Supply Installer – Electric Vehicles

Technical Information

Electrical Earthing

An age old dilemma has presented itself to electricians over the years, whether to install an earth rod or use the suppliers earth when supplying electrical equipment remotely from the installation. 

PME vs PEN

The background: The vast majority of electrical installations use what is known as a PME supply (Protective Multiple Earthing).  This means the suppliers cable has 2 conductors one is the line (live) and the other is known as the PEN conductor (Protective Earth and Neutral), as the name suggests this 2^nd conductor combines the neutral and the earth in one, as it enters the property the earth is separated  and we now have our standard 3 conductors: line (live), neutral and earth. 

Problems and Solutions

The problem: The issue here is if the PEN conductor is open circuit (ie. severed by a digger) the electrical installation still continues to function, however, there is now no official neutral return path. There are still paths available for the current to flow and those are via anything connected to the main earthing terminal  such as the gas/water pipes or if you’re lucky enough to be standing in good contact with the earth and touching an earthed electrical appliance (large electric vehicle for instance) even you, which needless to say could be potentially fatal.

The solution: The electricity supplier replaces all of their 2 core cable with 3 core cable! Oh no, hold on, that would cost a considerable amount of money and they like to keep they’re costs down, the risk is fairly low 1 in 1,000,000 that’s the excuse… hmm surely someone wins the lottery most weeks?.

Ok so no fairytale solution back to the installer…

Zappi and Pod Point

 2 options exist either ditch the suppliers earth installing an earth electrode (rod) and creating an independent earth or install  equipment which has been designed to detect this type of fault and automatically disconnect the supply to the electric vehicle. 

Hence we are back where we started with the Pod Point and Zappi manufaturers who have incorporated this piece of technology into their equipment saving the contractor installation time on installing earth rods and the client money on the install cost whilst allowing the continued use of the suppliers earth which is of much greater use when you have an actual fault than an earth rod.

The Zappi V2 range manufactured by Myenergi, is designed to work intuitively with a  home energy generation system such as a solar PV (photovoltaic) system as well as battery storage. Using the myenergi app users can see in real time the energy usage/generation within their household, the Zappi can be configured so that it only uses surplus energy which would otherwise be sent back to the grid. This allows the client to charge with 100% green energy. If additional power is required this can be backed up by the stored energy or grid supply as last resort.

We are not averse to installing other types of charge point and if the client is particular to another make and model we will look to accommodate this if it is suitable.