OpenEnergyMonitor Community

OpenEVSE and wiring regs changes (722.531.2.101)

Forgive me for jumping in on the end of an interesting discussion (and for being a bit of a beginner)

I was planning to install a Zappi-2 (when/if it becomes available) but after many promises of an end user API over the last year my hopes were finally dashed with an email from one of their directors confirming they will not be developing one so I have cancelled my deposit.
Looking for alternatives I came across your EVSE which ticks all boxes but this thread concerns me.
I have a TN-CS site. While £550 is a saving over the Zappi, adding a £300 type B RCD is a bit of a sting in the tail. Is this just something I have to accept or is there any other option?
Apart from the RCD issue, is there a reason why your EVSE steps up and down in 1A steps? The Zappi seems to follow the export CT to within about 50W. Here I am going to expose my ignorance about the PWM signalling but is this something that can be improved in future?

Hi Steve,

I’ve just been in communication with our OLEV installer and their electrical supplier. They use a Chint NL210 Type-B RCD which meets the requirement not to be blinded by 6mA of DC leakage. This RCD costs less than £120. We will be getting stock of these RCD’s to sell with our units in the next week or so.

If you are interested in getting an EmonEVSE unit installed under OLEV I would recommend contacting EcoPlugg for a quote.

We are working on integrating DC leakage detection into our unit, but this is probably about 6-12 months away and will probably add about £100 at leat to the cost of the unit.

1A control resolution is the J1772 protocol supported by all EV’s. Zappie or any other EVSE won’t be able to control the charge rate at any higher resolution since this is a hard limitation of all EV’s. Also the minimum charging current of J1772 is 6A approx 1.4kW.

For more info on J1772 see: OpenEVSE SAE J1772 Theory of Operation : Support

Thank you for the fast response Glyn. I certainly will look out for your affordable type-B RCDs. Will they appear on the shop as optional accessories? Sadly I cannot take advantage of the OLEV grant as I have used my allocation, first with a PodPoint five years ago and the second time with a Zappi about two years ago.
The Zappi really does manage higher resolution changes, certainly with the Golf and the Kona we run here but it isn’t a huge issue as we now have a couple of Powerwall IIs which can absorb/support the gaps. It may be that some cars go beyond the J1772 PWM standard although I concur with the 6A lower limit. That is where the Zappi cheats a bit, allowing you to set a %age of “greenness” permitting EVSE startup when PV is <6A.
I’ll temporarily disable the batteries the next time we get a sunny day and plot the PV against the export and post it here.
I have never tried playing with MQTT so am looking forward to control the EVSE max rate based on the PWs SoC and the Octopus HH tariff.

Yes, hopefully in the next week. I’m just waiting on supplier to finalise pricing.

Actually, I think you could be right. The PWM could be controller to a higher resolution. The limiting factor would be the onboard charger. I will do some testing and investigate if the openevse controller could in the future be firmware upgraded to support higher resolution.

Yes, there are lots of possibilities for automation and integration. Using NodeRED is a popular option.

Hi all
Came across this link
Voltimum news
Which states

From January 2018, IC-CPDs manufactured to IEC 62752:2016 used in Mode 2 charging cables , had to include the facility to detect DC residual currents and disconnect if > 6mA DC

This would make it difficult to sell plug-in versions of OpenEVSE without the type B rcd.

Look forward to £120 rcds as I can only see them over £200 :grinning:

Interesting, thanks for the link. The OpenEVSE is not sold as a mode 2 unit. We are working on integrating DC current leakage detection. In the meantime we have sourced some reasonably priced type-B RCDs:

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Apologies in advance, if my post doesn’t make any sense.
Like many others I have been looking at openEVSE as an option, but worry about the need for TT island’s earth rod.

I noticed this article about amendments to the 18th edition, which I am sure you are very well aware:

Is this something the OmonEVSE unit is likely to support?

We are investigating EmonEVSE hardware upgrades to negate the need for an earth rod, however I cannot give you a time frame on this.

If an earth rod installation is not possible, a Matt-E device to provide an earth disconnect under fault condition:

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Hi, is it correct to say that to comply with new regs (18th ed. amendment 1) openEVSE outside should be installed with:

  • Type B RCD and Earth rods
    *Matt:e (or similar device like Garo G6EV40PME).

Should internal GFI be removed?

