Installed Transfer Switch in House

[Gros Ventre]

I ran across this as well lately. I wasn't going to bring it up but since you did..... This EE apparently does major installations of power systems and knows the NEC well, so he has the background.

His solution is at the generator cord's plug-in box, to connect the cord's ground to the box, but do not continue the ground to the service panel.

However he has stated in his comments that:
1) He is only showing this because people need a cheaper solution than a 3 pole transfer switch for example, which is the best solution, but people will shortcut so what ways are safe?
and
2) He has not decided if this is a safe solution for a F-150 PowerBoost. I just asked again and he said he hasn't decided yet.

Presumably because the F-150 is on rubber tires and is not earth grounded, which possibly complicates the idea of it being a "separately derived system" since breaking the ground wire between the cord plug-in and the breaker panel removes the earth ground connection for the ground wire (yet the circuit from the F-150 TO the cord plug-in box still has a ground return so GFCI still works on that portion of it). This is in contrast to the neutral switching transfer panel (e.g. Generac 6852), which carries the ground wire through it to the load panel which goes to the earth ground rod.

Note this is NOT the same as removing the ground pin on your 30A cord from the PB to the plug-in box, that provides NO protection when you are anywhere from the F150, along the cord, up to the plug-in box.

Here is one of his diagrams, which will be helpful to reference for discussion, showing the disconnected ground wire from the plug-in box to the main breaker panel.
Also note that he shows the generator tied to an earth ground - but he said in a comment reply that is not needed as the main load panel already has a ground rod. ? And I'm wondering about how GFCI would work on the main panel breakers that has it. So confusing.

What do you electricians think (don't guess or presume like me, if you don't know please).

The Green Box labels this as the backside of a NEMA Box. Not really. Look carefully: It is a standard junction box linked to the NEMA Plug Box on the outside using a threaded pipe nipple to join the two thru the house wall.

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[Snooker_ML]

The Green Box labels this as the backside of a NEMA Box. Not really. Look carefully: It is a standard junction box linked to the NEMA Plug Box on the outside using a threaded pipe nipple to join the two thru the house wall.

Wait! I (ME, not the original creator), edited and added the descriptive text on that screen capture, trying to help summarize it. My intent was to say "the 4 wires from the NEMA 14-30 cord from your Powerboost are plugged into an outlet behind this box".

Is this the only thing you can comment on? I'm disappointed. I'm trying to add a discussion to a potentially real solution for all of us. It is fully outlined in the YouTube, I'm just trying to summarize it with a couple of photos. Go to the source for the details.

 

[Gros Ventre]

Wait! I (ME, not the original creator), edited and added the descriptive text on that screen capture, trying to help summarize it. My intent was to say "the 4 wires from the NEMA 14-30 cord from your Powerboost are plugged into an outlet behind this box".

Is this the only thing you can comment on? I'm disappointed. I'm trying to add a discussion to a potentially real solution for all of us. It is fully outlined in the YouTube, I'm just trying to summarize it with a couple of photos. Go to the source for the details.

I found nothing else worth commenting on. The electrical issues this guy raises are accurate and safe in my observation. The only question is whether the NEC would like that wiring. Much as I think his method is safe and reliable, I'm not about to make any kind of recommendation. Since the electrical circuitry provides ground paths when needed and the interlock (required by the NEC) prevents any issue when powered from the local distribution system, the discussion should be directed toward whether the NEC would accept it or not.

 

[Snooker_ML]

Fair enough, certainly not expecting your blessing, but I was hoping someone might comment on my last 2 questions. About the grounding rod shown at the generator, since we don't have one on the truck. And without the generator being earth grounded, if there is a fault will the F150 GFCI still trip? In particular, how about this fault, which I will exaggerate for clarity:

On your 4 wire cord from the F150 to your plug-in box for your house, let's say the insulation on the cord gets nicked and the hot black wire is exposed, and you are barefoot on the ground in the rain. You pick up the cord and touch the exposed hot wire. There is no path back to the F150 generator into its ground wire, in fact the fault current will flow through your body to the house ground rod to the neutral, so that ALL the return current will return through the neutral to the generator so the generator will not trip.

Hmm, the more I think about it, this is a real problem. Thoughts?

 

[Hullguy]

I ran across this as well lately. I wasn't going to bring it up but since you did..... This EE apparently does major installations of power systems and knows the NEC well, so he has the background.

