The GFCI topic

[TEG]

A GFCI (Ground-Fault Circuit Interrupter) is a device inline with a power cord that attempts to detect wiring faults further down the line. If it thinks some of the current is "leaking" then it will disconnect the power. This is meant as a safety system so, for instance, if you were standing in grounded water, and touched one of the energized leads it would try to quickly stop the power flow.

Sometimes GFCIs can be touchy and trigger in cases when the circuit is basically working but there was a momentary anomaly.

More information about GFCIs:
Residual-current device - Wikipedia, the free encyclopedia
HowStuffWorks "How does a GFCI outlet work?"
False GFCI Tripping

Related posts:

The MC240 draws 30 amps only because there are no 40 amp GFCIs for Tesla to use. So they use a 30 amp GFCI and limit draw to 30 amps. Once they can source a 40 amp GFCI, the MC240 will be upgraded to 40 amps.

I just had the firmware 3.3.1 update to address the MC120 GFCI tripping issue... It still trips.

Stefano (stefspec) on Twitter

There is a new Tesla Roadster Firmware update that addresses nuisance GFCI tripping when using the Tesla MC120 mobile charge cord. Sweet!

A GFCI only looks at current differences between Line and Neutral for 110V apps, and between the two lines for 220V apps. For this reason, voltage differences between Neutral and Ground should not matter. If it did, then ground faults on other circuits would induce false alarms on good circuits.

From GFCI Basics:

A GFCI protection device operates on the principle of monitoring the imbalance of current between the circuit's ungrounded (hot) and grounded (neutral) conductor. It does not monitor the grounding conductor, and so it will still operate in a circuit without a ground.

I removed the GFI from my 120v charger. And ran a full charge cycle with it (35 hours :-( No problems.

Note: I did not stand in a puddle while handling the cord. I did not stick my fingers in the socket. I did not chew on the cord while it was charging. YMMV

The ACP Reductive charging may introduce some leakage and perhaps could trip a more touchy GFCI.

Thoughts on EV Charging Interfaces

...At the beginning I assumed that any electric vehicle would use a switching power supply as its charger. This is not necessarily the case. It's an interesting coincidence that the EV1's battery pack voltage, 312 volts, is not much below that produced by direct rectification of the 240 VAC power line (340 volts). Given that the EV1's inverter (the electronic circuit that converts DC into AC for the induction motor) looks very much like a DC switching power supply in reverse, it's possible to feed 240V AC line current directly back into the inverter. This would use the inverter as if it were doing regenerative braking -- with the AC power line taking the place of the motor/generator. This approach, called reductive charging by Alan Cocconi (one of the original EV1 designers) has the advantage of requiring neither an offboard charger like the Magnecharger or the nearly equivalent onboard charger. The inverter would double as the charger, and with its existing liquid cooling system it could probably handle some fairly high charging power levels -- at least as high as those encountered in highway cruising.
This approach would dictate a conductive interface.
For safety's sake, this approach would require the complete isolation of the propulsion battery and all related circuitry from the chassis of the car. Both the negative and positive lines from the propulsion battery would be "hot" with AC with respect to ground while charging. The EV1 is already designed this way. But Cocconi reports that even with this isolation, small leakage currents can exist that will trip a GFCI in the supply circuit and careful design of the drive motor is required to eliminate them.
As an alternative, a stationary AC isolation transformer could be provided on the outlet used for charging. But because this would have to be a 60 Hz transformer rated for full charging power, it would be physically large and heavy. It could easily be heavier and possibly even more expensive than the existing Magnecharger.
The existing switch-mode chargers, for all their faults, do provide AC ground isolation "for free" through their high-frequency transformers -- either the one built into the car (conductive approach) or the one formed by the paddle and coupler in the inductive approach. And they do adapt readily to changes in AC line voltages. Both problems would have to be solved in any direct AC charging scheme...

EV digest 5003

...
it is a consequence of using a high-frequency switcher for your
charger and/or controller.

Every wire in your EV's high voltage propulsion system has capacitance to
ground. Large conductors, laying right against the metal body, for long
distances, all conspire to create relatively large capacitances.

