[MetaCipher]

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

Good to know! I would also add that the author of this video here (Remove Neutral from Frame Firman T07571) states he still has no issues, but he plans to test further.

For me personally, I did decide to go with the Champion unit above.

 

[OrlyP]

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?!

Or the cause was totally unrelated and it was just a coincidence that the last thing he did was to remove the N-G bond when it happened.

 

[GenKnot]

But he did it at least twice. See post #15.

 

[Arc41]

Was the generator running off line or connected to a home in which case the neutral ground connection would be restored. Still very confusing I have remove the link on mine but have yet to see how the voltage regulator reacts to this new configuration/

 

[GenKnot]

Was the generator running off line or connected to a home in which case the neutral ground connection would be restored. Still very confusing I have remove the link on mine but have yet to see how the voltage regulator reacts to this new configuration/

The N-G bond connection will not affect the output voltage or frequency if that is what you are wondering about.

 

[Arc41]

No I was concerned that the voltage regulator or rectifier would overheat without the neutral/ground link either through the hardwired link or through the service connection, which seemed to be the result in previous posts.

 

[GenKnot]

No I was concerned that the voltage regulator or rectifier would overheat without the neutral/ground link either through the hardwired link or through the service connection, which seemed to be the result in previous posts.

Oh, okay. Fortunately, only one person has reported an issue with that happening. I think it must be an anomaly with DL41's gen.

 

[Arc41]

Yes hope that's the case will give it a try. It's a holiday here in Canada today so will wait until less activity.

 

[Gus01]

I recently purchased a Firman T07571 Tri-fuel 7500/9400 watt generator from Costco.

I also installed a Square D by Schneider Electric QO1DM10030TRBR 30-Amp Generator Main Breaker Outdoor Manual Transfer Switch.

I intend to use the generator strictly as a back-up power supply for my home and will not use it like a construction site generator.

The Square D generator transfer switch panel uses the main service panel neutral.

The owner's manual for the Firman generator states that the neutral is bonded to the frame.

I understand that the neutral cannot be grounded in two places and that I need to disconnect the neutral from the generator's frame.

My question is: What is the procedure for disconnecting the neutral from the frame for this Firman generator?

I contacted Firman with this question, but they have not yet responded.

Thanks for all replies.

Hi
I have the same situation as yours powering my house as a backup thru a Siemens Generator sub panel. Did you figure out how to convert the Firman T07571 generator to floating neutral? What about the rest of the discussion about it overheating the rectifier when this is done?
Thanks
Gus

 

[GenKnot]

Did you figure out how to convert the Firman T07571 generator to floating neutral? What about the rest of the discussion about it overheating the rectifier when this is done?

What more can be said about those two things that hasn't already been answered in the thread? Did you read the entire thread?

 

[Columbotrek]

This thread addresses the rectifier issue pretty well. My takeaway is if the ground neutral bond is disconnected, do not start this generator without either being connected to the house service panel or making the use of a neutral to ground bonding plug in one of the generators unused outlets. Either would restore the N/G connection and the Generator could then be safely run. As to why the smart rectifier burned up, could it be the designer was relying on the chassis to provide a path to the neutral for a reference thus saving the use of a wire?

 

[GenKnot]

Apparently, nothing bad will happen to the rectifier if the N-G bond is removed as reported by the user in post #59. Also, the author of the referenced video below didn't report any issues either. The situation with DL41 must be an anomaly.

How to remove the N-G bond...

Remove Neutral from Frame Firman T07571

www.youtube.com

 

[Arc41]

Now have another problem with my Firman tri fuel gen it will not start on NG. Red light comes on but not starting. I checked the gas shut off solenoid and there is no power to it, assume it should be powered when LPG or NG is selected ...any thoughts

 

[Aventinus]

I believe the better approach to this problem is to continue using a four connector cable from the generator to the inlet box on the house, and using the generator ground to ground out the inlet box only. That said I would leave the ground connector of the cable from your breaker box to the inlet box floating. This will provide fault safety for the inlet box, and by not connecting the breaker panel ground to the inlet box or generator ground, you will maintain a single ground in the system and still be protected by the always connected neutral and the single existing house ground. Yes this will be a longer path, but you'll still have only one single path for fault protection which is important. Having multiple grounds and paths through other wiring schemes can create what are called Ground Loop currents and can present noise and other issues for devices in the home. This approach also has the side benefit of maintaining the safety Integrity of the generator in the rear event you decide to use it with an extension cord to do something on the outside of your home or property.

 

[GenKnot]

I believe the better approach to this problem is to continue using a four connector cable from the generator to the inlet box on the house, and using the generator ground to ground out the inlet box only. That said I would leave the ground connector of the cable from your breaker box to the inlet box floating.

Wouldn't meet code for Not a Separately Derived System. The grounding conductor must be continuous from the source (the gen) to the house loads.

 

[Ida]

1--In regards to posts #2 and #4, where the ground wire in the cord is basically removed, and you use this short, 1 foot, modified cord between the generator and the main cord. What are the thoughts on the merit of this solution? Seems simple. Is it safe and effective?
2--In regards to the instances of the rectifier smoking/melting: does this happen in a minute, an hour, many hours?
3--On my new Firman T07573, there is a yellow wire with a green stripe screwed on the bottom of the metal frame of the engine, and it is connected to the bottom crossmember of the frame of the generator. It is wide open exposed, and there is nothing else connected to it. Is this a ground wire? If so, it would be extremely easy to disconnect.

 

[GenKnot]

1--In regards to posts #2 and #4, where the ground wire in the cord is basically removed, and you use this short, 1 foot, modified cord between the generator and the main cord. What are the thoughts on the merit of this solution? Seems simple. Is it safe and effective?

It is best to use a bonding plug if you want the ability to easily reconnect the N-G bond if you need to do so temporarily. Search Google for "generator bonding plug" and look at the images. You can buy them premade, or make your own by just connecting neutral and ground in plug.

2--In regards to the instances of the rectifier smoking/melting: does this happen in a minute, an hour, many hours?

It apparently does not happen.

3--On my new Firman T07573, there is a yellow wire with a green stripe screwed on the bottom of the metal frame of the engine, and it is connected to the bottom crossmember of the frame of the generator. It is wide open exposed, and there is nothing else connected to it. Is this a ground wire? If so, it would be extremely easy to disconnect

That is frame to alternator bond. Do not remove it. It is not the N-G bond.

 

[GenKnot]

One more thought about your first question...
Do not use a cord with the ground disconnected/removed. If you do not want/need the N-G bond connected, then disconnect it properly at the gen.

 

[Ida]

Thanks for your responses.
I understand (I think) how to disconnect the white wire at the back of the motor to un-bond the generator, but I was pausing at this due to issues I've read about voiding warranties, melting rectifiers (possibly), Firman saying not to do it, etc.
Would the bonding plug work, without the above concerns? If so, that sounds like the easiest, most easily reversible solution.
So, to make a bonding plug, you just get a 30 amp 4 blade twist lock plug, and connect the neutral wire and the ground wire to the same terminal? