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How to protect critical cabling for EV charging points

Alex Smith

Alex Smith

Technical Director at Flexicon Ltd
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Electric Vehicle Charging

No matter how many chargers are installed, they need to work reliably, that’s why protecting the cabling should be of utmost importance, according to Alex Smith, Technical Director at Flexicon. 

The government has set ambitious targets to ban the sale of new petrol and diesel cars from 2030, with the aim of moving the UK to an all-electric fleet as part of a package of green initiatives.

According to Which, most electric car charging happens at people’s homes, but not every household has a driveway. It states that ‘to help make electric cars a viable option for more UK consumers, the public charging network needs to become larger, simpler and much more accessible than it is today.’

Major and ongoing investment in the UK’s electric vehicle charging capability will be required over the coming years. While the Government has outlined some new investment in electric charging points, including grants of up to £14,000 for businesses, serious consideration must be given to the longevity of the electric cable infrastructure supporting these installations. 

According to Gov.uk, charge point reliability can be poor, with on average one in every 25 charge points out of service. Vandalism is also a potential growing concern, with many drivers reporting that when they do find an accessible charge point, that it is waiting for repair. 

This, coupled with a serious shortfall in the number of charge points available – forecasts suggest at least more than 10 times the current number will be required by 2030 – it is easy to see why motorists are frustrated with the lack of reliability and accessibility.

So, what cable protection considerations do the electrical contractors that will be tasked with installing the nation’s EV charging infrastructure need to consider? Well, we will cover areas such as resistance to compression, speed of installation, material specification and ingress protection (IP) ratings.

Reliability is key for a growing market

In its report published on November 22, 2021, the Department for Transport states that there are 650,000 plug-in vehicles already on UK roads, 250,000 home and workplace chargers and 26,000 public charge points already available in the UK. It goes on to outline the Government’s vision to ‘put in place a regulatory framework for charging that supports a nationwide network of reliable, accessible and easy-to-use infrastructure.’

It is this area of reliability that will be a key issue for the UK’s EV charging infrastructure, if the Government is to enable a network that is robust and fit for purpose. 

Protecting electrical cabling for longevity

The correct solution can be instrumental in protecting uptime and avoiding unnecessary cost. Cable protection should be specified as a complete end-to-end system, considering not only the flexible conduit used, but the range of termination and fittings used too.

One of the first areas to consider is the range of external hazards that the cables and infrastructure may encounter. In most applications, the EV charging point will be installed outside and exposed to the elements, with the electricity supplied through cables running underground.

These cables will typically be buried in concrete, with a platform or pre-cast slab supporting the charging point above. The flexible conduit solution specified must therefore have excellent resistance to compression, as well as considering the highly corrosive nature of the concrete itself.

Polypropylene conduit can be an ideal option in this scenario, as opposed to metallic systems. With high impact strength and abrasion resistance, the material also provides good electrical insulation and weathering qualities.

Of particular importance is the conduit’s resistance to corrosion. This can occur if the concrete starts to degrade through exposure to chlorides present in water or through carbonation, which affects the natural alkalinity of the concrete.

Polypropylene conduits are proven to offer excellent chemical resistance, particularly to aqueous solutions of alkalis and salts present in this scenario.

Ingress protection

The network of public EV charging points will also be subjected to a range of other environmental factors.

Exposure to water ingress and extreme temperatures are commonplace and the effects of these can result in premature product failure, which in turn leads to increased downtime and operating costs.

The BS7671 18th Edition Wiring Regulations specify that socket outlets should be placed at a height of 0.5 to 1.5 metres from the ground. To prevent external influences, cable protection could be added to enhance protection in the presence of water or solid foreign bodies above the IP44 minimum requirement.

If specified correctly, there are a range of suitable flexible conduit system alternatives that can offer effective cable protection. 

Of course, not all EV charging points are intended for use by the general public, with some businesses starting to take advantage of the Government’s grant scheme and installing wall or surface mounted units for their employees.

Simpler to install, cabling for these units may be run through an external wall, using mechanically protected cabling such as SWA cabling. Metallic systems can provide rugged mechanical protection, with IP54 or IP65 for greater ingress protection combined with high flexibility. This can be further uprated by using liquid tight conduits for IP68 and IP69.

Retrofitting options

As the EV charging network becomes more established, installed units – and their electrical cabling – will require routine maintenance to ensure ongoing reliability. 

This may require cable protection to be upgraded; traditionally a complex and lengthy task, with the installer required to pull existing cabling through the open end of a conduit system. 

Divisible conduits are now making retrofitting much simpler. They allow existing cabling to be inserted laterally via a slit opening, which then interlocks to form a protected IP40 system around the cables for enhanced mechanical protection.

Building a resilient network for the future

As well as protecting the electric cabling running underground, it is likely that flexible conduit suppliers will play an increasingly important role in protecting the electric cables within the charging unit itself, working alongside manufacturers and OEMs.

Composite products such as plastic sheathing on metal conduits to increase the ingress protection, or metal over-braiding on non-metallic corrugated for EMC, or metal threads on plastic fittings can offer the ideal combination of light weight, high strength, and fast installation.

In conclusion, electrical contractors should discuss the range of options available with their cable protection supplier, who can advise on the most appropriate conduit system for the environment, based on the hazards the charge point will be exposed to.

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