EV Fixation: Why pre-scanning is so important | Gary Alder, Tideway


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Gary Alder, CEng MIET-BMBJV, Tideway Electrical Officer, looks at why it is important to conduct a proper site survey before installing EV charging stations. In 2020, the National Grid reported that if every car became electric overnight, there would be a 10% increase in the country’s total load consumption. This is alerted provided load management is in place, but what other considerations need to be taken into account for EV charger installations? Start with a Survey The main place to start is always a property or site survey. UK power grids have the right to refuse car charging installations. Applications, which require an increase in installation in excess of 60,000 MAs, are required in advance of any installation work being completed. Even if the maximum order does not exceed 60 amps, approval is still required and can be completed within a 28 day notice period after installation. The order form will require information about the installation, such as incoming valve fitting details, voltage measurements, and more. It is very helpful to ensure a thorough pre-inspection of pricing and completion of installations, including checking the condition of the consumer unit, protection devices, and mains connectors – all the daily activities that electricians perform anyway. A major consideration will be the UKPN’s grounding system on the property. It is noteworthy that within the UK Power Grids Grounding specification, EDS006 B.4 states that all TN-S supplies are considered TNC-S, due to the use of concentric cables within the UKPN network, not just the supply head visible in the property. The next consideration will be the type of vehicle and the method of charging required. Usually, we’d expect to see a battery or hybrid vehicle, but it’s always worth checking the manufacturer’s instructions and instructions if any details are needed. Dedicated circuits are a must, as charging type 1 type (use of unallocated circuit and socket outlet) is strictly prohibited. Most chargers will operate within a 7.4 kW load range with Type 3 charging mounting, giving you approximately three to six hours of charging. What other loads are in the property? As mentioned earlier, National Grid expects most installations to use some form of load management. While it is an Office of Low Emission Vehicle (OLEV) requirement to provide energy management when receiving grants for installations, there is still a formal requirement to do so. Some manufacturers of electric vehicle chargers already include current transformers, providing the ability to stop charging the vehicle while using large loads inside a property, such as an electric shower or oven. An alternative is load management distribution equipment (shown in Garo distributor units, for example), which provides the same principle. Choosing protective hardware is always a major component of an installation. At the site survey stage, you may notice a residual AC device in existence, which will not provide adequate protection for the new circuit that is about to be added, thus incurring an additional cost for a Type A or Type B device. Then we come back to the issue of grounding. Considerations should include evaluating other circuits near the charger and where the electric vehicle might be parked. You must also complete a concurrent connection assessment. There are ways to solve these problems, by using equipment such as transformer isolation. However, these can be small pieces of gadget that a consumer may be reluctant to possess in the property. Most installations currently use O-PEN devices (in accordance with BS60255-1 for current sensing relays) to measure voltage disturbances between line and neutral. Consider surge protection when supplied from Henley blocks, due to some of the previously mentioned limitations, it is also worth considering an surge protection device, as it can be defined as a separate installation, as per the definition given in BS7671. All major considerations lead to one point: no two installations are the same. As such, a thorough site survey can ensure that you are well prepared for any eventuality.


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