.

BS7671 specifies that RCDs used in UK installations must meet one of the following standards 61008, 61009 or 60947-2. This also applies to EV chargepoints – see 722.531.3.101. Note 60947-2 relates to CBRs; not for use by ordinary persons.

RDC-DD: The primary function of RDC-DDs (IEC 62955) for use in Mode 3 charging applications, is to detect low values of smooth DC fault current and disconnect the circuit. Smooth DC fault currents (this includes fault currents with a time base < ½ cycle that do not pass through zero), can saturate the induction technology used to monitor AC residual currents associated with the AC supply voltage.

62955 defines two basic classifications of RDC-DDs:

RDC-MD: The M stands for MONITORING.

RDC-MD: There are 3 sub classifications (forms of product configuration defined in the standard):

It is common practice for chargepoint manufacturers to purchase a separate DC current sensor and combine it with a contactor or PCB relay to perform the switching function (RDC MD 4.1.1.1).

The chargepoint manufacturer is then responsible for carrying out the product verification / testing on the combination of current sensor + switching device to the requirements of 62955. Chargepoint manufacturers who do not test to the standards, cannot provide the verification specified in BS7671.

Clause 9.11.2.3 of 62955 for RDC MDs, specifies that the combination + SCPD (specified by the manufacturer), must be subjected to short-circuit tests. These tests verify that the RDC+SCPD can withstand without damage short-circuit currents up to the rated conditional short circuit current Inc. The combination must be suitable for re-use after the tests i.e. the contacts must not weld and the insulation voltage must be maintained. The minimum value of Inc allowed in the standard is 500A i.e. the maximum value of prospective fault current at the point of installation for chargepoint with this characteristic. Many small contactors and relays associated with EV chargers have a high risk of welding and would not be suitable for re-use, so these test are particularly important when verifying the design.

IEC 62955 specifies that RDC-MDs must be used in combination with an RCD conforming to 61008 or 61009 to provide 30 mA protection.

Note:

61851-1 Clause specifies that relays meet 61810-1 and or contactors meet 60947-4. Both these standards recognise the high risk of contact welding when applying these devices – see Risk Assessment recommendations in these standards. Designs subject to the correct risk assessment proposed by the standards, would highlight the design weakness of using these contacts for electric shock protection.

RDC-PD: The P stands for PROTECTION.

These devices in addition to 6 mA smooth dc detection provide 30 mA residual current protection and isolation under fault conditions: For example the contacts must be mechanically linked to ensure disconnection of all live conductors e.g. for an RCCB clause 8.1.2 of 61008*

*Annex O of 62955 states that the tests on the RDC-PD to the relevant RCD standard “apply without modification”.

Contactors or relays would not pass the full test requirements of 61008 or 61009.

BS7671 722.511.101 EV chargepoints shall comply with the relevant parts of 61851-1:

“Nothing in all the world is more dangerous than sincere ignorance and conscientious stupidity.

Martin Luther King, Jr”

Example: The manufacturer of the chargepoint has failed to recognise the risks of using a contactor or relay contacts (not followed the full recommendations of the standards) in fault breaking applications – RCD not included in the circuit to provide additional protection as required by BS7671.

Think – if this was your house would you install a consumer unit with a two-pole relay, operated by a residual current monitor – in the place of a 2 pole RCCB – Without question - NO!

Read the small print before installing a chargepoint, without the associated RCD protection required by the standards – just imagine it is one of your family members charging their EV in the rain.

Standards referenced in BS7671 help Installers make reasoned and safe decisions:

There is close alignment between the chargepoint standard 61851-1, RDC-DD standard 62955 for Mode 3 charging and the associated RCD standards specified in BS7671. These standards allow for technical product developments, whilst maintaining basic electrical safety requirements, using tried and tested electrical theory and practice.

61851-1 Clause 8.5 specifies that RCDs used in the equipment shall comply with one of the following products standards 61008, 61009, 60947 -2* and 62423** for Type F or B if applicable i.e. the RCD is evaluated as a stand-alone device, to the appropriate standard.

61851-1 Clause 14 (C) UK only : 30 mA chargepoint RCDs must be manually reset i.e. they must not be automatically reset by the software in the chargepoint or remotely resettable i.e. reference BS7671 531.1.1; auto-reclosing of RCDs shall only be installed in locations where access is restricted to instructed or skilled persons only.

As explained earlier in the article, the reason for the above: RDC-MDs that use relay or contactors for load switching and switching low levels of smooth dc fault current, are not suitable for the provision of 30 mA RDC protection. They must be used with a separate RCD / fault breaking device that has been tested to 61008 or 61009.

*60947-2 relates to CBRs: Not suitable for use by ordinary persons – see 411.4.4, Note 2

**62423 Type F or B RCD test characteristics: Additional tests required to 61008-1, 61009-1, 60947-2.

Conclusion

Do not get bamboozled by Non-UK Manufacturers documentation, which pertains to provide RCD protection but does not make specific reference to the product standard required by the Regulations.

Some chargepoint manufacturers may claim that it is not a legal requirement to manufacture equipment to meet the recognised standards – correct. But there is a legal requirement to verify the design through the application of appropriate risk assessment, design procedures and performance testing before placing electrical equipment on the market.

The nominated Company / Agent importing electrical equipment into the UK is legally responsible for verifying that the equipment meets the appropriate Regulations e.g. Electrical Equipment (Safety) Regulations 2016.

Using recognised standards is a simple and safe way to verify the basic performance requirements and the longer-term safety of equipment. These standards must be applied in full as appropriate to the safety of the equipment or product e.g. If the manufacturer is providing 30 mA RCD protection, the product must meet the associated RCD standard in full i.e. during an MOT you cannot ask the garage to check the tyres but not the brakes. Ask the manufacturer to provide current UKCA Declarations of Conformity listing the standards they are claiming they meet. If the D of C does not refer to the RCD and RDC-DD standards referenced in BS7671, separate devices would be required to meet the recommendations of BS7671.

Purchasing and installing non-conforming electrical equipment places the onus of responsibility on the Installer, to verify that the equipment provides at least the same degree of safety as equipment manufactured to the applicable standards – see 7671 133.1.3.

In practice it would be impossible for an Installer to achieve this without access to a specialised design and testing facility with appropriate design knowledge, standards, and test equipment.

To meet the requirements of BS7671, mode 3 chargepoint equipment must meet 61851-1 . Both these standards require that 30 mA RCDS used in or with the equipment meet 61008 or 61009 as appropriate.

Chaz Andrews – Technical Manager, Doepke UK Ltd

[email protected] or www.doepke.co.uk