Overcoming bonded neutral issues in the setting of a GFI protected Ford Lighting 7.4kw inverter.....

[Checkthisout]

I think this is the big hang up in this thread. There is a misconception about what is and isn't grounded if the green wire is not connected on one end. The answer is everything is still grounded. The truck is grounded by the N-G bond at the inverter. The house is grounded by the main bonding jumper in the panel. The cord is still grounded because the green wire is connected on one end or the other, just not both.

I can't imagine the neutral and ground which are bonded in the inverter, are also bonded to the chassis.

The lightning then also has a charging port. Are those a 2 or 3 wire conductor and is that ground even connected to the chassis?

There is a lot going on there. You have 240v incoming going to a charger, a voltage reducer for chassis voltage and then you have battery voltage and then an inverter for 120 volts.

Going to guess Primary battery Negative, Chassis Voltage Negative, Incoming power cord ground and output inverter ground neutral aren't all bonded and connected to the chassis.

So no, with the egc disconnected and some failure mode, you wouldn't get shocked if you touched the truck.

 

[Shimmy]

What are the additional safeties?

@crossy maybe you can help me here. What is different with an EV charger outside the US? I know ground fault/residual current detection, but I remember you posting a whole host of other protections on a different forum.

 

[Checkthisout]

Look at your description. You have two islands with neutral-ground bonds but a common neutral. Any current on the neutral will find its way back to the source in proportion to the path impedances (Kirchoff). So, barefoot on a wet garage floor and you will find yourself part of that path.

Why would you hook into the truck's power cord and not the outlet in the garage?

No pun intended but you're more likely to get struck by Lightning than you are to have the stars line up in any of these scenarios.

 

[zanydroid]

Why would you hook into the truck's power cord and not the outlet in the garage?

Why won’t this happen on a worksite where the truck is being used to power a temp power panel? What’s to stop the workers from plugging in on any outlet they want?

There are definitely some unsafe situations here esp if you multiply it out to thousands of worksites or workdays.

 

[CoolWill]

Look at your description. You have two islands with neutral-ground bonds but a common neutral. Any current on the neutral will find its way back to the source in proportion to the path impedances (Kirchoff). So, barefoot on a wet garage floor and you will find yourself part of that path.

How is that different from the utility service? The Ford is the utility transformer and the cord is the service drop.

 

[Shimmy]

How is that different from the utility service? The Ford is the utility transformer and the cord is the service drop.

You don't have two bonds within your home.

 

[Checkthisout]

Why won’t this happen on a worksite where the truck is being used to power a temp power panel? What’s to stop the workers from plugging in on any outlet they want?

There are definitely some unsafe situations here esp if you multiply it out to thousands of worksites or workdays.

You wouldn't give the workers your cord with the defeated EGC.

 

[Checkthisout]

How is that different from the utility service? The Ford is the utility transformer and the cord is the service drop.

They are asserting someone will defeat the egc in the cord and hook it up to their house.

Someone else will come along, unplug the cord from their house and use a 30 amp splitter with 20 amp outlets on it, plug the house back on somehow, Someone will then go get a power tool, here-said power tool will generate a hot to case short and because the house has a ground-rod, the electricity will travel through the person, through the ground back to the ground rod and complete the circuit with the truck and get shocked without tripping the GFCI.

 

[CoolWill]

You don't have two bonds within your home.

What does that mean? The neutral is bonded in the panel, creating the EGC for the house. The neutral is bonded at the truck, creating the EGC at the inverter. This is identical to the utility transformer except at 120 volts.

 

[CoolWill]

They are asserting someone will defeat the egc in the cord and hook it up to their house.

Someone else will come along, unplug the cord from their house and use a 30 amp splitter with 20 amp outlets on it, plug the house back on somehow, Someone will then go get a power tool, here-said power tool will generate a hot to case short and because the house has a ground-rod, the electricity will travel through the person, through the ground back to the ground rod and complete the circuit with the truck and get shocked without tripping the GFCI.

Oh well, yeah happens all the time. My neighbor recently ran a cord over with a lawn mower and then accidentally dropped the live end into a pile of thermite that burned through a propane tank. A whole orphanage and two buses of hurricane disaster relief workers were injured. The fire trucks and ambulances disrupted a mostly-peaceful BLM riot and we were all very upset.

 

[Hedges]

I can't imagine the neutral and ground which are bonded in the inverter, are also bonded to the chassis.

The lightning then also has a charging port. Are those a 2 or 3 wire conductor and is that ground even connected to the chassis?

I would expect the ground wire bonded to truck's chassis in both cases.

If charger brings line voltage AC to wiring inside the truck, a fault could electrify chassis and parasitic capacitance could as well.
Inverter output could fault to chassis. You don't want chassis a different voltage than a "grounded" metal power tool plugged into outlet.

 

[zanydroid]

They are asserting someone will defeat the egc in the cord and hook it up to their house.

Someone else will come along, unplug the cord from their house and use a 30 amp splitter with 20 amp outlets on it, plug the house back on somehow, Someone will then go get a power tool, here-said power tool will generate a hot to case short and because the house has a ground-rod, the electricity will travel through the person, through the ground back to the ground rod and complete the circuit with the truck and get shocked without tripping the GFCI.

Sigh. This thread is not worth participating in anymore, and I’m not super inclined to participate in further discussions with this attitude.

I’m explaining why in general this would not be allowed by NEC or OSHA rules. The probability of a problem if there are multiple people involved is actually far enough from zero.

The fault within a tool is definitely within the range of probability that they care about. Otherwise why would there be double insulation rules.

