Generator neutral-ground bonding

[rohrmann]

Actually, there is already a difference of potential between the energized line and the helicopter. The electric field can cause bad burns, and that is why the lineman wears a Faraday suit to protect against the electric field. The bond is made with a jumper between the helicopter and the line so the lineman isn't the jumper when he makes contact. Watch this video and see the arc made when he makes the connection and also when he disconnects the wand.

https://www.youtube.com/watch?v=DPNK7bc2qvM

[BB_TX]

Have to admire those guys, both the pilot and the guy hanging out there.

[steiny93]

Here is a really simplified article, great read on the topic: https://www.rvtravel.com/rv-electric...ng_generators/

[Backoffg]

Neutral and Ground should only be Bonded at the Main Disconnect. Surge protectors will generally disabled or trip when detecting voltage above 1.5 volt on the Neutral or Ground .The common cause for this is when the Neutral and the Ground are improperly Bonded or Bonded in between the main Disconnect.

[firestation12]

Originally Posted by BB_TX

And that was a large part of the discussion. But for there to be a difference between the amount of current flowing in the hot pin and the amount of current flowing back out the neutral pin requires that the difference has to have “leaked” out of the circuit between the two. But current can’t leak out without a path back to the source, in this case the generator. And with no ground there is no path for that errant ground fault current to get back. So a difference can’t exist. Current must have a closed path back to the initial source to flow.

I’ve read this post several times in an effort to fully understand the terminology BB_TX is using or how the point being made is valid. For starters, I disagree with the above quoted statement in it’s totality. There seems to be a misunderstanding of the function of a GFCI and a circuit breaker. Current can “leak out” of a hot conductor without a return pathway to the generator, shore power, or whatever source. Overcurrent devices (breakers), AFCIs and GFCI’s handle dangerous electrical voltage in several different but key ways. Circuit breakers can be manufactured to perform more than one function i.e. open a circuit instantaneously in the case of a direct short circuit, open when current flow would cause wiring to overheat over time, open a circuit with the presence of arcing, and opening a circuit with detection of minute current losses capable of producing death but not enough to open a circuit with a full short to neutral or ground. Single purpose protection devices are found in our campers… GFCIs and circuit breakers. Circuit beakers require a clear pathway back to the neutral or ground to perform their intended function. A GFCI does not. I’m in agreement with post #5, i.e. a GFCI operates properly with or without a ground. It only monitors the relationship of the hot to neutral. Any discrepancy between the two causes a trip. Remove the ground wire from the GFCI and it still functions normally. The GFCI has no idea from what source power is being supplied… generator (with or without a neutral/ground jumper), shore power or inverter. The use of GFCI circuit breakers has long been a workaround fix for older homes that lacked grounded receptacles. The inexpensive 3 light (2 yellow and one red) plug in GFCI tester that many of those here on the forum have and use, DOES rely on a properly grounded GFCI outlet to create a leak pathway when the test button is pushed. IF…. a generator were to incorporate a GFCI as its primary source to an un-bonded camper, the GFCI would trip when the “hot” skin was touched whether or not the generator was bonded to the camper frame. The ground wire on the GFCI is there simply to provide a pathway for the circuit breaker to trip. GFCI outlets do not provide short circuit protection.

[dfb]

A power source or any device that can cause human shock, ie a cable or a landline phone MUST BE GROUNDED to prevent severe injury or death. Im guilty myself. A good ground goes the the Earth. Ground is ground the world around. A ground provides a path for current to go which is back to the dirt .Believe me,, you do not want to be ground or the path for current to go if it's needed to. In electronics a ground will make them stable. Without it a hum can occur or unstable electronics operation. WHEN USING A PORTABLE genset, it is strongly advised to pound a grounding rod into the dirt. Then find a clean metal part on the frame to connect the ground wire to.

