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I’m interested in this topic as well. I have a Firman h07553, and I confirmed it’s bonded at the engine by using a voltage meter (tested with the neutral attached and detached with generator off). My only concern is the issue mentioned regarding the bridge rectifier melting. Does anyone have more information on this?

I did reach out to support at Firman and they stated the mod isn’t supported based on warranty, NOT on the technical side. I also examined the schematic and it’s very similar as ones posted in this thread.

I also want to state, for clarity and not as a recommendation (or in regard to safety), that my setup with a ProTrans 2 into my main panel does work even though the generator has a bonded neutral, AND the main panel is bonded. There’s no issues with breakers flipping (this was a short test and only mentioned for completeness - do not take this as a recommendation for setup with considering local code).

I’d like to also state there is a lot of conflicting information online from Reliance, DYIers, electricians and everything in-between. Ranging from:
  • Bonded vs. floating is only an issue with GFCIs tripping.
  • Bonded vs. floating is a code and safety issue (being shocked or worst).
  • Bonded vs. floating is a non-issue because power is off at utility and it will prefer the path of least resistance.
A lot of this, I’m sure, is related to local code differences, interpretation differences, and just plain “it works for me, so it must be fine”.

I should also mention, with bias, that Reliance seemingly downplays any safety concerns and only mentions tripping breakers being a concern. Their “go to” solution is to simply disconnect the neutral at the generator and be done with it.
 

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Not sure if anyone has asked firman but worth the email.
I have 2 generators. A Northstar 13k and a pulsar 12k. Northstar wouldn’t provide any info on the alternator performance with the GN bond removed where as Pulsar quickly answered my email
And provided pics on which wire to remove. Worth seeing if you can find their contact info.
cheers.
 

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I’m interested in this topic as well. I have a Firman h07553, and I confirmed it’s bonded at the engine by using a voltage meter (tested with the neutral attached and detached with generator off). My only concern is the issue mentioned regarding the bridge rectifier melting. Does anyone have more information on this?

I did reach out to support at Firman and they stated the mod isn’t supported based on warranty, NOT on the technical side. I also examined the schematic and it’s very similar as ones posted in this thread.

I also want to state, for clarity and not as a recommendation (or in regard to safety), that my setup with a ProTrans 2 into my main panel does work even though the generator has a bonded neutral, AND the main panel is bonded. There’s no issues with breakers flipping (this was a short test and only mentioned for completeness - do not take this as a recommendation for setup with considering local code).

I’d like to also state there is a lot of conflicting information online from Reliance, DYIers, electricians and everything in-between. Ranging from:
  • Bonded vs. floating is only an issue with GFCIs tripping.
  • Bonded vs. floating is a code and safety issue (being shocked or worst).
  • Bonded vs. floating is a non-issue because power is off at utility and it will prefer the path of least resistance.
A lot of this, I’m sure, is related to local code differences, interpretation differences, and just plain “it works for me, so it must be fine”.

I should also mention, with bias, that Reliance seemingly downplays any safety concerns and only mentions tripping breakers being a concern. Their “go to” solution is to simply disconnect the neutral at the generator and be done with it.
I have a background in electrical engineering and I even find it daunting to get to a real practical answer.

Neither of my generators have a GFCI on the generator itself and I’ve never had a problem with Tripping GFCIs in the house so I was ignorantly bliss to the issue until I read the concern on a post here

Yes. Having only one GN bond in the system is code. But that code was changed so at some point it was acceptable to have more than one. From what I can see is at some point there must have been enough instances of people getting harmed that they changed the code. And for my money….I want to be code compliant so I’ve been searching for the right solution.

There are really 4 types of info im seeing from manufacturers.
1. Champion as an example. They post pics of how to float the neutral on specific generators they s
2 Others like pulsar will answer the question when asked and provide instructions
3 others refer you to a licensed electrician but I’m not certain how an electrician would
Answer a question like will removing the GN bond cause any alternator damage.
4 Others like Northstar who simply say they can not provide any detail.