His solution is at the generator cord's plug-in box, to connect the cord's ground to the box, but do not continue the ground to the service panel.

However he has stated in his comments that:
1) He is only showing this because people need a cheaper solution than a 3 pole transfer switch for example, which is the best solution, but people will shortcut so what ways are safe?
and
2) He has not decided if this is a safe solution for a F-150 PowerBoost. I just asked again and he said he hasn't decided yet.

Presumably because the F-150 is on rubber tires and is not earth grounded, which possibly complicates the idea of it being a "separately derived system" since breaking the ground wire between the cord plug-in and the breaker panel removes the earth ground connection for the ground wire (yet the circuit from the F-150 TO the cord plug-in box still has a ground return so GFCI still works on that portion of it). This is in contrast to the neutral switching transfer panel (e.g. Generac 6852), which carries the ground wire through it to the load panel which goes to the earth ground rod.

Note this is NOT the same as removing the ground pin on your 30A cord from the PB to the plug-in box, that provides NO protection when you are anywhere from the F150, along the cord, up to the plug-in box.

Here is one of his diagrams, which will be helpful to reference for discussion, showing the disconnected ground wire from the plug-in box to the main breaker panel.
Also note that he shows the generator tied to an earth ground - but he said in a comment reply that is not needed as the main load panel already has a ground rod. ? And I'm wondering about how GFCI would work on the main panel breakers that has it. So confusing.

What do you electricians think (don't guess or presume like me, if you don't know please).

I don’t care if this guy is an EE or not! By only connecting the ground to the metal box the only part of his system that is grounded is the box. PVC pipe further isolates the system and by code you have to run and attach a ground when using PVC.

don’t ask me how many times I’ve had to fix EE’s mist

 

[Gros Ventre]

My thought is that you're screwed no matter how this plays out with regard to the box bonding or not. But I'll remember not to do generator hookups barefoot in the rain...
On the other hand, having set up a generator for my house multiple times... I do the entire cabling thing with every thing dead. I don't startup the generator until all cables are connected and intact. Similarly when I shutdown a hookup, I shutdown the generator first then disconnect the cables. For either warmup or cooldown time, I meet that after cables are connected or before cables are disconnected and the engine shutdown.

 

[marekjk]

Fair enough, certainly not expecting your blessing, but I was hoping someone might comment on my last 2 questions. About the grounding rod shown at the generator, since we don't have one on the truck. And without the generator being earth grounded, if there is a fault will the F150 GFCI still trip? In particular, how about this fault, which I will exaggerate for clarity:

On your 4 wire cord from the F150 to your plug-in box for your house, let's say the insulation on the cord gets nicked and the hot black wire is exposed, and you are barefoot on the ground in the rain. You pick up the cord and touch the exposed hot wire. There is no path back to the F150 generator into its ground wire, in fact the fault current will flow through your body to the house ground rod to the neutral, so that ALL the return current will return through the neutral to the generator so the generator will not trip.

Hmm, the more I think about it, this is a real problem. Thoughts?

That’s a good question! I’m eager to hear what everyone thinks.

 

[HammaMan]

I don’t care if this guy is an EE or not! By only connecting the ground to the metal box the only part of his system that is grounded is the box. PVC pipe further isolates the system and by code you have to run and attach a ground when using PVC.

don’t ask me how many times I’ve had to fix EE’s mist

That image is missing info and what is going on with the box floating on 2 1/2" runs. Either the box is improperly secured or it's improperly secured smashing 2 PVC conduit runs. I think this is the work of an overnight holiday inn EE.

 

[Snooker_ML]

That image is missing info and what is going on with the box floating on 2 1/2" runs. Either the box is improperly secured or it's improperly secured smashing 2 PVC conduit runs. I think this is the work of an overnight holiday inn EE.

To be fair, if you did't watch his entire video (and his previous part 1), then you cannot judge his solution by this one shady looking box. Look closely at the image I posted of his circuit drawing - his whole point was to NOT connect the ground wire from the box (and from neutral bonded generator) back to the main service panel ground. That is what is under debate. Did you watch his entire video(s)? Did you study his drawing that I posted, as an example - there are many more in his video.

I'm not saying you're wrong, I don't know. You certainly would not want this setup when connecting to the main panel box for normal household outlets. This one is a separately switched circuit only for the generator path to the panel.

 

[Snooker_ML]

I don’t care if this guy is an EE or not! By only connecting the ground to the metal box the only part of his system that is grounded is the box. PVC pipe further isolates the system and by code you have to run and attach a ground when using PVC.

don’t ask me how many times I’ve had to fix EE’s mist

I couldn't agree more. On the surface that is, but did you want the entire video and study it? It's a lot to ask, but one picture of an ungrounded box means nothing.

I'm an EE but have zero power experience, only electronics and software. I am just trying to figure this out to get ideas for my electrician. I've already had one turn me down - most have never switched neutrals in a transfer panel, etc.

Most EE's have no clue and certainly are not trained with NEC codes, but this guy does Power distribution designs for large buildings (I think) and said in his video he went back through several NEC code versions to help him decide, and is very familiar. This isn't an engineer vs electrician debate - I'd normally go with the electrician personally.

But... Like i said in my previous reply, not connecting the metal box ground to the service panel ground was the entire point of his proposed solution for a neutral bonded generator. If you watched it all then maybe you have a more specific comment. I hope if you haven't you will watch it. It's a big question to me about the fact that the F150 neutral bonded to ground is not also attached to an earth ground rod, as in his proposals - though he isn't sure about if you need it and won't comment yet.

 

[Gros Ventre]

Well, the core issue is that the F-150 PowerBoost Generator will shutdown when connected to a "Normal" house panel (one where the neutral is unswitched). So people are looking for a workaround instead of having to spend big bucks to make the house fit the truck. This proposal disconnects the house gound wire from the inlet box. This then stops the truck system from sensing a second neutral-ground bond by breaking it. So the truck will power your house (I did a test and it does work that way). So the next question is whether it is safe to operate that way. Electrically and via the house internal Neutral-Ground bond, the truck is grounded to earth and both sides of the truck to house ground wires are grounded. So now the question is whether the GFCI will protect you from touching a damaged truck to house cable while you're standing barefoot in a puddle of water since the sensing of the GFCI (neutral vs ground wire currents) might be bypassed. It is apparently bypassed since the return path for the current coursing thru your body goes thru earth to the house ground to the house neutral-ground bond and then solely thru the house neutral wire to the truck system neutral wire, which gets the current back to its source... It appears that since there is zero current on the truck ground wire and all of the current on the trucks neutral wire the GFCI won't trip... This is a joke: Frankly, I'd get rid of the puddle and at least wear flip-flops. Another joke: For those of you that have run portable generators that had no GFCI feature, no sweat, business as usual.

 

[Gros Ventre]

Ya know... My house panel is full and I'd like to replace it with a panel with more breaker slots. If the electric industry would make a whole house panel with a neutral switching capability, I'd buy it in a heartbeat... but all they offer is these wimpy emergency panels with only 8 breaker slots. Get over it electric industry, this truck will run the whole house although with a bit of load management for the hot-water heater, dryer, and oven. Who knows maybe when these three give up the ghost, I'll replace them with propane units... Then the whole house will be well within the capability of the truck...

 

[Snooker_ML]

Well, the core issue is that the F-150 PowerBoost Generator will shutdown when connected to a "Normal" house panel (one where the neutral is unswitched). So people are looking for a workaround instead of having to spend big bucks to make the house fit the truck. This proposal disconnects the house gound wire from the inlet box. This then stops the truck system from sensing a second neutral-ground bond by breaking it. So the truck will power your house (I did a test and it does work that way). So the next question is whether it is safe to operate that way. Electrically and via the house internal Neutral-Ground bond, the truck is grounded to earth and both sides of the truck to house ground wires are grounded. So now the question is whether the GFCI will protect you from touching a damaged truck to house cable while you're standing barefoot in a puddle of water since the sensing of the GFCI (neutral vs ground wire currents) might be bypassed. It is apparently bypassed since the return path for the current coursing thru your body goes thru earth to the house ground to the house neutral-ground bond and then solely thru the house neutral wire to the truck system neutral wire, which gets the current back to its source... It appears that since there is zero current on the truck ground wire and all of the current on the trucks neutral wire the GFCI won't trip... This is a joke: Frankly, I'd get rid of the puddle and at least wear flip-flops. Another joke: For those of you that have run portable generators that had no GFCI feature, no sweat, business as usual.

