T E C HN I CAL
Electric vehicle charging installations regulation also stated that the requirement of this regulation need not be applied for the charging point at a dwelling1, if none of the conditions (i), (ii) or (iii) was reasonably practicable. This exception no longer exists in the 18th Edition. It is now incumbent upon the installer of an EV charging point to comply with one of the three conditions given where the protective measure of ADS is applied to an installation having a PME earthing facility, or to ensure that in the event of an open-circuit fault in the supply PEN conductor, the touch voltage2 does not exceed 70 V rms.
O B JE C TIVE
The aim of this article is to highlight the changes that have taken place in Section 722 with the introduction of the 18th Edition of BS 7671. The particular focus will be on the changes to Regulation 722.411.4.1 concerning the use of a PME supply to domestic premises. The requirements for RCDs, socket-outlets and connectors will also be mentioned.
Requirements where the supply is PME This article supplements the two written previously for Connections as detailed below. • Issue 188 – Amendment 2 to BS 7671 – Electric vehicle charging installations • Issue 189 – Charging systems for electric vehicles
Where a PME earthing facility is provided, Regulation 722.411.4.1 places conditions on its use as the means of earthing for an electric vehicle charging point located outdoors or that might reasonably be expected to be used to charge a vehicle located outdoors.
Introduction The fitting of dedicated electric vehicle charging equipment is a significant addition to an existing installation. As with any addition or alteration, Regulation 132.16 requires the adequacy of the existing equipment including that of the distributor to be assessed. Some Distribution Network Operators (DNOs) require the installer to complete an Electric Vehicle Notification Form informing them of the intended loading. A load survey can then be carried out to calculate the new maximum demand after diversity (ADMD) at the property to ensure that the DNO’s equipment is adequate for the additional load. Regulation 722.411.4.1 of the 17th Edition AMD3 precluded the use of a PME earthing facility as the means of earthing for a charging point located outdoors or which might reasonably be expected to be used to charge a vehicle outdoors. However, this
Condition (i) For this condition to apply, a three phase installation must exist, triplen harmonics must be small and the following condition must be met: Im×U0 70≥I +I +I L1 L2 L3 1 The term ‘dwelling’ means a self-contained unit designed to accommodate a single household. 2 Whilst there is no definition of ‘touch voltage’ in Part 2 definitions of BS 7671, it can be taken as the potential that appears between an exposed-conductive-part under fault conditions and the general mass of Earth.
Where: Im is the maximum neutral current U0 is the nominal AC line voltage to Earth IL1/2/3 is the current in each of the line conductors The maximum neutral current, Im, occurs under conditions of maximum imbalance between the phases and not the maximum overall demand. This means that should an open-circuit fault occur in the supply PEN conductor, the maximum voltage
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