If you use a plain old 60 Hz transformer-based charger, and a plain old
contactor controller, the AC current in all these capacitors is low enough to
ignore. It won't reach 5ma, and won't trip a GFCI, and won't represent a
shock hazard if, for example, the ground wire breaks while you are charging
and someone touches the car body and actual earth ground.

If you have a high-frequency switcher for a charger, then this same stray
capacitance can carry a substantially higher current. Now you *can* get over
5ma, trip the GFCI, or get a shock...

[EVDL] camping at the charging station - DIY Electric Car Forums

...In my RV (and concession stand) I carry an "electrical survival kit" that
enables me to bypass GFIs when there is no other option. Such as staying at a
friend's house for a couple of days. There is a "reverse jesus" cord that
consists of a female 30 amp outlet, a short length of SO cord and heavy gator
clips. I simply pop the cover off the GFI outlet, optionally loosen the
mounting screws a little and tap onto the incoming terminals. Viola! Instant
bypass. I have been known to move the wires from the "LINE" side to the
"LOAD" side of the GFI which makes it still appear to work but it doesn't cut
off the juice...

 

[TEG]

GFCI as seen on the plug of a Tesla MC120 charge cable:

 

[TEG]

GFCI as it relates to 240V EV charging discussion here:

...
[FONT=Verdana, sans-serif, Helvetica]GFCI's
represent remarkable technology and their broad scale use has
contributed significantly to dramatic improvements in electrical
safety. There are presently two embodiments of this technology - GFCI
duplex receptacles and GFCI circuit breakers - in common use. There
are two important design considerations in this technology that must
be understood

First, the product must work with both pre- and post-1962
construction, double insulated(ungrounded) appliances, and older
utilization equipment. In 1962, the NEC introduced Article 250
requiring grounding in all new construction and modifications to
existing construction. The installation of the grounding electrode and
protective earth represents the most significant advance in electrical
safety this century and brought the U.S and Canada in harmony with all
the other electrical networks in the world. A GFCI device must protect
all consumers and has been designed to protect against shock hazards
for both grounded(post 1962) and ungrounded(pre-1962) installations
and both grounded and ungrounded appliances - thus the trip level is 5
mA +/- 1 mA.

GFCI receptacles are successfully used with small appliances in the
home particularly in damp or wet locations. Their use with large
appliances is less frequent for an important reason. The American
National Standards Institute has published a standard ANSI C101-1992
titled "American National Standard for Leakage Current for Appliances"
that applies to all electrical appliances. This standard limits the
"allowable leakage currents" in all electrical appliances to 0.5 mA or
1/10th the nominal trip level of GFCI's. This limit is established by
the physiological effect of electric current called perception. The
logic is quite clear - a consumer should not be able to feel or
perceive any electrical current when touching an appliance. For small
common household appliances operating at 120 volts, this requirement
can be easily achieved. As the appliance grows in size, the potential
leakage paths increase in number and size, or FCC compliance requires
capacitive filtering, it becomes more difficult. Thus, GFCI's for
larger appliances is not as prevalent.

For electric vehicles the task of controlling allowable current
leakage becomes technically challenging. Controlling and maintaining
leakage currents with a 75 hp motor, 25 kWh battery, 100 kW drive
inverter, 6 kW charger, 2 kW DC-DC converter, and the entire
electrical system of an automobile that has been driving over all
kinds of roads in all kinds of weather conditions is insurmountable.

This is the same problem for RV's. RV parks do not use GFCI circuit
breakers as disconnects on NEMA14-50 equipment because the leakage
from multiple appliances would be additive and the GFCl detection
circuit would exhibit frequent and bothersome tripping. The solution
to this problem is in the traditional design requirements for the
common GFCI receptacle that it must operate effectively with
ungrounded home systems and ungrounded appliances

