charging on generator

[hill]

I used just ONE .5 watt 100k ohm resistor inside the NEMA L15-30P. I wanted to see if that would work. It's reduced down to a measly 5-15R receptacle - and about a 4" run of #10 wire - charging at 240v for greater efficiency . . . and no . . . it hasn't ever gotten warm ... yet

.

 

[wwhitney]

Basically, if you have no solid ground reference, you should not bond anything. If you are willing to drive an 8 foot copper ground rod, then a hard bond is ok.

A ground rod might give you a couple hundred ohm connection to earth. I don't see how this can enhance the personnel safety of the installation. It certainly isn't going to pass enough current to trip a circuit breaker, and reading the Honda EU2000i manual didn't indicate any GFCI protection on the generator receptacles. What am I missing?

Thanks,
Wayne

 

[Ingineer]

Basically, if you have no solid ground reference, you should not bond anything. If you are willing to drive an 8 foot copper ground rod, then a hard bond is ok.

A ground rod might give you a couple hundred ohm connection to earth. I don't see how this can enhance the personnel safety of the installation. It certainly isn't going to pass enough current to trip a circuit breaker, and reading the Honda EU2000i manual didn't indicate any GFCI protection on the generator receptacles. What am I missing?

Thanks,
Wayne

The goal of the ground rod is not to pass enough current to trip a breaker, it's to ensure that conductive appliances, such as the body of the Leaf, at at the SAME potential as earth. Imagine a child standing barefoot in wet grass, touching your Leaf, which could, without an earth-referenced ground, pass lethal current, and also, the EVSE's GFCI will not detect it if the fault is caused by some other device, such as a simple extension cord end, dropped in a puddle or mud. (The Leaf would be the return through the body, and through the hard bond.)

Having a hard-bonded ground w/o a fixed reference (ground rod) could allow lethal current to pass back though to the Leaf body in the event of a low or medium resistance fault to earth.

So the 100k resistance will ensure there is no possibility of lethal current passage, while still allowing for static and RFI drain.

-Phil

 

[wwhitney]

Imagine a child standing barefoot in wet grass, touching your Leaf, which could, without an earth-referenced ground, pass lethal current.

So if your generator is floating and you have a hard bond from "neutral" to EGC, which is bonded to the car chassis though the EVSE, the child touching the car doesn't complete a circuit, as none of the circuit conductors are earthed.

Having a hard-bonded ground w/o a fixed reference (ground rod) could allow lethal current to pass back though to the Leaf body in the event of a low or medium resistance fault to earth.

If there is no earthing, it would take two faults to earth to complete a circuit.

The point of my comments is that my understanding of low voltage AC (120V-480V) electrical safety is that it depends on the bonding of the non-current carrying metallic components of the system, so that a fault from a circuit conductor to one of these parts will carry enough current to trip a circuit breaker, and that it doesn't depend on the earthing of that bonded system. The benefit of the earthing is possibly in reducing damage due to lightning and possibly in reducing the risk of static discharge due to the floating voltages of an unearthed system.

Cheers, Wayne

 

[Ingineer]

So if your generator is floating and you have a hard bond from "neutral" to EGC, which is bonded to the car chassis though the EVSE, the child touching the car doesn't complete a circuit, as none of the circuit conductors are earthed.

You are changing your scenario. My point was bonding Neutral to ground WITHOUT a ground reference could be dangerous, and this is why resistors should be used. You, for whatever reason, want to argue with me over a few cent resistor, are trying to say a bond without a ground reference is still safe, which I have proven is not with a valid scenario.

If there is no earthing, it would take two faults to earth to complete a circuit.

WRONG! It only takes one with your hard bond from neutral to the Leaf's body. All it takes is hot in a puddle of water.

The point of my comments is that my understanding of low voltage AC (120V-480V) electrical safety is that it depends on the bonding of the non-current carrying metallic components of the system, so that a fault from a circuit conductor to one of these parts will carry enough current to trip a circuit breaker, and that it doesn't depend on the earthing of that bonded system. The benefit of the earthing is possibly in reducing damage due to lightning and possibly in reducing the risk of static discharge due to the floating voltages of an unearthed system.

My point is that an unbonded system is safer if you could have the non-current carrying metallic components backfire and be used to send dangerous voltage into a person. On a truly floating system, you would need 2 faults to have current flow, and since the Leaf is protected by the EVSE's GFCI, the danger would be from external current flowing through the bond. You do not need 2 faults with a bond to "neutral", only a path from "hot" to the actual earth which is possible with a generator and one extension cord end dropped in a puddle.

If you want to argue further, fine. I am done. I recommend all people use high-resistance bonds for safety. If you want to ignore my advice over a few cents worth of resistors, and someone gets hurt, that's your prerogative.

-Phil

 

[wwhitney]

You, for whatever reason, want to argue with me over a few cent resistor, are trying to say a bond without a ground reference is still safe, which I have proven is not with a valid scenario.

First, let me just say that you misunderstand my motives and I don't care about a few cents of resistors or wish to argue. I am interested in understanding the electrical theory here. Earthing and bonding are a perennial source of confusion for many people.

It seems that I have misunderstood your brief description of this car/child/extension cord scenario. [Indeed on first reading I thought you were talking about two different scenarios]. I will reflect upon your further comments and respond subsequently. I hope you will give my comments consideration in the spirit of intellectual discourse.

Yours,
Wayne

 

[wwhitney]

Imagine a child standing barefoot in wet grass, touching your Leaf, which could, without an earth-referenced ground, pass lethal current, and also, the EVSE's GFCI will not detect it if the fault is caused by some other device, such as a simple extension cord end, dropped in a puddle or mud.

OK, I see now you mean all this happening at once. To be more explicit: a 120V generator with three receptacles, one has the EVSE going to the car, one has the "neutral"-EGC low resistance grounding plug, and one has an extension cord whose other end I carelessly throw into a puddle of water.

For simplicity, say only the "hot" wipers are in the water, so the earth gets energized but there is no return path to the generator. That is, until I come along and stand in the wet grass and touch the car. Then my body completes the circuit via the "neutral"-EGC bond and I get a shock. If the "hot" - earth connection and the connection through my body are both 1000 ohms, then I get 60 ma through my body and that could be lethal.

Back to my original question, does adding a ground rod to this scenario make it safe? The ground rod presents another return path from earth of lower resistance than the path through my body. Say the ground rod has a resistance of 100 ohms. Then the total current through the extension cord increases to 110 ma, but the current through my body reduces to 10 ma. So I still get a shock, but it shouldn't be dangerous.

However, this is very sensitive to the actual resistances involved. If the ground rod resistance is 300 ohms, the puddle resistance is 300 ohms, and my body resistance stays 1000 ohms, then the current through the extension cord is over 200 ma, and the current through my body is up to 50 ma, which is dangerous or possiblely lethal.

So as far as I can see, while a ground rod makes this installation safer, it doesn't remove the risk in this scenario.

Cheers, Wayne

 

[Ingineer]

My point is not that a ground rod is safer, (which it is) because nobody is going to bother driving an 8 foot ground rod for a portable generator anyway. It's the hard bond of Neutral to ground which I am opposing. I stand by my recommendation of two 100k resistors so ground is electrically floating "in the middle" at +/- 60v.

-Phil

 

[KJD]

My point is not that a ground rod is safer, (which it is) because nobody is going to bother driving an 8 foot ground rod for a portable generator anyway. It's the hard bond of Neutral to ground which I am opposing. I stand by my recommendation of two 100k resistors so ground is electrically floating "in the middle" at +/- 60v.

-Phil

The problem I see here is Hill used only one resistor instead of doing as Phil said and using 2 resistors.

 

[wwhitney]

My point is not that a ground rod is safer

Oh, that was the issue I was commenting on, sorry if you thought I was commenting on the issue of solid bonding versus resistance bonding.

BTW, since this comes up because the Panasonic EVSE does an EGC continuity check, does it perform that check continuously or just at bootup? If the latter, one could remove the bonding plug after charging starts if desired.

It's the hard bond of Neutral to ground which I am opposing.

Yes, there definitely is a strong argument that a hard bond from neutral to EGC on a portable generator (with or without ground rod) increases the overall shock risk. However, such a bond is required in many places, such as on an OSHA jobsite. And with a grounding electrode installed, it is no more or less dangerous than the usual household electrical system. Your example of the EVSE, the car, and the extension cord in a puddle can occur with household wiring, too.

Cheers, Wayne

 

[smkettner]

BTW, since this comes up because the Panasonic EVSE does an EGC continuity check, does it perform that check continuously or just at bootup? If the latter, one could remove the bonding plug after charging starts if desired.

My V1 upgraded Panasonic EVSE when charging on 120v generator and dual resistor bonding plug stopped charging when the plug was removed. Restarted when plug was reinserted.

 

[RegGuheert]

I used just ONE .5 watt 100k ohm resistor inside the NEMA L15-30P. I wanted to see if that would work. It's reduced down to a measly 5-15R receptacle - and about a 4" run of #10 wire - charging at 240v for greater efficiency . . . and no . . . it hasn't ever gotten warm ... yet

I have the same generator and I accomplished the same goal with a single resistor between neutral and ground in a DUMMY 5-15P. The only thing in the 5-15P is the 100Kohm resistor and I plug it into one of the 120V plugs on the generator. Then I plug the EVSEUpgrade directly into the 240V using a 3-wire to 4-wire adapter, both twist locks. There is no need to run 240V (or 13A) through a 120V connector.

Thanks to Phil for the tip here! Works great!

 

[gabeyd]

Is this something that I should do with my generator anyway? Would it make it safer for use to my RV? My generator owner's manual actually recommends driving a grounding rod, and has a connection point on the generator, but of course, no one does that, myself included. I have a Yamaha EF2400is, my trailer is 30A 120V plug, but of course it isn't getting 30A from that generator, and I'm plugging it in with a 30A to 15A pig tail.

If I'm powering my RV from my generator, would it be safer to do two 100kOhm resisters in that case too? Or does the trailer charge / power system likely already have such a setup? (I've never checked the resistance between prongs on the trailer, but I could...).

 

[carphen]

I am sure my Xantrex Prosine 1800 would easily drive the L1 charging. Not sure if there is a neutral ground bond when inverting to get through the brick.

I need to give it a go and see what happens.

I'm finding the EVSE's very fussy about grounding.... running a 50Hz 240V (British) Leaf on a powerstar full sine wave (split phase) inverter OK, but when I got a (new, converted) EVSE from California (so I can plug in to the local 110V 50Hz grid) it finds the ground on the inverter missing when connected to 110V. This when it's happy with a Trace modified sine wave next door with the same ground (even bonded together). Sadly, with the Trace, the charging switches off and restarts about every 30 seconds... doesn't like the square wave I guess.

Anyone has a way of reliably fooling the EVSE?... its not that my ground is bad (just added 6 (rather short) ground rods all bonded together)

 

[Ingineer]

I'm finding the EVSE's very fussy about grounding.... running a 50Hz 240V (British) Leaf on a powerstar full sine wave (split phase) inverter OK, but when I got a (new, converted) EVSE from California (so I can plug in to the local 110V 50Hz grid) it finds the ground on the inverter missing when connected to 110V.

We can disable the ground verification feature on any of our upgraded units.

Anyone has a way of reliably fooling the EVSE?... its not that my ground is bad (just added 6 (rather short) ground rods all bonded together)

I've already outlined how to do this on page 4 of this thread:

The easy way to make this work is take a screw-on plug (NEMA 5-15P) and install two 1/2 watt 100k ohm resistors. One from neutral (silver screw) to ground (green), and the other from hot (gold screw) to ground (green). Then simply plug this into one outlet on the generator, and your EVSE into the other. This will safely pass the ground detect on the Nissan (and our upgraded) EVSE, while not being a hazard in any other way.

This trick will work on inverters as well as generators.

-Phil

 

[carphen]

I didn't know.... but will try the resistor setup.... thanks. When there are NO charging stations, one needs to be sure to take whatever will work to wherever you will need to charge! Thanks again

 

[hill]

The easy way to make this work is take a screw-on plug (NEMA 5-15P) and install two 1/2 watt 100k ohm resistors. One from neutral (silver screw) to ground (green), and the other from hot (gold screw) to ground (green). Then simply plug this into one outlet on the generator, and your EVSE into the other. This will safely pass the ground detect on the Nissan (and our upgraded) EVSE, while not being a hazard in any other way.

Hey Phil, just thought of something. If charging from a 240 volt generator would it be beneficial to connect both hot legs and the neutral to ground via the resistors?

Yes, this is 100% correct. Then earth is then properly floating is in the "middle". This is also how we advise our European customers who have isolated grounds. (some places in Europe do)

-Phil

(sigh) The above quote/photo raised my eyebrow for 2 reasons;
1) Photo shows 3 prong plug ... but references, "2 hots, neutral and ground" ... where's the neutral prong ?!?
2) Resistors between 2 hots AND neutral to ground ... wouldn't that require 3 resistors?

Sorry for the revisit. Months ago I spoofed our Leaf's portable EVSE using a single 1/2w 100k ohm resistor between our 240V Honda generator's Neutral and Ground. So am I to understand now, that resistor'ing the 2 hots also - is even safer - "more beneficial" on a 240v generator?

 

[Ingineer]

(sigh) The above quote/photo raised my eyebrow for 2 reasons;
1) Photo shows 3 prong plug ... but references, "2 hots, neutral and ground" ... where's the neutral prong ?!?
2) Resistors between 2 hots AND neutral to ground ... wouldn't that require 3 resistors?

Sorry for the revisit. Months ago I spoofed our Leaf's portable EVSE using a single 1/2w 100k ohm resistor between our 240V Honda generator's Neutral and Ground. So am I to understand now, that resistor'ing the 2 hots also - is even safer - "more beneficial" on a 240v generator?

This is a european plug, it has "Earth", "Line", and "Neutral". (Ground, Hot, Neutral)

There is never a 4 wire configuration on our EVSE's. It's either 2 hots and a ground (240v US) or Hot, Neutral, Ground (120v US or 240V EU). Either way, I recommend two 100k 1/2w resistors in a "Y" configuration from Ground/Earth.

-Phil

 

[hill]

Thanks I'm officially clarified. I can't do the rewire right now or I would. It seems a good part of Lake Forest and Irvine are experiencing a power outage .... so the Honda generator is a little busy right now.

 

[jpokoraw1]

Would this work to link two generators together to build a 240v outlet? http://www.quick220.com/" onclick="window.open(this.href);return false;

I think the Honda eu2000i are non-GFI