Frame grounding shore/inverter 120v power?

justinm001

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Should I have my shore ground and breakers and other things grounded to the RV's frame or directly to the ground wiring? My coach is stainless steel including half of the outside and once while camping we cracked our 50a shore cable end but still used it not realizing how cracked it was. Well it energized my entire coach a bit and since it sits on massive tires when we touched the outside I could feel a decent shock, wife couldn't because she had flip flops but once she took them off she could.

I'm replacing my shore input from a metal box to a plastic box and now wondering if I should also replace my shore breaker box or at least make sure the ground isn't mounted to the frame in the box.

An energized load will take the path of least resistance and since we use long shore cables and RV's sit on rubber we'll more likely to become the path of least resistance. This is different than homes and other areas as they don't have huge rubber insulating them from physical ground.
 
energized load will take the path of least resistance
No. It will take any paths at any time.
wondering if I should also replace my shore breaker box or at least make sure the ground isn't mounted to the frame in the box.
The ground/bare/green should always be connected to the source of power
That means that shorepower provides the safety ground.
Safety ground should be contiguous with the coach wiring with a separate ground to the frame.
make sure the ground isn't mounted to the frame in the box
It should NOT be connected to the N/white but the box should be grounded or the wires in it grounded.
This is different than homes and other areas as they don't have huge rubber insulating them from physical ground.
The issue isn’t the ground, the issue is the damaged shorepower cable; in a fault the ground should enable the breaker to trip.
I’d also see about GFCI breaker(s).
 
No. It will take any paths at any time.

The ground/bare/green should always be connected to the source of power
That means that shorepower provides the safety ground.
Safety ground should be contiguous with the coach wiring with a separate ground to the frame.

It should NOT be connected to the N/white but the box should be grounded or the wires in it grounded.

The issue isn’t the ground, the issue is the damaged shorepower cable; in a fault the ground should enable the breaker to trip.
I’d also see about GFCI breaker(s).
I disagree about electricity taking any path but I can see your point. A good example of how electricity travels is by looking at a lichtenberg table. Its actually the entire point on why we have ground wires as to provide a safer path for energy.

You're kinda skipping over my question and providing generalized answers. I'm specifically asking about frame ground as in grounding the breaker panel and shore panel boxes to the frame WITH the shore ground. Generally with metal electrical boxes and all fixtures they'll attach the green ground wire physically to the box along with the connections so not only is the wiring grounded but the box is as well. This provides protection incase an issue so everything returns to ground.

For homes and most things this makes perfect sense but with RVs and especially metal ones like mine and airstreams it seems like a larger risk because metal is physically exposed. Also seems like a much larger lightning risk being frame grounded.

Correct the issue wasn't the ground in this case but the damaged shorepower cable. But these cables are on the exterior and can easily be damaged as well as CG pedestals or pins and there isn't any way to tell if your ground is working properly unless you have a surge protector that monitors.

I don't think a GFCI is the answer but a high quality surge protector. I think I have this model or something like it in my garage I need to find then wire up
 