A landmark study by UL and funded by EPRI, Ford, GM, and Chrysler
established new requirements for ground fault protection suitable for
use with EV's and larger appliances. If it can be established that a
"reliable ground path" is available, the leakage levels and trip
points can be raised. This new family of GFCl's, called CClD2O
or Charge Current Interrupting Device - 20 mA, is the foundation of
the new requirement in the 1999 NEC for a listed Personnel Protection
System. This is the same basic technology that is used in the common
GFCI duplex receptacle and should be available at a similar price.
Furthermore, the CCID2O must be used with a Ground Monitor/
Interrupter(GM/I) which achieves the same objectives of precluding the
consumer, or EV user, from feeling any electrical current when
touching the vehicle. A GM/I device is very simple low cost approach
to providing the same level of safety for EVs and large appliances
that consumers are provided by normal ANSI C1Ol compliant appliances
and standard GFCl receptacles. Monitoring correct circuit wiring,
including the ground presence, is the same technology found in circuit
testers available in hardware stores for a few dollars.

A comparison of the typical usage for the GFCI receptacle, GFCI
circuit breaker, and CClD2O follows:

The GFCI duplex receptacle, which requires monthly testing by the
user, is specified for use in damp/wet locations to serve a one or two
ANSI Cl01 compliant appliances. Under these conditions, perception is
avoided and tetanization is precluded whether the supply or appliance
is grounded or ungrounded.

The GFCI circuit breaker, which requires monthly testing by the user,
is normally specified for use with a large single appliance, such as a
hot tub. It is not normally used to provide protection on circuits
serving multiple appliances, such as RVs, because cumulative allowable
leakage levels can lead to frequent and bothersome nuisance tripping
when no actual hazard exists. This product provides similar protection
as the GFCI receptacle when the connected appliance is in compliance
with ANSI ClOl

The CCID2O and GM/I, which automatic performs a self test prior each
time prior to "turning" on, was developed to provide equivalent
protection as the GFCI receptacle and circuit breaker for large
utilization equipment, such as EVs and RVs, where leakage current may
exceed ANSI ClOl levels. By assuring a low impedance path for leakage
currents, potential user current levels are effectively controlled at
or below the perception level and the objectives of ANSI ClOl are
achieved. Loss of ground and/or excessive leakage levels result in
safe interruption or "tripping".
...

[/FONT]

 

[TEG]

It seems one reason why some think a GFCI is required is because of NEC 625-22:

625-22. Personnel Protection System. The electric vehicle supply equipment shall have a listed system of protection against electric shock of personnel. The personnel protection system shall be composed of listed personnel protection devices and constructional features. Where cord- and plug- connected electric vehicle supply equipment is used, the interrupting device of a listed personnel protection system shall be provided and shall be an integral part of the attachment plug or shall be located in the power supply cable not more than 12 in. (305 mm) from the attachment plug.

About the NEC

NEC 625 isn't followed everywhere, so including GFCI may be just to satisfy certain locations / jurisdictions.

Apparently the mobile charge kit Martin made for himself doesn't include GFCI.

Is it time to revise the NEC based on what has been happening to Tesla with their GFCI problems?

 

[TEG]

From PG&E EV CHARGING ESSENTIALS:

The National Electrical Code (NEC)
The National Fire Protection Association’s National Electrical Code (NEC) sets standards for electrical construction and operation. The NFPA revises and publishes a new National Electrical Code Handbook every three years. The 1999 NEC update covers EV charger installation issues in Chapter 6, Article 625.
The 1999 NEC update has added new language to two sections of Article 625. Article 625-22 calls for personnel protection systems for EV charging systems to replace ground-fault current interrupter devices to protect from shock.

So that sounds like the NEC was already revised to say you could use something else (but what?) instead of GFCI.

 

[TEG]

Las Vegas Electric Vehicle Association - May 2009 Newsletter

...California Building Code, Section 1202:​

Non-commercial chargers require either a dedicated 40A-240V ground-fault circuit interrupter (GFCI) for a 3-to-8 hour charge; or a 15A-120V GFCI for a 10-15 hour charge.​

...

http://www.electricity-tool.com/doc/36373-ES8/

GREEN BUILDING DESIGN & CONSTRUCTION GUIDELINES / APRIL 1999 ELECTRICAL SYSTEMS
...New California Electric Code and California Building Code sections govern EV charging station installation. Non-commercial chargers require either a dedicated 40A-240V ground-fault circuit interrupter (GFCI) circuit for a 3-to 8-hour charge; or a 15A-120V GFCI circuit for a 10- to 15- hour charge. (120V charging stations are far less convenient for users because of the long charge time.)...

​

 

[TEG]

California Uniform Building Code As It Relates to Electric Vehicles

...625-9 Electric Vehicle Connectors...
(d) An electric vehicle supply connector shall be provided with a grounding pole that shall be the first to make and the last to break contact with the mating inlet.

Exception: Electric vehicle connectors protected by an isolated system or its equivalent in accordance with Article 250.
...
625-22. Ground-Fault Protection for Personnel. The electric vehicle supply equipment shall have an approved system of protection against electric shock of personnel. When a current to ground exceeds some predetermined value that is less than the current required to operate the overcurrent protective device of the supply circuit, the system shall de-energize the electric vehicle supply equipment within an established period of time. Where cord- and plug-connected electric vehicle supply equipment is used, the ground-fault interrupter protection for personnel shall be an integral part of the attachment plug or shall be located in the power supply cable not more than 12 inches (305mm) from the attachment plug.

 

[Tdave]

What's this talk of a required 40A-240V GFCI? Does such a beast exist? Word from Tesla as to why the 240V connector is only 30A right now is because there is no 40A-240V GFCI on the market for them to incorporate into it.

 

[TEG]

Heavy Duty 40A - GFCI | Technology Research Corporation

Heavy Duty - High Power GFCI - 240V/40A

1-GF-50AHC GFCI - Spa Parts Shop

Electrical Forum - Seeking Advice - GFCI breaker constantly tripping

http://www.schneider-electric.us/?LinkServID=3F969ADB-215E-545B-E0E7146E68423F1D&showMeta=0

GFCI, 50A, High Current, 240V | 6895-BLK | Cheap Pool Products

GFCI, 50A, High Current, 240V

 

[TEG]

EVDL Archive / Forum Interface - Electric Vehicle Discussion List

...A GFCI will reduce the risk, by limiting the current to 5 ma or less (a nasty shock, but not likely to be fatal). But beginners are inclined to leave it out, or bypass it because it trips when it rains or the humidity is high.

An isolated charger (or isolation transformer added to a non-isolated charger) blocks the leakage path from AC line to earth ground. This eliminates charging-related shock hazards; but you can still get shocks from touching two battery terminals, of course....

Re: Charging safety, was: Dumb to smart charger converter by Lee Hart Aug 10, 2008; 09:45am

Barry Oppenheim wrote:
> Lee. So are you suggesting that when charging the car, using a
> non-isolated charger, it should be grounded to a GFI outlet? If so,
> what is the easiest way to implement that?
>
> If not, what would you consider "best practice" for using a
> non-isolated charger (i.e. PFC20/30/50)?
>
> Could you skip grounding the vehicle and using a GFI if you used an
> enclosed battery box constructed of fiberglass or polypropylene?

There are two commonly accepted practices.

First, you can ground the chassis of the vehicle via the third (green) wire in the cord. Use a GFCI, which checks to make sure that all the current going out one AC hot wire (black) is coming back on the other wire (white). If it is off by more than 5ma, the GFCI trips. If there is any leakage current (less than that 5 ma), it is very likely to be flowing between hot and chassis ground (for example, through the wet tops of the batteries to the vehicle's chassis), and not between hot and a person to earth ground (for example, through a person touching a battery terminal and standing barefoot in a mud puddle).

(Note that the car companies, in their infinite wisdom, decided that 5 ma is too tight a standard; so they used 20 ma for their EVs produced for the CA ZEV mandate. They felt that 20 ma is safe enough, because most people won't die from it under most circumstances.)

Second, you can use the "double insulation" technique. You find this in various consumer products that do not have a cord with a third ground wire. For this to work, the entire electrical system of the car has to be totally insulated from all exposed metal surfaces. This means that the batteries, controller, motor, wiring, and all related part are in insulated boxes or enclosures. For safety, there needs to be two completely independent redundant insulation systems, each able to withstand the full peak voltage that might be impressed across it, including any environmental conditions (water, dirt, road salt, rodents, etc). The safety agencies also want electrical grade insulating materials to be used, that won't melt, burn, decompose, or carbonize to
become conductive.

This is a very difficult standard to meet. To my knowledge, it has mainly been used in very small EVs like electric bikes or scooters, thoughAC Propulsion has done it in some of their EV prototypes.

On best practices for a non-isolated charger: At the very least, a non-isolated charger has to be used with a GFCI. For me, I would add my own isolation transformer.

...You generally don't want two GFCI in series. Sometimes this can make them trip falsely...

 

[TEG]

EVDL Archive / Forum Interface - Electric Vehicle Discussion List

...You generally don't want two GFCI in series. Sometimes this can make them trip falsely...

Perhaps that is why some customers are/were having GFCI trip problems? It looks like Stephano's Milbank panel install to Tesla charger is using double (in series) GFCIs on the 120V:

(note the test buttons both on the Tesla cord, and on the small GFCI breaker above it)

 

[vfx]

Perhaps that is why some customers are/were having GFCI trip problems? It looks like
(note the test buttons both on the Tesla cord, and on the small GFCI breaker above it)

I told SP about the double GFI Roadster trip problem when Doug posted the info on his Milbank installs. About that time Tesla announced the "fix".

 

[TEG]

Did the fix work?

 

[vfx]

Did the fix work?

Apparently not all who have had the firmware upgrade have had a resolution. Many have replaced the GFCI plug on the MC120 with a standard plug. Don't know if the MC240 has any GFCI issues.

 

[vfx]

In the home GCFIs are required outdoors and in rooms like kitchen and bath. I was told yesterday that bedrooms are next (very soon) and you might as well just do the whole house if you are building new.

Could this be another tiny time bomb issue for charging future EVs?

 

[TEG]

I don't know if this info is correct, but here is a site that claims "experts" say that two GFCIs are more dangerous than one:
2007 HOT SPRINGS SAFETY SEMINAR - Tips from industry experts

Breakers and fuses protect equipment, GFCI's protect you! Never connect two GFCIs together on the same power cord. All it takes to kill a person is 50 miliamps and a GFCI is set to trip at 30 miliamps. If you connect two together it will ramp up to 60 mili amps before they trip, potentially killing anyone receiving the jolt.

Questioning the accuracy of the above... For one, I think many GFCIs are 5ma, not 30ma. For another, I am not sure I believe that two in series doubles the ma rating before trip. I would think it would be the lower of the two, but supposedly the above site was advice from an expert.

---
I spoke with someone who was frustrated that the MC120 had a GFCI because they said that the code required that the outdoor outlet, not the plug have the GFCI so there would be many cases where the outlet already had GFCI. Perhaps there should be two versions of the MC120 - the existing one for indoor / garage use where there is no GFCI on the socket, and another for outdoor use (which doesn't include a GFCI) that expects the outlet to already have the GFCI?

Apparently the firmware change ramps up the current draw more slowly to avoid tripping one (or more) GFCIs in the circuit.

 

[vfx]

Perhaps there should be two versions of the MC120 - the existing one for indoor / garage use where there is no GFCI on the socket, and another for outdoor use (which doesn't include a GFCI) that expects the outlet to already have the GFCI?

What if they only made the non GFCI and included one of these:
Prime Wire & Cable Portable GFCI Adapter and Surge Protector, Model# GFP10000 | Switches + Fuses | Northern Tool + Equipment

http://www.tycothermal.com/assets/A...ent/Datasheets/1632/H55402_H931_DS_032006.pdf

Tower Shock Buster Portable GFCI

 

[TEG]

Yep, that might of worked... I guess they didn't want to take the risk that someone would forget to install the add-on GFCI when there wasn't already one behind the socket.

By the way, more GFCI fun:
Two GFCIs in series - OK or not? [Archive] - Straight Dope Message Board

The code allows for multiple GFCI outlets in one line, although generally you only need to have the first in line protected.

