Whole home back up - a simple approach

[Yellow Buddy]

That's great to hear, John! The intelligent backup power system of the F-150 Lightning is most certainly awesome, and a feature we're proud to offer!

Uh….they’re not using the HiS. They’re using Pro Power in a way that is not code legal…you may want to contact your legal department and let them know you accidentally and publicly endorsed a non-code compliant method of using the truck…

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[Mmiketa]

Sorry, I get hung up doing three things at once sometimes, and my edits get garbled...my kids say I am 'long winded' also, lol.

The bottom line is you can use the 240V 30A outlet on the bed of the truck through a Transfer Switch that switches the neutrals. When you buy it, tell them you have a bonded generator so they provide the correct type of transfer switch.

Connect all 4 wires, hot, hot, neutral and ground from the truck outlet to the house generator inlet which leads to the transfer switch. You must use wiring rated to handle the 240V 30A continuous load which is what the truck will be providing. Premade wires can be had from generator stores that sell the transfer switches and generator inlets.

You also have to wire the transfer switch to the house service panel (main breaker panel). The instructions with the transfer switch explain how to wire it to the house service panel correctly so that the house panel is disconnected when the generator/Lightning is connected for power.

However, to wire the transfer switch you have to open your house service panel which has live wires from your utility inside, even when the main breaker is off, the service wires are hot. So there is a real risk of shock and death should you accidentally come into contact with them. So best to have a licensed electrician to wire the transfer switch to the panel.

If you want some info on the how and why, NEC code, etc., read on otherwise that's about it.
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The neutral is grounded at/bonded to the truck so you do not want the house neutral which is grounded at/bonded to the panel to be connected at the same time or else the GFCI will open erroneously.

Also, the transfer switch, must in this case transfer the neutral to meet the safety standards according to NEC (National Electrical Code) article 250.

The safety standards of the NEC article 250 require that the neutral must be grounded at the first means of disconnect (which means the nearest possible point), and cannot be grounded twice, to avoid induced transient voltages or currents.

Also extra ground connections on a neutral conductor may bypass the protection provided by a ground-fault circuit interrupter.

Section 250.4(A)(1) states that grounded electrical systems “shall be connected to earth in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation.”

If the neutrals are switched in the transfer switch, the connected neutrals in the house circuits when in transfer mode are only grounded at/bonded to the truck.

Also, the truck GFCI won't open except in the case of a real ground fault.

Though ungrounded circuits with GFCI offer you some protection (the GFCI will sense when there is a ground fault and shut off), they will not protect your electronics in the case of a power surge. You need a ground wire and surge protector for the protection against damaged electronics. Surge protectors pass the excess electricity to ground before it fries your electronics.

So removing the ground wire connection from the Lightning outlet is not a good idea.

Also if the grounding conductor is not intact or of low-impedance, the GFCI may not trip until a person provides a path. In that case, the person will receive a shock, although the GFCI should trip so quickly that the shock will not be harmful. But maybe someone with a pacemaker could experience some harm from even a mild shock?

And what if the GFCI fails to trip? Someone could be electrocuted without the ground wire providing a low impedance path to ground!

A ground connection protects against, for example, a malfunction that causes the metal frame of a tool to become energized. The equipment ground provides another path for the current to flow through the tool to ground. A GFCI protects in against a situation where there is a break in the ground circuit which could otherwise cause a shock or fire hazard.

The code require a ground connection with only a few exceptions.

Summary of Grounding Requirements

• Ground all electrical systems. [for exceptions, see 29 CFR 1926.404(f)(1)(v)]
• The path to ground from circuits, equipment, and enclosures must be permanent and continuous.
• Ground all supports and enclosures for conductors. [for exceptions, see 29 CFR 1926.404(f)(7)(i)]
• Ground all metal enclosures for service equipment.
• Ground all exposed, non-current-carrying metal parts of fixed equipment. [for exceptions, see 29 CFR 1926.404(f)(7)(iii)]
• Ground exposed, non-current-carrying metal parts of tools and equipment connected by cord and plug. [for exceptions, see 29 CFR 1926.404(f)(7)(iv)]
• Ground the metal parts of the following non-electrical equipment:
  • Frames and tracks of electrically operated cranes.
  • Frames of non-electrically driven elevator cars to which electric conductors are attached.
  • Hand-operated metal shifting ropes or cables of electric elevators.
  • Metal partitions, grill work, and similar metal enclosures around equipment of over 1kV between conductors.

