Support

I have had my Open EVSE for almost 3 years - and put a few MWh through it, but over the last 12 months or so I am getting a 'No Earth Ground' status in the log which stops charging - either for the night or for a few hours.

It is now happening so regularly we are struggling to keep up the the charging of 2 EV's in winter (where we mostly charge using our midnight to 6am cheap rate.

Is my understanding correct that this error comes from the CT across active and neutral detecting a miss-match in current? (as in some is not returning via neutral but being leaked to earth? or can it be caused by the  MID400 voltage monitoring circuit also?

It only happen once it is up and running, sometimes it will run all night (6 hours), sometimes it will fault after seconds, but generally it is after 1-2 hours.

What is my first step in resolving this? it is using the V5.5 board, with wifi and the 2 line screen, still on the original software (4.1.2 and 7.1.3)

Thanks, so it is this part of the circuit below that is the only cause of 'No Earth Ground' fault in the charge log?

https://openev.freshdesk.com/support/solutions/articles/6000052136-openevse-boots-and-displays-error-no-ground-earth-ground-

We are on single phase here - so of the two lines monitored that go through the relay, one (neutral) should normally be near the ground voltage (you will see a bit of voltage rise on neutral on a long cable run), and the other (Active) should be at ~240AC compared with ground. I assume it takes this in account, auto detects if you are on single phase or two phase, and it my case is expecting to see a 'high' (AC voltage not present) from the 'neutral' monitor, and 'low' (AC present) from the 'active' line monitor?

Will either of these changing states while charging trigger the 'No Earth Ground'?

The relay opening as you mentioned would see the active line drop to zero volts (output high) causing a change of state on the active line monitoring only. The neutral monitor output should remain high (AC not present) and not change state.

Alternatively, if the ground wire is cut before the EVSE (which is what I assume it is designed to detect), you would expect to see both lines 'live' compared with the now floating ground (It would presumably float somewhere between active and neutral). This would cause the neutral line monitoring to go from high to low (AC not present to present) and would trigger it? The 'active' line  monitoring would remain low (AC present). 

That then suggests, if I am getting an excessive voltage rise in the neutral line (from a bad connection, running too much current in a long cable etc), it could be detected as AC being present (output low). The data sheet seems to suggest somewhere around 5VAC could be enough to trigger it in some conditions, and would be treated as a 'No Ground Fault' situation.

I upgraded to 7.13 last night (before your response), and cleaned up the GPO connections, it ran though the night at 13A for the first time in ages (the previous night it tripped after a few hours at 10A). I assume the software upgrade should not have made any difference in detecting a ground fault - as this is not the software that does the real time control of the charging and fault detection, it is just the WiFi/graphics side of things?.... though may have potentially made things worse if it is commanding a lower power setting the relay is not holding properly? 

I will see if I can upgrade to 8.2.2 tonight, if not I will up the relay power just to be safe. Keen to know if a neutral voltage rise can trigger it - in which case I will start monitoring the voltage to see if I have a wiring issue in the house.