zappi 2 – BS7671 includes a number of features to ensure that it is safe in all circumstances.
As well as the built in RCD protection, zappi 2 includes built in protection against damage to the main cable feeding the property – sometimes referred to as “PEN Fault Protection” as it refers to the protection needed if there is damage to the combined Protective Earth and Neutral (PEN ) conductor on a TN-C-S (PME) installation.
In the UK, the rules covering electrical installations are defined in the Standard BS7671:2018.
In February 2020, BS7671 Amendment 1 was published. Zappi 2 meets these new requirements in full and can be installed without an earth rod on both single phase and three phase systems.
You may also be interested in this ->video<- which explains why PEN protection is so important and why we are confident that Zappi 2 is the safest EV charge point available as well as being one of the simplest to install.
What changed in Amendment 1?
There are three important changes that we would draw out
1. A new clause has been added to clause 722.411.4.1 (clause v) which covers the PEN Protection feature built into zappi v2. This covers both single phase and three phase versions of the zappi and clarifies the position in the original drafting of the Standard.
Zappi is fully compliant with this new clause in BS7671:2018 for protection against loss or damage to the PEN conductor, and can be installed without the need for an earth rod in single phase and three phase systems.
The built in PEN protection also protects against any potential injury from electric shock without any time delay – other protection devices may take up to 5 seconds to operate even though they comply with the amended Standard.
2. The Amendment now allows a simple Line-Neutral voltage measurement to provide (some) protection against the potential for electric shock following damage to the PEN conductor on a TN-C-S system (clause 722.411.4.1 (iv)).
We have previously shared our serious concerns about this approach as
- it does not provide protection against a potentially fatal electric shock in all circumstances. See this video made by e-Fixx and this information on our web site https://myenergi.com/pen-protection/ for a detailed explanation.
- In the updated guidance notes that the IET will be publishing in March they actually admit that this is the case.
- the proposed upper voltage limit for the protection to operate (253V) also means that there will be a lot of spurious tripping of charge points that use this form of protection – we have recently carried out some analysis on the voltages measured on a sample of our devices (part of the FRED trial) and it likely that a significant number of these would have tripped due to extended periods where the line voltage is >253V
On this basis, zappi remains the safest and most reliable EV charge point available:
- It trips instantly in all circumstances to protect against a potentially fatal electric shock
- It will not suffer from spurious trips when the system voltage is high (or low)
and of course it is one of the simplest to install as well as being packed with smart features and the built in integration with PV systems!
We hope that you agree with us that a simple voltage trip is not the right approach, particularly if you install a competitor product and then discover your EV is not charged as the charge point has tripped…
3. For the first time, the Amendment makes it clear (in clause 722.311.201) that “load curtailment” may be taken into account when determining the maximum demand of an installation.
- This means that the installer no longer needs to do a maximum demand and diversity calculation provided the charge point has a grid limit that is set to the DNO fuse rating
- It also means that the installer may not have to apply to the DNO for permission in advance to install the charge point.
Zappi has always had this fuse protection feature built in – again making the installer’s life as straightforward as possible
We have put together more information on the Grid Limit function under the Resources section of our web site at https://myenergi.com/zappi-2-grid-limit-function/, including a document that can be sent to the DNO if they have any questions.