[BB_TX]

Originally Posted by firestation12

I’ve read this post several times in an effort to fully understand the terminology BB_TX is using or how the point being made is valid. For starters, I disagree with the above quoted statement in it’s totality. There seems to be a misunderstanding of the function of a GFCI and a circuit breaker. Current can “leak out” of a hot conductor without a return pathway to the generator, shore power, or whatever source. ………….

A very basic principle of electricity is that there must be a closed circuit to provide a path for current (electrons) to flow from the positive terminal of the power source to the negative terminal of that same power source. What goes out comes back in. Those electrons can not “leak” out without a path back to that power source. That defies that basic principle. You feel otherwise so please show me some technical source that validates your statement that it is possible. I would really like to know if that is in fact possible.

And yes I fully understand GFCI outlet. Yes, a GFCI outlet with no ground will supply power to the appliance plugged into it. No, the GFCI will not trip on a ground fault without some path back to the power source for the leakage current to travel to create the necessary imbalance. Those electrons can not leak into thin air.

NEC permits the use of GFCIs in older homes with no ground wiring. GFCIs are required in areas that may be exposed to wet conditions such as around sinks and faucets. Water in older homes comes from buried pipes. Pipes buried in the ground become earth ground just as a ground rod driven into the ground would. This provides the return path for a GFCI in an older home with no wired ground to trip on a ground fault.

[firestation12]

Originally Posted by dfb

A power source or any device that can cause human shock, ie a cable or a landline phone MUST BE GROUNDED to prevent severe injury or death. Im guilty myself. A good ground goes the the Earth. Ground is ground the world around. A ground provides a path for current to go which is back to the dirt .Believe me,, you do not want to be ground or the path for current to go if it's needed to. In electronics a ground will make them stable. Without it a hum can occur or unstable electronics operation. WHEN USING A PORTABLE genset, it is strongly advised to pound a grounding rod into the dirt. Then find a clean metal part on the frame to connect the ground wire to.

You are preaching to the choir. Not saying appliances shouldn’t be grounded. Not saying the GFCI shouldn’t have a ground wire attached. It should! A ground wire is necessary so the upstream circuit breaker can perform overcurrent protection. A GFCI is NOT for current overload protection. I simply stated that the way a GFCI provides protection is separate and apart from the circuit breaker.

[mlh]

This is a great discussion,,, for me. I’ve been working on my old home place this summer with the help of family. It needs heating and air conditioning but without a three wire system I was sure I couldn’t get them because I needed at least 200 amp service when we only had 60 amp service and it would haft to pass code. The 2 wire may pass if we install GFCI on each circuit. Maybe there is a way around this IF I have enough money left. We are going to let my great nephew live in it almost free but what are families for.
Lynwood

[BB_TX]

Lynwood - you would have to check your AHJ (authority having jurisdiction) to see if you could upgrade your distribution panel to 200 amp without adding grounding throughout. Not sure they would approve that.

[dfb]

When I took electronics the energy flow was from negative to positive in a battery circuit or dc..

[BB_TX]

Originally Posted by dfb

When I took electronics the energy flow was from negative to positive in a battery circuit or dc..

Yeah, that is true. There is “conventional” current theory. That stems from the belief that current flowed from positive to negative during the early days of electrical development. It was later learned that electrons actually flow from negative to positive.

Negative means there is an excess of normally neutral atoms having extra electrons giving that atom a negative charge (electrons have a negative charge). Positive means there is an excess of normally neutral atoms that are missing an electron giving that atom a positive charge (described as having an empty orbit or “hole”). Since positives attract negatives, when positive is connected to negative the excess electrons race from negative to positive to fill those “holes”. So conventional current is sometimes called “hole flow”, opposite of electron flow. But to keep things simple and avoid confusion (which I just did ) current is still generally thought of as “conventional” and flowing from positive to negative.

Wow! I still remember all that after 50+ years. But we are getting pretty deep now.

[Lee-CI]

Attempting to convince folks that DC current flows from negative to positive as can be proven at the sub atomic level is just as fun as explaining that 120 VAC circuits as measured by a RMS multimeter is actually 339.4 volts peak to peak.

