UL-458. What's the worst that could happen?

[Terrapin]

OK, so people have been trying to help me out with an inverter to tie into an existing camper's AC system.

I have read quite a bit of technical info, and I do honestly believe there is some reason why you shouldn't just plug your shore power into your inverter. But I just haven't wrapped my head around exactly how a problem could arise. I guess I am asking for an example of the circumstance or situation that would cause a hazard minus the electrician lingo. I think if I could understand what electricity went where it was not supposed to and by what path that it should not this would make a lot more sense.

Using the example of doing exactly that. plugging a shore power cord into a stand alone solar generator that is grounded to both the trailer and a pipe driven into the ground is really what I am asking. I just see so many videos and such endorsing it as the easiest way to get started in boondocking with a trailer that it's amazing to here how dangerous it can be, and those videos don't even mention being sure to ground the inverter to either earth or the chassis.

Anyone care to try to help me, and I am sure may other, sort this out?

 

[techguy22]

I'm installing a system in my RV right now and this guide that was in the resources section was really helpful for me to figure out the grounding of my inverter properly. I'm using a sungold 3000 watt inverter.

Grounding Made simpler - Part 4: Mobile systems.

To get the paper, click on the orange button at the top of the screen. The subject of grounding is a complex, multifaceted subject, that is often treated as an after-thought but needs to be considered from the beginning of the design and build...

diysolarforum.com

 

[John Frum]

DISCLAIMER: I am not an electrician.

SIMPLE ANSWER: somebody could die, either by fire or electrocution.

I'm not going to answer your question as asked but instead give you more questions to answer.
I suggest you get an electrician to explain this to you or better yet just do the work.
Grounding is a complicated confusing multi-faceted subject.

Lets look at one small visible part of the ball of confusion.
Some of your 120 volt appliances have 3 conductor leads.
Those conductors are hot, neutral and ground.
Why 3 wires?
Some of your 120 volt appliances have 2 conductor leads.
Those conductors are hot and neutral.
Why 2 wires?

What do each of those wires do?
Why is hot called hot?
Why is neutral called neutral?
Why is ground called ground?

Assuming you have a house, in the service entrance panel their is a little green screen that bonds the neutral and ground bus bars.
What is the significance of that green screw and the bond it creates?
Why is it only in the service entrance panel and not in any of the sub panels?
How does a mobile application complicate the neutral/ground bond?

 

[chrisski]

I have the inverter fed in through the shore power cable.

I use my trailer about a week a month in the six month RV season.

One thing that could be bad is wiring higher than 15 amps of AC output through a plug designed for 15 amps. Like wiring enough amps to run a 15,000 BTU roof top AC through from your inverter to shore power using an extension chord. THis is basically using a 3000 watt and higher inverter‘s entire output through an extension cord. I have a 2000 watt inverter, and not counting surge, that is almost 17 amps. I plug into a 15 amp GFCI outlet and have not hardwired it to the RV using the 20 amp screws.

The biggest hazard is not shutting the RV converter off so the Battery DC power turns itself into AC Power, reaches the RV’s built in AC to DC converter converter and then tries to send 15 charging amps to the battery. I don’t know how bad that is, but when I accidentally left the circuit breaker on while running shore power, the my power conemptiopn went to 700 watts to 1000 watts when the converter was pulling power and I heard a clicking which I think was the self resetting breakers going off.

Will hard wiring the inverter to the AC system fix this? Absolutlely not. The converter problem needs to fixed, and the easiest way is to flip the converter breaker.

Then, after you have a hard wiring solution, you need to have a way that if solar power is on and the inverter is working, that if you go to plug the Shore power into the RV jack, you’re not sending live power into the three or four prongs you’ll be handling as you plug it in and also are not sending out of phase AC at each other when you plug it in.

You can buy an auto transfer switch to keep this from hurting someone or ruining equipment. There’s a couple different types like Generator/solar power, or generator shoots power/PV/shore power. For me, the transfer switches I looked at were not off the shelf plug and play, but require a bit of thought before buying and writing/install.

 

[John Frum]

You can buy an auto transfer switch to keep this from hurting someone or ruining equipment.

Please link to a discrete auto transfer switch that switches the neutral/ground bond.

 

[time2roll]

No issues with a stand alone "solar generator" to just set it on the ground and plug in same as you would with any gasoline generator. The plug itself will ground connect the generator and the RV.