There’s no need to introduce the splitter to have an issue, since the truck bed receptacles do the necessary splitting. If the truckbed was augmented with another GFCI then there would be some safety clawed back from the extra ground leakage

 

[zanydroid]

How is that different from the utility service? The Ford is the utility transformer and the cord is the service drop.

It is analogous in a circuit sense due to bonds at both sides. However the physical accessibility of both ends is very different. Utility transformer has no outlet taps on it, is locked, and possibly buried or on a pole. The service is protected by a very robust wiring method, buried conduit or secured to a mast pretty high up. You are not able to climb inside the utility transformer , it’s not a thing you touch all the time.

One major electrical difference is utility transformer is grounded via a local rod after step down. The car is not re-grounded again in addition to its N-G bond

 

[Checkthisout]

I would expect the ground wire bonded to truck's chassis in both cases.

If charger brings line voltage AC to wiring inside the truck, a fault could electrify chassis and parasitic capacitance could as well.
Inverter output could fault to chassis. You don't want chassis a different voltage than a "grounded" metal power tool plugged into outlet.

Yeah I dunno. It would be interesting to see a schematic.

 

[Checkthisout]

I’m explaining why in general this would not be allowed by NEC or OSHA rules. The probability of a problem if there are multiple people involved is actually far enough from zero.

The fault within a tool is definitely within the range of probability that they care about. Otherwise why would there be double insulation rules.

There’s no need to introduce the splitter to have an issue, since the truck bed receptacles do the necessary splitting. If the truckbed was augmented with another GFCI then there would be some safety clawed back from the extra ground leakage

Ok. I thought we were discussing safety revolving around use when hooking it up to a household service. I thought we were already all in agreement that GFCI is a good thing and are not talking about defeating it when using it for jobsite power.

My bad.

 

[Hedges]

GFCI being available as a UL listed component, I would expect any system with one to have it as GFCI outlet, GFCI breaker, or GFCI in-line module.
To power portable devices from the truck you would want to plug into that.

To feed a house panel, with it's own G-N bond and ground rod, and GFCI for select circuits, would like something such as twist-loc outlet from before the GFCI on the lightning.
But you'd still have two N-G bonds. 3-pole transfer switch is my best suggestion.
This would also work with GFCI of Lightning in the path, but with that feeding all circuits of backup loads panel, may nuisance trip.

In the case of powering an RV from Lightning (likely application for people camping, except or the range anxiety), then N-G bond in Lightning is what you want. (would like an actual ground, such as shore power provides, but that's another story

 

[CoolWill]

I think we're all missing the biggest mistake of all here: Buying a Ford.

 

[Checkthisout]

I think we're all missing the biggest mistake of all here: Buying a Ford.

I wouldn't want do it with the lightning but how cool is it that your 30 AMP RV connection can be plugged into the Hybrid truck?

Huge battery and almost silent recharge capability. ?

 

[hammick]

Some clarification is certainly needed here. We are talking about the F150 Lighting Lariat (not the hybrid) with the "Pro Power" option. With that you get an LR14-30R 240v receptacle in the bed and 4 120v receptacles. All are protected with spring loaded waterproof covers. The truck knows when a cover is open and alerts you on the big screen if you want to turn it on. You can turn on the power at the bed with a water proof button or in the truck on the touch screen. Each 120v leg (L1 & L2) is protected by a waterproof push button GFCI breaker.

Each 120v leg puts out 3.6kw and there is a nice meter on the truck screen showing exactly how much load is on each leg. If you exceed 3.6kw the truck will shut off the power to both L1 & L2 and give you an overcurrent warning and the option to reset. If the truck detects a ground fault it will shut off power to L1 & L2 and give you a ground fault warning and the option to reset. You can also see the power being used on the Ford Pass app along with any overcurrent or ground faults. The LR14-30 has L1 L2 N & G.

Nobody is talking about tapping power from the Lightning at the charge port or at the high voltage battery cables. Just using the available 7.2kw of power at the bed outlets. You may have seen the commercials where Ford markets this.

I am not a electrician but I play one on TV and I see absolutely no difference between the Ford Pro Power and a 7000 watt gas generator with GFCI breakers. Well there is one difference. With the gas generator you can easily remove the ground to neutral bond. I suspect FORD could allow the bond to be broken via software but they never will for liability reasons.

 

[Checkthisout]

Some clarification is certainly needed here. We are talking about the F150 Lighting Lariat (not the hybrid) with the "Pro Power" option. With that you get an LR14-30R 240v receptacle in the bed and 4 120v receptacles. All are protected with spring loaded waterproof covers. The truck knows when a cover is open and alerts you on the big screen if you want to turn it on. You can turn on the power at the bed with a water proof button or in the truck on the touch screen. Each 120v leg (L1 & L2) is protected by a waterproof push button GFCI breaker.

Each 120v leg puts out 3.6kw and there is a nice meter on the truck screen showing exactly how much load is on each leg. If you exceed 3.6kw the truck will shut off the power to both L1 & L2 and give you an overcurrent warning and the option to reset. If the truck detects a ground fault it will shut off power to L1 & L2 and give you a ground fault warning and the option to reset. You can also see the power being used on the Ford Pass app along with any overcurrent or ground faults. The LR14-30 has L1 L2 N & G.

Nobody is talking about tapping power from the Lightning at the charge port or at the high voltage battery cables. Just using the available 7.2kw of power at the bed outlets. You may have seen the commercials where Ford markets this.

I am not a electrician but I play one on TV and I see absolutely no difference between the Ford Pro Power and a 7000 watt gas generator with GFCI breakers. Well there is one difference. With the gas generator you can easily remove the ground to neutral bond. I suspect FORD could allow the bond to be broken via software but they never will for liability reasons.


View attachment 168877

Is neutral bonded to the frame?