Hi @roberts
Short answer yes but not just outside. All EVSE now need to have open PEN protection whether inside or out.
The Matt: e or similar just removes the need for TT earth (rods).
You will always need the functionality of type B rcd (for DC fault protection). Some EVSE has this built in. As of last year OpenEVSE didn’t (but I’m not up to date with that)
I believe you don’t need to remove the internal GFI/RCD - why would you want to?
FWIW the Matt:e variant with type B rcd is the SP-EVCP-B

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I will follow this thread with interest given I’m in the market for a 3 phase EV charger

Thanks for the comment @EskEnergy - it’s nice to talk about those things with other people who are interested in electric vehicles!

I was asking about removal of GFI because I remember seeing somewhere a note to not to disconnect it. I was wondering if it plays a part in functionality of the equpment - e.g. check to allow charging to start.

Regarding other comments, there are few common misconceptions for domestic installatons I think I should address.

  1. “Open PEN detection device is required for all EVSE whether indoors or outdoors.”

Those devices are not a requirement in BS 7671:2018 (+A1 2020) at all. In fact 722.411.4.1. says that PME supply should not be usd for EVSE outdoors unless one of five conditions is met, where this Open PEN detection device is just one of the options.

  • If the vehcle is charged outdoors there are other options, for example, installing additional earth electrodes, converting existing installation to TT, TT system for EVSE only or isolation transformer.

  • Open PEN detecion device is never needed if the EV is charged inside and there is no posibility to use it while EV is outside. CoP 6.7.1. repeats that PME can be used within a building without rods (or open PEN devices for that matter), but gives aditional suggestion that non-extended tethered lead only should be used (key - you should not be able to be in contact with true earth and PME earthing).

  1. “Type B RCD is needed for DC fault protection”

722.531.3 specifies what type of RCD is needed for EVSE. That is:
*Type B RCD or
*Type A or Type F in conjunction with RDC-DD.

From my experience if Type B RCD is not installed, Type A RCD is used together with a residual direct current detecton device (RDC-DD) that can detect if the DC component exceeding 6mA and disconnect the supply. Those devices might be built-in in EVSE or can be installed seperatly.

  1. Regrding Discrimination.

In 18th edition it is called Co-ordination or selectivity. Yes, if you install RCD in your EVSE distribution board you might have issues with coordinaton with RCD/GFI. CoP recognizes that sometimes it might not be practicable to folow it. This is the reason why I was asking if GFI is required for functionality of the OpenEVSE.


I consider my wrist suitably slapped!

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I have managed to integrate the Western Automation RCM14-03 module into the OpenEVSE unit.

This gives AC 30mA and 6mA DC GFCI protection (tested and confirmed). While there are several methods of integrating the module…I wanted to simplify the integration so that DIY builders can easily upgrade their units without having to make modifications to the actual controller board or firmware.

The RCM14-03 gives a ‘HIGH’ output on its [FAULT] pin via a pull-up resistor when leakage is detected.

This [HIGH] signal can be directly coupled to the sensor input (pin 2) on the GFCI connector. The value of the pull-up resistor is selected (1k2) to level shift from 12V operating level to the 5V input of the GFCI detector.

I added an ‘exciter’ coil to the RCM14-03 so that the self tests will run without issue. I also made a custom cable with integrated pull-up resistor so that the module can be fitted easily to the controller board.

I received great support from the R&D department of Western Automation who are the manufacturers of the necessary modules.

Please see pictures attached.

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Just been reading this brilliant thread and would like to add that in the COP for EV 5.2.3 unless it can be guaranteed that the supply is TNS back to source, ie your own transformer. TNS should be treated as TN-C-S.

Very good.
Thank you for sharing!

Nice work! That’s very tidy integration. Have you been able to find a source to buy the RCM14-03? Will westernautomation sell direct? I can’t see any pricing info on their website.

Nice work on the DC earth fault workaround. Did anyone find a good supplier (cheap) for the RCM14-03 in Europe at reasonable pricing? Are there any other supplier in the market for similar than Stegen?

We notice that Go-e Charger is using the Bender RCMB121, could not find pricing anywhere on their coil. Has anyone looked how difficult the integration to OpenEVSE would be?

It would be great if this could be made to work with the openevse system, though squeezing this is the case would be fun :slight_smile:


Great integration Cyril! RCM14 module needs 12v to operate and my question is did you take 12v from OpenEVSE controller board? I have OpenEVSE v 5.5 but unfortunately the 12v output is used for WIFI module.