 

[time2roll]

Please link to a discrete auto transfer switch that switches the neutral/ground bond.

All transfer switches that I know switch the Hot & Neutral only. Ground is always common and connected.

 

[John Frum]

No issues with a stand alone "solar generator" to just set it on the ground and plug in same as you would with any gasoline generator. The plug itself will ground connect the generator and the RV.

Are we talking about a stand alone system?
If we are then my previous statements don't apply.
Ever notice that the solar generators have a space where the ground pin of a 3 prong conductor would go.
I mean they are a 2 prong outlet with a hole where the ground would go.

 

[John Frum]

I apologise I had it wrong.

mains<->inlet<->surge_protector<->
                                  ats<->distribution_panel
                       inverter<->

For the mains side the neutral ground bond is upstream of the pedestal.
For the inverter side the neutral ground bond is at the inverter.
Neutral and ground are not bonded at the distribution panel.
Ground is common.
If the transfer switch switches both neutral and ground and defaults to the inverter then it should be fine.
I had it in my head that the discrete ats only switched the hot.
Thanks for setting me straight.

 

[Terrapin]

DISCLAIMER: I am not an electrician.

SIMPLE ANSWER: somebody could die, either by fire or electrocution.

I'm not going to answer your question as asked but instead give you more questions to answer.
I suggest you get an electrician to explain this to you or better yet just do the work.
Grounding is a complicated confusing multi-faceted subject.

Lets look at one small visible part of the ball of confusion.
Some of your 120 volt appliances have 3 conductor leads.
Those conductors are hot, neutral and ground.
Why 3 wires?
Some of your 120 volt appliances have 2 conductor leads.
Those conductors are hot and neutral.
Why 2 wires?

What do each of those wires do?
Why is hot called hot?
Why is neutral called neutral?
Why is ground called ground?

Assuming you have a house, in the service entrance panel their is a little green screen that bonds the neutral and ground bus bars.
What is the significance of that green screw and the bond it creates?
Why is it only in the service entrance panel and not in any of the sub panels?
How does a mobile application complicate the neutral/ground bond?

This! all of this Joey...At least you get the question! And I noticed here again how so many are not even addressing the true nature of the question, but ARE trying to help, so thanks to you all for that for that... but be aware, there are shades of things amiss

But once again in the replies that truely address the nature of my question left me in the dust... So I am off to learn of things AC theory...

In the meanwhile. Just one question set for now. As my self built battery, inverter, solar panel, and Aims battery charger are built into a suitcase with no charging system from the trailer ever wired to recharge it (a genset independent from the trailer will power the aims charger as needed) I have used the term "stand alone solar generator". Am I using that term correctly or not? Am I good to go with plugging my trailer shore cord into it? Is grounding to each of the components of the "stand alone solar generator" warranted and would it be to the trailer or to a copper stake driven into mother earth. (I am even scared to use the word ground incorrectly now LMAO). I am wondering if I am overthinking it......PS I did note that the aims battery charger does hold the UL-458 cert you brought to my attention It has a pretty large parasitic draw so it will be on a breaker and shut away when not in use...I have no clue if it matters but it's there.

TO ANYONE ELSE AS WELL,
I think I may be asking far too much for a education in AC theory by anyone here. I get it. So maybe if anyone knows of a free novice online education resource, or a video series on YouTube about AC theory so I can keep my family safe from me I would greatly appreciate a link or push that direction.

 

[John Frum]

As my self built battery, inverter, solar panel, and Aims battery charger are built into a suitcase with no charging system from the trailer ever wired to recharge it (a genset independent from the trailer will power the aims charger as needed) I have used the term "stand alone solar generator".

If this system is not integrated into the trailer ac wiring then personally I'm less concerned about the neutral/ground bond rules.
My generator has a floating neutral and I don't worry excessively about plugging 3 prong devices into its outlets.
I do get concerned when you integrate with the 3 prong outlets that someone who doesn't know any better might plug something into and get a shock.

 

[Terrapin]

If this system is not integrated into the trailer ac wiring then personally I'm less concerned about the neutral/ground bond rules.
My generator has a floating neutral and I don't worry excessively about plugging 3 prong devices into its outlets.
I do get concerned when you integrate with the 3 prong outlets that someone who doesn't know any better might plug something into and get a shock.

If I understand correctly using a standard dogbone 15a to 30a to plug the shore power into the completely otherwise "stand alone" inverter's output is not what you are worried about as integrating it? If so, does that change if I were to correctly wire a 30a female socket in a junction box that would be a part of the "stand alone generator" for use as a higher powered outlet from the inverters hardwire capability?

 

[John Frum]

If I understand correctly using a standard dogbone 15a to 30a to plug the shore power into the completely otherwise "stand alone" inverter's output is not what you are worried about as integrating it?

By integration I mean connecting directly or indirectly to the the rv's ac distribution panel and even more indirectly to 3 prong receptacles in the trailer.

If so, does that change if I were to correctly wire a 30a female socket in a junction box that would be a part of the "stand alone generator" for use as a higher powered outlet from the inverters hardwire capability?

Not really following as its after drink o'clock.

 

[time2roll]

If you are going to hardwire an inverter to an RV make sure it is compatible. Many do not like the ground, chassis ground and 12 volt negative connected. Read the manual carefully before you click and buy.

If the battery and inverter are isolated then about anything should work. Just plug in the main cord.

 

[Terrapin]

If you are going to hardwire an inverter to an RV make sure it is compatible. Many do not like the ground, chassis ground and 12 volt negative connected. Read the manual carefully before you click and buy.

If the battery and inverter are isolated then about anything should work. Just plug in the main cord.

I am hearing more about this being Ok... I got questioned on it after considering making things autoamtic with a transfer switch... but I am much better now.

So the inverter is had hardwire capabilities and the only connection when in use wioll be through the RV shore power cord. My last question was this. Because the instructions say to use the hardwire capability for large loads, can I simply wire a 3 prong female otlet to match the one on the shore power 30a cord of the trailer. I know I will not have full 30a capability just by installing a receptacle. But based on the recommendation of the the Giandel inverter instructions, to squeeze the most out of it in surge situations, can I use that receptacle (correctly wired and mounted on my stand alone generator) without incurring the wrath of the grounding gods?

 

[time2roll]

I think you will get full power just fine out of the 5-15 connector. These are made virtually the same ampacity as a 5-20 connector except the 5-20 has a "T" shaped neutral. Certainly if you are permanently mounting and wiring the inverter to the RV by all means use the hardwire provision. This also keeps the outlet available to plug power tools in for outside work.

 

[John Frum]

I am hearing more about this being Ok... I got questioned on it after considering making things autoamtic with a transfer switch... but I am much better now.

A stand alone system should not have a transfer switch.
Some of the cheap solar generators do but, that just demonstrate contempt on the part of the manufacturer in my opinion.

So the inverter is had hardwire capabilities and the only connection when in use wioll be through the RV shore power cord. My last question was this. Because the instructions say to use the hardwire capability for large loads, can I simply wire a 3 prong female otlet to match the one on the shore power 30a cord of the trailer. I know I will not have full 30a capability just by installing a receptacle. But based on the recommendation of the the Giandel inverter instructions, to squeeze the most out of it in surge situations, can I use that receptacle (correctly wired and mounted on my stand alone generator) without incurring the wrath of the grounding gods?

Will try to parse this tomorrow.

 

[Terrapin]

I think you will get full power just fine out of the 5-15 connector. These are made virtually the same ampacity as a 5-20 connector except the 5-20 has a "T" shaped neutral. Certainly if you are permanently mounting and wiring the inverter to the RV by all means use the hardwire provision. This also keeps the outlet available to plug power tools in for outside work.

the outlet proposed is the TT-30 with the offset 45 degree angles. The reason that I may not be able to use my dogbone on the inverter face is because the position of the grounding screw is very close and off set to the side between the two outlets. So since I need to do something anyways I figured I'll just use this https://www.homedepot.com/p/Leviton...w-Single-Outlet-Black-R10-07313-S00/300324450

 

[John Frum]

I think you will get full power just fine out of the 5-15 connector. These are made virtually the same ampacity as a 5-20 connector except the 5-20 has a "T" shaped neutral.

The receptacle may be fine but its the wire behind it is what concerns me.

 

[John Frum]

Are we are talking about connecting a stand alone system(solar generator) to the rv inlet?
If this is true then use a grounding plug to bond neutral and ground.