I think I’m going to remove the bond on the Northstar and just run it in anger. Ultimately I’m more concerned about safety than damaging the unit and with no intel from the manufacturer it’s going to have to be a trial. And seeing as the bond is still in the system ( at the panel ) I’m thinking it’s a reasonable safe bet it works just fine. But will be making a jumper so if even run stand alone I can plug the jumper into an outlet on the generator and provide the GN bond through the panel.
Cheers
Mac
 

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My only concern is the issue mentioned regarding the bridge rectifier melting. Does anyone have more information on this?
So far there hasn't been a definitive response about this. I don't see how it could destroy the rectifier, but the schematic says it is an "intelligent" rectifier. It must be an electronic control rather than just a diode bridge. If, as posted, it destroys the rectifier by removing the N-G bond wire, then perhaps disconnecting the rectifier and using an external battery maintainer would bypass that issue.
I did reach out to support at Firman and they stated the mod isn’t supported based on warranty, NOT on the technical side.
Yeah, some manufacturers don't like to tell you how to modify the gen from the factory config so as not to incur liability. Other manufacturers freely tell you how to remove the N-G bond. Having more than one N-G bond in the system will result in current flowing on the safety ground wire. Current takes ALL paths back to the source, so there is no way to prevent current flowing on the ground wire if bonded at the house panel and the gen. Put the gen under an unbalanced load condition and then use a clamp-on meter to measure the current on the neutral and ground wires...they will be close to identical.
 

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I am going to attempt to reach out to Firman again, perhaps I'll reach someone else and get a better answer regarding lifting the neutral and how it affects the rectifier. I am going to also try to get a specific part number of the rectifier, and perhaps find more information about it online (being "intelligent" as GenKnot mentions vs. a diode bridge).

I am also curious now based on macdenewf's comment of when and why the code was changed, but I agree safety first.
 

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This is interesting. Based on the comments from the author of the video he had no issues with his bridge rectifier and it’s the same model referenced earlier in this thread. I wonder what the difference is?

My Firman h07553 looks exactly the same on the generator motor (also of note, the white short cable can be removed entirely if desired).
 

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I am also curious now based on macdenewf's comment of when and why the code was changed
He is possibly referring to the change made in NEC 2008 pertaining to the acceptable grounding methods at buildings or structures supplied by a feeder or branch circuits from a grounded service located at another building or structure supplied from a common service. A subpanel is an example...you do not make a N-G bond there so as to avoid objectionable current on the ground wire.
 

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This is interesting. Based on the comments from the author of the video he had no issues with his bridge rectifier and it’s the same model referenced earlier in this thread. I wonder what the difference is?

My Firman h07553 looks exactly the same on the generator motor (also of note, the white short cable can be removed entirely if desired).
I called Firman but got a same response on N-G bond like others. They do not recommend it but at the same time, they can not (or won’t) say what impact it may have. I wish they had clear steps like Champion to remove N-G bond. The jumper and schematic has no big difference and it is super simple to remove N-G bond.

i also asked them directly on the functionality of that intelligent rectifier and what will happen if I unplug the rectifier, the person I was talking to did not seem too technical and simply said “it needs to be there for the generator to function correctly”.
 

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I hadn't noticed until now that a photo of the rectifier was uploaded by DL41 in post #15. It is indeed a circuit board in lieu of just a bridge rectifier. That probably explains the "intelligent" name it is given on the schematic. It still doesn't explain why disconnecting the N-G bond on the gen would harm it.

The Brown wires are AC input, Green/Yellow is -, and then Red is + output.
Circuit component Networking cables Computer hardware Electrical wiring Electronic component

simply said “it needs to be there for the generator to function correctly”.
Well, that's not exactly a wrong answer as the battery will run down without some manner of recharging it. But, of course, your question was about what happens to the rectifier if the N-G bond is removed.
 

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He is possibly referring to the change made in NEC 2008 pertaining to the acceptable grounding methods at buildings or structures supplied by a feeder or branch circuits from a grounded service located at another building or structure supplied from a common service. A subpanel is an example...you do not make a N-G bond there so as to avoid objectionable current on the ground wire.
Correct. I actually though the nec change on single GN bonds was 1999 though. But not a code expert.
I do have a floating neutral gen and a grounded neutral. I’m going to connect them both up and truly see if I can detect current on the ground.
 

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I'm willing to bet that "intelligent" bridge rectifier is just a fancy name for a voltage regulator. It basically charges the battery and supplies power to the fuel cut solenoid (when triggered), as well as the generator control box/module.