[rohrmann]

Originally Posted by dfb

A power source or any device that can cause human shock, ie a cable or a landline phone MUST BE GROUNDED to prevent severe injury or death. Im guilty myself. A good ground goes the the Earth. Ground is ground the world around. A ground provides a path for current to go which is back to the dirt .Believe me,, you do not want to be ground or the path for current to go if it's needed to. In electronics a ground will make them stable. Without it a hum can occur or unstable electronics operation. WHEN USING A PORTABLE genset, it is strongly advised to pound a grounding rod into the dirt. Then find a clean metal part on the frame to connect the ground wire to.

Unless you are going to call for a locate prior to driving that ground rod and then willing to drive an 8 ft rod to obtain a sufficient ground, and then doing this every time to set up your generator, this is not going to provide a ground that will do what you are wanting. I have personally seen what driving a ground rod into a high voltage underground cable can do.

[LeftOverParts]

We carry two portable, 2000 watt Champion gens just in case. They have a ground terminal and the instructions say to ground it.

FWIW, this OSHA link states when a portable gen should be grounded.

https://www.osha.gov/sites/default/f..._generator.pdf

[BB_TX]

Originally Posted by Lee-CI

Attempting to convince folks that DC current flows from negative to positive as can be proven at the sub atomic level is just as fun as explaining that 120 VAC circuits as measured by a RMS multimeter is actually 339.4 volts peak to peak.

Most people don’t really care HOW something works. Only that it DOES work. I am one of those exceptions that want to know how and why something works. And if it doesn’t, can I fix it. I see it as a challenge. Goes all the way back to childhood when I would find a discarded item that didn’t work and then take it apart to see if I could repair it, or at least understand it. But that lifelong curiosity is the reason there are not many things I cannot make a generally successful attempt to self repair whether electrical, mechanical, plumbing, woodworking, auto, etc. And has saved me a ton of money.

[firestation12]

Originally Posted by BB_TX

A very basic principle of electricity is that there must be a closed circuit to provide a path for current (electrons) to flow from the positive terminal of the power source to the negative terminal of that same power source. What goes out comes back in. Those electrons can not “leak” out without a path back to that power source. That defies that basic principle. You feel otherwise so please show me some technical source that validates your statement that it is possible. I would really like to know if that is in fact possible.

And yes I fully understand GFCI outlet. Yes, a GFCI outlet with no ground will supply power to the appliance plugged into it. No, the GFCI will not trip on a ground fault without some path back to the power source for the leakage current to travel to create the necessary imbalance. Those electrons can not leak into thin air.

NEC permits the use of GFCIs in older homes with no ground wiring. GFCIs are required in areas that may be exposed to wet conditions such as around sinks and faucets. Water in older homes comes from buried pipes. Pipes buried in the ground become earth ground just as a ground rod driven into the ground would. This provides the return path for a GFCI in an older home with no wired ground to trip on a ground fault.

A GFCI certainly will perform its intended function without a grounding conductor attached. It needs only a hot and neutral to function. Perform a search, “will a GFCI trip without a ground?”. I did love the hokey explanation how old galvanized piping is what allows a GFCI without a ground to function. You probably are not aware that that a circuit breaker style GFCI will trip even if the neutral is lost somewhere between a downstream outlet and the panel. Why? The small curly white pigtail of the CFCI circuit breaker is the source of monitoring the imbalance of the hot and neutral. Of course nothing plugged into the outlet will work, but the shock protection is still functional. Here’s another statement that befuddles,
“Those electrons can not “leak” out without a path back to that power source. That defies that basic principle”. A current leakage can occur anyplace a grounding fault takes place. You seem to imply there has to be a dedicated pathway going directly to the power source for a leak to occur. Am I mis-quoting you? As for your request to provide any sources to validate my claim, I’d prefer you validate my claim. Place a generator on an isolating surface, start it, remove shoes, insert a screw driver firmly into the smaller vertical opening of a receptacle, finally without touching the generator grab the bare metal screw driver shaft. Report back if a dedicated path back to the generator (power source) is necessary for a leak to occur. Lastly I’ll pass on the discussion of positive/negative poles on alternating current. I’ve been unable find a way to make my Fieldpiece meter show that, when I switch the probes between hot and neutral wires. I hesitate to use the DC setting to see if that can sense pos/neg.