disagree about electricity taking any path but I can see your point. A good example of how electricity travels is by looking at a lichtenberg table. Its actually the entire point on why we have ground wires as to provide a safer path for energy
I usedta think along those lines but realized that anything can be ‘hot’ at any time in a fault; as definitively explained on this forum with a four-hour read of a thread along with Mike Holt references folks provided; electricity takes parallel paths. Not preferred ones- any available path gets used simultaneously.
And no: the entire point we use ground is to provide a secondary path to open a safety disconnect in the case of a failure/fault. It insures the breaker trips or fuse blows.
It should never be part of a current carrying circuit.
don't think a GFCI is the answer but a high quality surge protector
What? The GFCI opens if milliseconds of milliamps unbalance the H and N. A surge protector regardless of quality will still kill you - GFCI is a safety device
You're kinda skipping over my question and providing generalized answers. I'm specifically asking about frame ground as in grounding the breaker panel and shore panel boxes to the frame WITH the shore ground.
no:
The ground/bare/green should always be connected to the source of power
That means that shorepower provides the safety ground.
Safety ground should be contiguous with the coach wiring with a separate ground to the frame.
It should NOT be connected to the N/white but the box should be grounded or and the bare/green wires in it grounded
That’s specific, not general. Maybe I didn’t explain it well. @timselectric ?
specifically asking about frame ground as in grounding the breaker panel and shore panel boxes to the frame WITH the shore ground
yes it should be grounded, just not bonded to N
with RVs and especially metal ones like mine and airstreams it seems like a larger risk because metal is physically exposed. Also seems like a much larger lightning risk being frame grounded.
no.
electricity doesn’t follow a map of wiring, it follows its own rules. A metal space frame protects from lightning (van de graaf effect) so a total metal enclosure like a metal car or more so a big metal cocoon / wheeled zeppelin will protect from lightning better than anything (airplanes get struck by lightning and survive).
Generally with metal electrical boxes and all fixtures they'll attach the green ground wire physically to the box along with the connections so not only is the wiring grounded but the box is as well. This provides protection incase an issue so everything returns to ground.
sorta. The green/bare/ground should NEVER connect “along with the connections” in an rv without specific use of an isolation/transfer switch.
This provides protection incase an issue so everything returns to ground
Nope. It is there to trip the breaker or blow a fuse. Only.
there isn't any way to tell if your ground is working properly unless you have a surge protector that monitors
I think you can buy a $30 thingy to check for open ground and such. You don’t need a surge protector for that.
think I have this model or something like it in my garage I need to find then wire up
There’s more to know than that.
I’m not recommending this particular model but it’s the first thing my search revealed

Do you have solar and an inverter onboard?
 
I usedta think along those lines but realized that anything can be ‘hot’ at any time in a fault; as definitively explained on this forum with a four-hour read of a thread along with Mike Holt references folks provided; electricity takes parallel paths. Not preferred ones- any available path gets used simultaneously.
And no: the entire point we use ground is to provide a secondary path to open a safety disconnect in the case of a failure/fault. It insures the breaker trips or fuse blows.
It should never be part of a current carrying circuit.

What? The GFCI opens if milliseconds of milliamps unbalance the H and N. A surge protector regardless of quality will still kill you - GFCI is a safety device

no:

That’s specific, not general. Maybe I didn’t explain it well. @timselectric ?

yes it should be grounded, just not bonded to N

no.
electricity doesn’t follow a map of wiring, it follows its own rules. A metal space frame protects from lightning (van de graaf effect) so a total metal enclosure like a metal car or more so a big metal cocoon / wheeled zeppelin will protect from lightning better than anything (airplanes get struck by lightning and survive).

sorta. The green/bare/ground should NEVER connect “along with the connections” in an rv without specific use of an isolation/transfer switch.

Nope. It is there to trip the breaker or blow a fuse. Only.

I think you can buy a $30 thingy to check for open ground and such. You don’t need a surge protector for that.

There’s more to know than that.
I’m not recommending this particular model but it’s the first thing my search revealed

Do you have solar and an inverter onboard?
Interesting not sure exactly how lightning works but assumed more metal means more of a risk. Need to research more.

I think you're missing my question. I get there should be a ground but should it be bonded to the frame as in should I be using metal enclosures or does that increase a risk since my whole bus is metal?

Sure a gfci would be ideal in a perfect scenario but I'm assuming some CGs have poor ground and it'll cause more issues than good.

Yes 1800w solar and 2 inverters on separate systems one 12v other 48v all Victron. It also concerns me with how ground works in a system with inverters as my input flows through both inverters (one on each leg) including ground then separate ground from inverters to circuit breakers. If frame has ground bonded then the neutral can bypass the inverters and bypass the surge protectors and even the breakers as the frame is connected to circuit breakers, inverters the shore power breaker AND the shore power box and cable to the pedestal.
 
All exposed conductive surfaces should be grounded for safety of people.
 
This is correct for a house and I meant both when discussing frame grounding.... I see the confusion. Metal enclosures usually have the ground terminal screwed into the enclosure.

Having ground bonded to the frame seems like a major risk. Even more so since all my DC systems are also neutral grounded.
 
This is correct for a house and I meant both when discussing frame grounding.... I see the confusion. Metal enclosures usually have the ground terminal screwed into the enclosure.

Having ground bonded to the frame seems like a major risk. Even more so since all my DC systems are also neutral grounded.
I'm not doing this again, with you.
Do whatever you want. Good luck.
 
I'm not doing this again, with you.
Do whatever you want. Good luck.