Sure, if we want to get into what ifs then what if your breaker fails to trip: your wires will melt and burn your house down.

The NEC even allows you to replace ungrounded outlets in old homes with 3-prong GFI outlets because it’s safe.

 

[Henry Ford]

Based on what you're saying, how is it ever possible for a back feed breaker with a UL listed interlock on the main ever able to be safe and legal? My understanding was they are safe and legal with the neutral bonded at the generator. But it seems that only works because the generator doesn't have a GFCI? Whereas the truck is sensing the bond at the house panel as a fault so it doesn't work.?

A generator connected to a house should be a floating neutral type. In other words, the neutral is not bonded to the frame of the generator.

Some (most?) generators are configurable. The user can remove the frame bond depending on the use. Running power tools on a job site? Bond must be connected to protect the humans using the tools. Running a house? The bond must be disconnected to protect the humans in the house and the humans working on the grid.

The Lightning has a bonded neutral that is not configurable. This makes sense because it is meant to be used in the field by humans using power tools and Ford has a long history of killing its customers and knows that NOT killing its customers is best for business purposes in most cases.

Unfortunately, the bonded neutral means you can't just plug it into a power inlet box connected to an interlock on your panel. It will trip the GFCI because ground and neutral wires are connected at the panel in your house. If the truck doesn't get back the same number of electrons it sends out it assumes it has sent the extra electrons into a human and shuts off all power. Bad for people who want to power their house but good for human with a broken circular saw! Anyway...

There is a way to safely use a Lightning to power a home. You need a transfer switch that switches neutrals. This protects the entire circuit, prevents voltage leak, and is code compliant, i.e. another was to say safe. The Generac 6852 is the proven way to use your truck to power your house safely. There are probably other options.

Non-code compliant solutions are NOT SAFE. To suggest otherwise is misunderstanding the threats involved.

 

[v2h8484]

Not sure why the Whole home back up - a simple approach thread is not open to reply anymore. I would like to share some additional info in response post https://www.f150lightningforum.com/...e-back-up-a-simple-approach.18301/post-367782.

Per the post, Mike Holt certainly a trustworthy source. His advice is certainly good but I like his concise interpretation of the code even better. Here is what has said about grounding (connection to earth) and bonding (neutral-ground bond) for separately derived systems (SDS).

https://www.ecmweb.com/national-ele...-and-bonding-of-separately-derived-ac-systems

In addition, NEC 250.64 (https://up.codes/s/grounding-electrode-conductor-installation) requires the grounding electrode conductor (GEC) to be continuous without splice (sec C) except for some specific exceptions that don't apply here. Other sections (e.g. B6, smaller than 6AWG) may also apply.

IMHO, the above requirements make a Pro Power system connected to house wiring via a neutral transfer switch (i.e. SDS) with grounding via the ground pin in the L14-30 outlet and plug cable to the main panel ground (i.e. non-continuous GEC) non-code compliant.

I have seen many diagrams from Mike Holt in the past and he has always shown a separate grounding point for SDS, while non-separately derived systems usually just have one grounding point. Here is an example

https://windsorlocksct.org/wp-content/uploads/2020/09/generator_requirements.pdf

 

[luebri]

Moderators. Please do not take this thread down.

You have consistently taken down threads discussing this topic (pro-power on board, generator inlets, interlocks, and transfer kits) and it is frustrating coming from someone that is trying to learn that abruptly the discussion gets snuffed out by the moderators.

 

[Mmiketa]

Not sure why the Whole home back up - a simple approach thread is not open to reply anymore. I would like to share some additional info in response post https://www.f150lightningforum.com/...e-back-up-a-simple-approach.18301/post-367782.

Per the post, Mike Holt certainly a trustworthy source. His advice is certainly good but I like his concise interpretation of the code even better. Here is what has said about grounding (connection to earth) and bonding (neutral-ground bond) for separately derived systems (SDS).

https://www.ecmweb.com/national-ele...-and-bonding-of-separately-derived-ac-systems

In addition, NEC 250.64 (https://up.codes/s/grounding-electrode-conductor-installation) requires the grounding electrode conductor (GEC) to be continuous without splice (sec C) except for some specific exceptions that don't apply here. Other sections (e.g. B6, smaller than 6AWG) may also apply.

IMHO, the above requirements make a Pro Power system connected to house wiring via a neutral transfer switch (i.e. SDS) with grounding via the ground pin in the L14-30 outlet and plug cable to the main panel ground (i.e. non-continuous GEC) non-code compliant.

I have seen many diagrams from Mike Holt in the past and he has always shown a separate grounding point for SDS, while non-separately derived systems usually just have one grounding point. Here is an example

https://windsorlocksct.org/wp-content/uploads/2020/09/generator_requirements.pdf

Those diagrams seem odd to me as most utilities will NOT bring you an EGC, from the utility you get your phases and neutral. You're required to ground and then bond at your service equipment. To me, the ground and neutral bond should be shown at the transfer switch in those diagrams.

 

[Henry Ford]

Moderators. Please do not take this thread down.

You have consistently taken down threads discussing this topic (pro-power on board, generator inlets, interlocks, and transfer kits) and it is frustrating coming from someone that is trying to learn that abruptly the discussion gets snuffed out by the moderators.

There are two threads addressing this topic in the Back-Up Power the Home forum. There's also a policy against unsafe installations. In my experience, non-code compliant discussions are shut down and code compliant discussions stay.

This issue has been discussed a lot and there are two feasible ways to make it work. One isn't code compliant, one is.

 

[Henry Ford]

Edit: disregard. I misunderstood what this was saying.


Also...

Exception 1: Where the system bonding jumper [250.30(A)(1)] is a wire or bus bar, the grounding electrode conductor can terminate to the equipment grounding terminal, bar, or bus on the metal enclosure of the separately derived system.

 

[luebri]

There are two threads addressing this topic in the Back-Up Power the Home forum. There's also a policy against unsafe installations. In my experience, non-code compliant discussions are shut down and code compliant discussions stay.

This issue has been discussed a lot and there are two feasible ways to make it work. One isn't code compliant, one is.

...and I am trying to understand that. I have an Interlock kit. (not a transfer switch). Installed by a Certified Electrician on my 2 year old home. I asked directly if it was ok to use Bonded Neutral Generator and he said yes. I also asked our Industrial Electrician at work, and he stated yes. So I am confused how that can be deemed safe, but that same setup does not work with my truck.

 

[v2h8484]

Also...

That does not address the continuous GEC requirement.

 

[Mmiketa]

Part of the issue with a discussion like this on a forum is you do not know the qualifications of anyone weighing in, and you will always run into people who are very confidently wrong. The electrical code is not easy to read and even inspectors are known to have incorrect interpretations on occasion.

I would suggest that anyone who does not fully know what is happening with these systems not mess with them.

 

[Mmiketa]

That does not address the continuous GEC requirement.

I typically like Mike Holt, but I think this graphic from the official NEC Handbook Commentary is a little more clear. "Service" on the Mike Holt image is going to be your panelboard in most cases as you can see with the breakers indicated in the diagram. This wiring diagram would also be the correct way to make a code-compliant backup system:

 

[v2h8484]

I typically like Mike Holt, but I think this graphic from the official NEC Handbook Commentary is a little more clear. "Service" on the Mike Holt image is going to be your panelboard in most cases as you can see with the breakers indicated in the diagram. This wiring diagram would also be the correct way to make a code-compliant backup system:

I agree the graphic is bit more clear but it basically shows the same scheme of grounding and bonding on the generator that Mike Holt shows. It's more clear in that it actually calls for a "Grounding electrode nearby" for the generator.

 

[TaxmanHog]

The prior thread was going in circles with points of view supporting and disregarding the way the Lightnings PPOB safety features function, not sabotaging the grounding conductor and employing the safest equipment and wiring is exclusively supported, anything else is not.

This has been hashed over in numerous older threads and culminates with folks agreeing to disagree, leaving unskilled shade tree electricians taking liberties which could result in equipment damage in the worst of hypothetical failures, more importantly the risk to life.

 

[TaxmanHog]

The conversation has been merged back to the latest and greatest version of this issue, I'll keep it open for on going conversation.

BUT

Please, anyone who is not a licensed electrician should consult same and have their preferred PPOB integration solution ~properly~ implemented according the local code.

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