Phil, NOPE! The *correct* designed EVSE will have a test circuit that indeed generates a GFCI test fault current but *only* in the EVSE's GFI circuit, not in the upstream 240V connection. The reason that an EVSE often trips the upstream GFCI is not due to the EVSE but due to the *huge* capacitance in the EV charger inlet which can easily cause enough fault current, just like many lab equipment has large filter capacitors on their AC input to filter out EMC, but at the same time tripping the GFCI to the point that you cannot even leave some bench power supplies plugged into the wall, even turned off, because their AC filters will happily cause more than 5mA current through their heavy capacitors and nuisance-trip the breaker.
For the EVSE to test their built-in GFCI protection of the *downstream* charging cord, all that is needed is that the test circuit connects a wire (and resistor) across the 2 phases of the 240V so that there is *no* upstream fault current, and then route the test wire through the GFCI detection Current Transformer, so that a one-way fault current is introduced of between 20-30mA, while verifying that the detection circuit indeed trips on the application of the test current. (The GFCI Current Transformer has both phase wires of the charging cord routed through it, so that any difference of more than 20mA between the two wires - even at 40A or more of charging current - will cause a trip of the GFCI detector and disconnect the relay contacts that feed the 240V input to the charging cord.) In the JuiceBox charging station I only used a 4mA test current, so I could use a smaller and cheaper limit resistor, by looping the test wire 5x through the GFCI CT coil, so the 4mA was counted 5 times to yield the 20mA test current injection to verify the correct operation of the GFCI after *every* charging session, as well as during boot-selftest. You might notice that the JuiceBox (at least the plastic JuiceBox 2) is also UL approved for operation on 110V and it was a challenge to make the GFCI test circuit still generate a 20mA test current no matter what voltage that the EVSE received. If you figure it out, let me know what you found and I will tell you if you got it right. Cor. On Fri, Apr 12, 2024 at 12:14 PM (-Phil-) via EV <ev@lists.evdl.org> wrote: > > IIRC, J1772 specs 20ma. So it will likely put an over 20ma ground fault > intentionally during its self test. > > On Fri, Apr 12, 2024 at 12:01 PM EV List Lackey via EV <ev@lists.evdl.org> > wrote: > > > On 12 Apr 2024 at 13:35, Mark Hanson via EV wrote: > > > > > An HTML attachment was scrubbed.. > > > > Thanks Phil etc > > > > Sometimes the code doesn't explain why there's certain rules that appear > > arbitrary (like the 12" cord rule). The larger units are limited to 6'. > > > > Presumably the GFCI trip current (inside a EVSE) is higher (not sure how > > much) than the 6ma (if using a GFCI panel breaker). A large chassis like > > a > > car and with an internal switching supply-charger has EMI X (line to line) > > and Y caps (line to ground for common mode RF) that will most likely leak > > close to 6ma. Luckily inspector 13 (here) hasn't enforced the panel GFCI > > breaker requirement (since 2020) on 14/50s used for EV charging. > > > > Best regards Mark > > > > PS from the moderator - please try to send plain text, folks. Thanks. > > > > David Roden, EVDL moderator & general lackey > > > > To reach me, don't reply to this message; I won't get it. Use my > > offlist address here : http://evdl.org/help/index.html#supt > > > > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > > > > The phrase "May you live in interesting times" is the lowest in > > a trilogy of Chinese curses that continues "May you come to the > > attention of those in authority," and finishes with "May the > > gods give you everything you ask for." I have no idea about > > its authenticity. > > > > -- Terry Pratchett > > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > > > > _______________________________________________ > > Address messages to ev@lists.evdl.org > > No other addresses in TO and CC fields > > HELP: http://www.evdl.org/help/ > > > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20240412/68fe2494/attachment.htm> > _______________________________________________ > Address messages to ev@lists.evdl.org > No other addresses in TO and CC fields > HELP: http://www.evdl.org/help/ > _______________________________________________ Address messages to ev@lists.evdl.org No other addresses in TO and CC fields HELP: http://www.evdl.org/help/