I'm just confused on how grounding to the frame makes it safer for people. Agree if a house. Let me rephrase. Say if my RV isnt connected to shore and on massive rubber tires. And say my floor is made of conductive stainless steel bonded to frame. Wouldn't I risk the ground becoming energized if frame was ground bonded?

I'm just trying to understand the WHY and make sure it's safe and not just the standard way
 
Having ground bonded to the frame seems like a major risk.
Reread what I wrote and then look at the ‘grounding’ paper in the FAQ (resources section). You aren’t fully informed- yet. Not a criticism, just a fact.
Even more so since all my DC systems are also neutral grounded.
DC systems should NEVER be anywhere near a neutral (AC systems have neutral, the 180* partner of the H/L1
confused on how grounding to the frame makes it safer for people. Agree if a house. Let me rephrase. Say if my RV isnt connected to shore and on massive rubber tires. And say my floor is made of conductive stainless steel bonded to frame. Wouldn't I risk the ground becoming energized if frame was ground bonded
no.
The ground in DC is both part of the load circuit and the ‘safety ground’ in a manner of speaking- but the actual safety is that IF the pos(+) contacts something else it shorts and trips the breaker or fuse. Because no matter what you think an unprotected DC circuit can cause a fire without blowing a fuse if not provided with that chassis bond; higher impedance current makes heat, heat makes fire.
Properly grounded the body/frame/chassis cannot be “energized.”

In an AC system, the current has two ‘sources’ not one, 60 times per second. The third wire IS a ground but is not a “ground” (negative) in any fashion other than a path to the breaker in a fault. It cannot support service current because it is low impedance and trips the breaker or blows a fuse.

So both DC and AC grounds should be connected to the frame via an excellent clean electrical connection with wire rated at least as much as the electrical source wiring.
trying to understand the WHY and make sure it's safe and not just the standard way

Read the grounding paper.

Just DO NOT connect the Neutral and Ground/green/bare anywhere in the RV as it should be and is necessary to be bonded at the source of power- whether that be genset, shorepower, or onboard inverter but never at the same time.
 
Reread what I wrote and then look at the ‘grounding’ paper in the FAQ (resources section). You aren’t fully informed- yet. Not a criticism, just a fact.

DC systems should NEVER be anywhere near a neutral (AC systems have neutral, the 180* partner of the H/L1

no.
The ground in DC is both part of the load circuit and the ‘safety ground’ in a manner of speaking- but the actual safety is that IF the pos(+) contacts something else it shorts and trips the breaker or fuse. Because no matter what you think an unprotected DC circuit can cause a fire without blowing a fuse if not provided with that chassis bond; higher impedance current makes heat, heat makes fire.
Properly grounded the body/frame/chassis cannot be “energized.”

In an AC system, the current has two ‘sources’ not one, 60 times per second. The third wire IS a ground but is not a “ground” (negative) in any fashion other than a path to the breaker in a fault. It cannot support service current because it is low impedance and trips the breaker or blows a fuse.

So both DC and AC grounds should be connected to the frame via an excellent clean electrical connection with wire rated at least as much as the electrical source wiring.


Read the grounding paper.

Just DO NOT connect the Neutral and Ground/green/bare anywhere in the RV as it should be and is necessary to be bonded at the source of power- whether that be genset, shorepower, or onboard inverter but never at the same time.
I completely agree with everything you're saying. Thanks for the grounding paper, i'm assuming you mean this one https://diysolarforum.com/resources/grounding-made-simpler-part-4-mobile-systems.159/

Specifically on page 7:
There are several important grounding considerations when an inverter is added to the system.

AC Ground should be kept separate from DC ground and then tied together at a single point. However, in a simple system with the AC
sockets integrated into the inverter a separate AC ground bus may not be necessary.
1689175721734.png

The pic in the paper specifically doesn't show the AC being chassis grounded which contradicts yours and @timselectric comment if im reading right. I think you guys are saying it should be page 14 fig1
1689175697294.png

Isn't frame grounding causing a bunch of ground loops which are bad? Furthermore I have 4 AC electrical systems, the 20kw genset, the shore plug, the 12V inverter AC and the 48v inverter AC. If I don't frame ground the outlets, breaker panels and shore boxes everything will be grounded at the inverter only. My entire bottom half my bus is stainless steel, exterior sides, all bay sides and frame. Some places have wood or carpeting but not much which means my inverters are sitting and bolted into the frame along with my rack batteries and all paneling. I have to open stainless steel bay doors to get into my panels and physically lay or reach into solid metal boxes where i'll be the connection between frame ground and earth ground.