Here's something I found out the hard way. A ground fault circuit interrupter works by measuring the current flow in the hot leg, and comparing it to the current in the neutral leg, and if it detects that the currents don't match, it assumes the extra current has "gone to ground" and trips the breaker.
If you are not grounded, and grab both legs so that current can flow from one leg to the other through your body, the GFCI doesn't mind this a bit. It was the late seventies, and GFCI were fairly new, and I didn't know how they worked, and tested one this way. It was only 110V, but it kind of caught me by surprise. I have to admit, there were beverages involved.

Part of the process is to bleed a tiny bit of current into the ground wire if I remember correctly. If you have too many GFIs in the circuit, the sum of al those tiny losses might trip the protection.
And it doesn't do any good to have more than one. Once one opens the circuit is dead and the others won't see any current to be unbalanced.
This is not correct.
A GFCI doesn't even need the "third prong" connected to earth ground in order to work. If you want proof of this, consider that the NEC allows 2-prong, ungrounded receptacles to be replaced with 3-prong, GFCI receptacles (assuming it is properly labeled).

I don't know what the NEC says about GFCIs in series, but my younger brother, a Master Electrician, advises against it. According to him, series GFCIs can lead to undesirable effects including nuisance trips (I have seen this myself) or failure to trip properly (I have not seen this nor pretend to understand how it could occur).

Here's an example of how a "shared neutral" might happen:

Let's say a bunch of receptacles, lights, and whatnot are connected to the load side of the GFCI. We say these things are "downstream" from the GFCI, and thus they are all GFCI-protected. Afterwards, someone decides to install a ceiling light. They connect the ceiling light's "hot" to a circuit that is not GFCI protected (or they run the ceiling light's "hot" wire directly back to a circuit breaker in the panel). They connect the ceiling light's "neutral" wire to a neutral that is downstream from the GFCI. This creates an automatic imbalance on the downstream side of the GFCI when the ceiling light is used, and the GFCI will trip.

Here's an example of how a "shared hot" might happen:

Let's say a bunch of receptacles, lights, and whatnot are connected to the load side of the GFCI. We say these things are "downstream" from the GFCI, and they are all GFCI-protected. Afterwards, someone decides to install a ceiling light. They connect the ceiling light's "hot" to a circuit that is downstream from a GFCI. They connect the ceiling light's "neutral" wire to a circuit that is not GFCI-protected (or they run the ceiling light's "neutral" wire directly back to the CB panel). This creates an automatic imbalance on the downstream side of the GFCI when the ceiling light is used, and the GFCI will trip.

Additionally, GFCIs don't like poor connections in downstream circuits. Granted, it shouldn't make a difference, but when I installed GFCIs in my late 70's home to upgrade electrical compliance, nuisance tripping was common. Only after I opened each device box, removed backstab connections and remade them to the screw terminals did the tripping stop. I can't explain it, but making good connections on the downstream receptacles alleviated the problem.

Your main problem is likely to be discrimination.

We in the UK call these things Residual Current Devices(RCDs), they work particularly well for us because our entire system is neutral grounded using a 3 wire system.

The problem with multiple RCDs is that they not only will have a tripping current, they also have tripping times, so that a surge will not cause unwanted interrupts.

Ideally you put RCDs with longer trip times further toward the incoming supply connection, so that those further down the line trip first.

Your problem comes when you install units with ostensibly the same tripping time, because the reality is that there will always be some small differance.
This can then lead to unwanted upstream tripping, and leave the downstream device still on and can then lead to problems working out which is the faulty circuit.

This is where you pay for a person who knows what to look for in manufacturers specifications instead of doing the job yourself.

This can happen with fuses as well, but fuses tend not to be used in the same way so the safety issues are differant.

 

[W.Petefish]

Has anyone, other than me, had their HPC's GFCI trip?

 

[bonnie]

What if they only made the non GFCI and included one of these:
Prime Wire & Cable Portable GFCI Adapter and Surge Protector, Model# GFP10000 | Switches + Fuses | Northern Tool + Equipment

http://www.tycothermal.com/assets/A...ent/Datasheets/1632/H55402_H931_DS_032006.pdf

Tower Shock Buster Portable GFCI

I bought one of those and threw it in my bag when I removed the GFCI from my cable assembly. Had Tesla done that to begin with, it would have saved me from much charging frustration on a roadtrip.