I can't imagine a scenario wherein removing the N-G bond could have an effect on this regulator, much less destroy it. The DC ground path should still work in this case, regardless of whether or not it's tied in to the Neutral circuit. The only reason it can burn up is if a voltage differential is introduced as a result of removing the bond. But again, I don't see how that's possible.
 

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I hadn't noticed until now that a photo of the rectifier was uploaded by DL41 in post #15. It is indeed a circuit board in lieu of just a bridge rectifier. That probably explains the "intelligent" name it is given on the schematic. It still doesn't explain why disconnecting the N-G bond on the gen would harm it.

The Brown wires are AC input, Green/Yellow is -, and then Red is + output.
View attachment 12206

Well, that's not exactly a wrong answer as the battery will run down without some manner of recharging it. But, of course, your question was about what happens to the rectifier if the N-G bond is removed.
I left a comment on the Youtube video posted earlier, hoping the owner will respond to see if his bridge rectifier still doesn't have issues. I am wondering if DL41's was a weird fluke?

This is off-topic from the N-G bond discussion, but worth noting for others who may find this thread trying to setup a portable generator for whole-house emergency backup power. Be sure to adjust the governor on the motor itself to set the appropriate frequency to help minimize issues (on my Firman it's a silver screw near the governor spring loaded arm). I checked mine running idle and then under load. These Firman's have a high THD, so it's more of a "set it the best you can". The Firman's have a digital readout to check frequency, other generators may require a tool.
 

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With the risk of destroying the generator and voiding my warranty being too much, I've decided to look into an Inverter Generator that will provide sufficient power (to avoid THD issues) along with allowing the neutral to be floating. For those of you who may find this thread in the future this is what I am considering at the moment:


Champion has support with videos for lifting the neutral bond (very simple), the THD is low, run-time is decent, it has a 50A hookup (which I need), it's quieter and price point isn't too much more.
 

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👆 Sounds like a good plan to me.

I have an older Champion (2008 model) non-inverter that has served me well. I recently bought a WEN GN625i that is an inverter unit. The waveforms on it are better looking than my grid power...I'm very happy with it. I had to change to the WEN because my old Champion had too much THD to run my new gas furnace blower. The Champion inverter should have a comparable high-quality sinewave too.
 

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I'm monitoring this thread regarding the issue of converting a Firman generator, T08072 in my case, from bonded to floating neutral. My setup is a manual interlock switch on my panel, and a 50amp plug for connection to the generator.
Initial testing works well on natural gas, which I plan to use for partial home backup. I like the option of a manual transfer switch and I pick which circuits/devices I want.
I would like to have the safest setup possible, so a single bonded connection in the main panel and a floating neutral at the generator is the setup as I understand it.
My son-in-law, an electrician, installed my 50amp setup and confirmed there should be only one neutral ground point, and should be at the main panel. He really could not comment on the Firman generator changing to floating neutral causing any damage in the generator.
Hearing from a few users that they have made the change to the Firman generator with no damage to the regulator would be welcome.
 

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Hearing from a few users that they have made the change to the Firman generator with no damage to the regulator would be welcome.
Yes, it would be good to hear that the N-G bond can be disconnected without frying the voltage regulator on the unit. Unfortunately, no one has said that is the case. So, the jury is still out!
 

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Look in your Owner's Manual at the wiring diagram (page 37, I believe). Near the AVR there is a jumper that's tying the Neutral to the Ground. Remove it and you've floated the neutral. I've circled the jumper in red below.
View attachment 9811
It probably looks something like this:
View attachment 9812
I just disconnected the Neutral from ground as per tabora.
Works great - no overheating/smoke from Bridge Rectifier. Charging battery.
So far all is good.
Bob
 

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I just disconnected the Neutral from ground as per tabora.
Works great - no overheating/smoke from Bridge Rectifier. Charging battery.
So far all is good.
Thanks for that feedback!
NOTHING should happen to the rectifier (aka voltage regulator) as a result of floating the neutral based upon examining the schematic.
It does not explain what happened to DL41's gen because he smoked his voltage regulator assembly. It could be that his unit has an unknown wiring error somewhere. Who knows?!
 
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