I'm not nearly as worried about ground loops (although i have a TON of radio and electrical systems, some very expensive) but the safety of people and mitigating electric shock risk
 
I really appreciate your help. I look at things differently and don't look at things the way we're told they're supposed to be or "recommended" but actually how they actually work and build the most efficient solution. Its why I have 2 separate inverter systems and 6 AC units that are different so I can maximize the efficiency of the resources.
 
Isn't frame grounding causing a bunch of ground loops which are bad?
No, it’s a single point. Two ends of a rope not touching. No loop
If I don't frame ground the outlets, breaker panels and shore boxes everything will be grounded at the inverter only
That is the way it should be- the source of power. As long as N and G never mix with the shorepower with N and G bonded. That’s part of what a transfer switch does. You have this wrong:
If I don't frame ground the outlets, breaker panels and shore boxes everything will be grounded at the inverter only
…unless the inverter is an AIO or hybrid that switches the bond depending on what function it is running in.

The generator should also not be bonded if bonded at the inverter (or main breaker panel).
 
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No, it’s a single point. Two ends of a rope not touching. No loop
I'm confused. in the images I posted from the pdf it shows there's a loop as the subpanel ground is touching the frame and also the inverter ground is touching the frame
 
I'm confused. in the images I posted from the pdf it shows there's a loop as the subpanel ground is touching the frame and also the inverter ground is touching the frame
If it is bonded (bonding generally referring to N-G) in only one place like it should be then there is no loop.
I did not review the drawing >sorry< but I’m assuming that the ‘loop’ is merely that the frame is being used as one big negative(-) and ground busbar. Which is acceptable for many but I never use frames, hulls, chassis, or body for a ground; I always merely connect a ground to it. I homerun all wiring. Sometimes a bit more money but usually not; however it never causes gremlins or mysteries.
 
If it is bonded (bonding generally referring to N-G) in only one place like it should be then there is no loop.
I did not review the drawing >sorry< but I’m assuming that the ‘loop’ is merely that the frame is being used as one big negative(-) and ground busbar. Which is acceptable for many but I never use frames, hulls, chassis, or body for a ground; I always merely connect a ground to it. I homerun all wiring. Sometimes a bit more money but usually not; however it never causes gremlins or mysteries.
I thought bonding is connecting any non current connections and grounding is physically grounding bonded wiring, but my terminology could be off.

Yes all wiring is homerun but when you purchase metal enclosures the ground connection is typically connected to the actual box itself, which in my case is going to be then connected to the metal frame of my coach creating a ton of these ground loops as well as it seems introducing additional shock risk for people
 
I thought bonding is connecting any non current connections and grounding is physically grounding bonded wiring, but my terminology could be off.
Nope
Colloquially ‘bonding’ is connecting two things but in the vernacular of residential and commercial electrical system installations it can be assumed generally that it refers to N-G bonding.
Neutral IS a current - carrying conductor. As is H,L1,L2,L3. Ground/green/bare is not.
Yes all wiring is homerun but when you purchase metal enclosures the ground connection is typically connected to the actual box itself,
On certain main panels, not others and usually not for subpanels ever.
which in my case is going to be then connected to the metal frame of my coach creating a ton of these ground loops as well as it seems introducing additional shock risk for people
No. It mitigates shock risk.
all wiring is homerun
Then even if installed wrong there can’t really be a LOOP
 
I'm just confused on how grounding to the frame makes it safer for people.
In the case of an RV, an ungrounded frame can pick up the potential of (say) a 120V line that comes in contact with the frame. That is dangerous, and you will see that potential if (for example) you step outside and touch the RV with your feet on dirt.

Say if my RV isnt connected to shore and on massive rubber tires. And say my floor is made of conductive stainless steel bonded to frame. Wouldn't I risk the ground becoming energized if frame was ground bonded?

Ok. So if your RV is not connected to ANYTHING and it is 100% isolated then most of this does not apply. As long as the standard neutral-ground bond is present (most inverters provide this) you are OK. That way if you are inside everything is referenced to the LOCAL ground and there is no hazard.
 
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