Thank you for that detailed response. For this proposal, as you stated, the inlet box (where you connect your cable from the truck) has its metal box connected to the truck ground, but not to the main house panel. It seems to me that all you would need to do is bond this metal inlet box to an earth grounding rod AT THE BOX, and the GFCI at the truck would trip.

The portion from the inlet box to the house panel is done once and is not tampered with, meaning it is not an area you normally touch or have exposure to elements. But once you pull up a truck generator in a blizzard when your power is out and moisture is everywhere, AND you attach a cable that possibly could be worn or damaged and you didn't know it... well I feel like I would not want to try a solution that wasn't safe.

I do think there is some credence to the idea I've read that the NEC and GFCI need to constantly evolve and address these new technologies. I think it is possible that a solution will address our need in the NEC (or whatever org controls this, I'm not a power guy). And yes, a breaker panel with a neutral disconnect - c'mon what is taking them so long?

Just an aside about new electrical technology - please don't comment and derail this useful thread...
Today on Denver 9News there was a story about a fire in a house garage - unknown source. When firefighters arrived and sprayed water in the garage there was a huge explosion that blew a double wide garage door 35 feet away.
The explosion occurred because the firefighters did not know the car in the garage was plugged into a Level 2 charger!!! Water and high voltage - be it batteries in a car or a line voltage, do not mix. The story was about how fire dept's are having to adapt with new methods and training. I was guessing the solution would have been some kind of non conducting foam they could spray, but no, the solution was like a big blanket you drape over a car, starve the oxygen, and wait 3 days.

 

[Gros Ventre]

Thank you for that detailed response. For this proposal, as you stated, the inlet box (where you connect your cable from the truck) has its metal box connected to the truck ground, but not to the main house panel. It seems to me that all you would need to do is bond this metal inlet box to an earth grounding rod AT THE BOX, and the GFCI at the truck would trip.

The portion from the inlet box to the house panel is done once and is not tampered with, meaning it is not an area you normally touch or have exposure to elements. But once you pull up a truck generator in a blizzard when your power is out and moisture is everywhere, AND you attach a cable that possibly could be worn or damaged and you didn't know it... well I feel like I would not want to try a solution that wasn't safe.

I do think there is some credence to the idea I've read that the NEC and GFCI need to constantly evolve and address these new technologies. I think it is possible that a solution will address our need in the NEC (or whatever org controls this, I'm not a power guy). And yes, a breaker panel with a neutral disconnect - c'mon what is taking them so long?

Just an aside about new electrical technology - please don't comment and derail this useful thread...
Today on Denver 9News there was a story about a fire in a house garage - unknown source. When firefighters arrived and sprayed water in the garage there was a huge explosion that blew a double wide garage door 35 feet away.
The explosion occurred because the firefighters did not know the car in the garage was plugged into a Level 2 charger!!! Water and high voltage - be it batteries in a car or a line voltage, do not mix. The story was about how fire dept's are having to adapt with new methods and training. I was guessing the solution would have been some kind of non conducting foam they could spray, but no, the solution was like a big blanket you drape over a car, starve the oxygen, and wait 3 days.

Ya know... We'll have to try that idea of putting in a ground rod at the inlet box. You're right, it would be able to trip the GFCI. The question then is would the GFCI Trip as it does now, just because it was hooked up. Would it be able to tell that there were two neutral-ground bonds? As an aside, the way you avoid the scenario where a damaged cable is hazarous in bad weather is to do all of the connections with the house and generator off. Only when all is connected do you power-up the generator and then the house. In my case when I power-up the generator I let it idle forabout 5 minutes before I flip the in-house breaker. Conversely when shutting down, open the inhouse breaker, allow the generator to idle for maybe 5 minutes, then shut it down. Only then do you touch the cables. This kind of procedure isn't really purely self protective. As I see it it is generally a "good engineering practice" to do this so that you don't inadvertently pull a powered plug under load or plug in and energize a plug by the act of plugging it in.

 

[Gros Ventre]

Frankly this looks like it will sense that there is another neutral-ground bond out there. Effectively the generator will see that the neutral wire makes it to the house ground rods. Thence via the earth to the ground rods at the inlet box. Thence via the ground wire and back into the generator. Hm-m-m-m... if the earth link (EG ground rods to ground rods) is a high enough resistance link, then no problem and no trip. On the other hand if it is low enough resistance, then I suppose the GFCI in the F-150 Generator will sense it and trip... What do you think?

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