[rohrmann]

Originally Posted by LeftOverParts

We carry two portable, 2000 watt Champion gens just in case. They have a ground terminal and the instructions say to ground it.

FWIW, this OSHA link states when a portable gen should be grounded.

https://www.osha.gov/sites/default/f..._generator.pdf

I guess you didn't read the part that says:


Under the following conditions, OSHA
directs (29 CFR 1926.404(f)(3)(i)) that the
frame of a portable generator need not be
grounded (connected to earth) and that the
frame may serve as the ground (in place of
the earth):



The generator supplies only equipment
mounted on the generator and/or cord and
plug-connected equipment through
receptacles mounted on the generator


Thus, rather than connect to a grounding
electrode system, such as a driven ground
rod, the generator’s frame replaces the
grounding electrode


Hopefully, you aren't hardwiring your portable generator to your RV, but are using a cord and plug to make the connection. Also, do rigs that have a permanently installed generator have to drive a ground rod when they run their generator? Pretty sure they aren't governed by OSHA. I know I don't have to abide by OSHA rules anymore.


And, thank you for the link to the OSHA FACT SHEET. This helps when those concerned about if they need to drive ground rods need answers.

[BB_TX]

Originally Posted by firestation12

…….

“Those electrons can not “leak” out without a path back to that power source. That defies that basic principle”. A current leakage can occur anyplace a grounding fault takes place. You seem to imply there has to be a dedicated pathway going directly to the power source for a leak to occur. Am I mis-quoting you? As for your request to provide any sources to validate my claim, I’d prefer you validate my claim. ….

I can provide you any number of technical links about electric current requiring a closed loop back to source to provide a path for flow. And, that current will not flow in an open circuit. Apparently you can not provide a link to support your position that those electrons can leak out to no where. Not my job to validate your claims.

We will leave it at that.

[firestation12]

Originally Posted by rohrmann

I guess you didn't read the part that says:


Under the following conditions, OSHA
directs (29 CFR 1926.404(f)(3)(i)) that the
frame of a portable generator need not be
grounded (connected to earth) and that the
frame may serve as the ground (in place of
the earth):



The generator supplies only equipment
mounted on the generator and/or cord and
plug-connected equipment through
receptacles mounted on the generator


Thus, rather than connect to a grounding
electrode system, such as a driven ground
rod, the generator’s frame replaces the
grounding electrode


Hopefully, you aren't hardwiring your portable generator to your RV, but are using a cord and plug to make the connection. Also, do rigs that have a permanently installed generator have to drive a ground rod when they run their generator? Pretty sure they aren't governed by OSHA. I know I don't have to abide by OSHA rules anymore.


And, thank you for the link to the OSHA FACT SHEET. This helps when those concerned about if they need to drive ground rods need answers.

Rohrmann, your former expertise is always so spot on. I’m wondering if there has been some confusion in this entire thread between a permanently installed generator and a portable generator in terms of which are being regulated under the NEC relative to RVs. I seem to remember from past rules, that the service entrance section for structures is allowed to have the ground and neutral bonded, but any subsequent sub panels fed from the ses must have isolated grounds. Is that your understanding? If that were the case, would the permanently mounted generator be considered the first point as the power source where the neutral ground bond is allowed? Second question- when the transfer switch disconnects shore power’s hots and neutral from the camper and engages the on board generator, does the generator become the defacto primary source? Apologies in advance for sucking you back into this thread. John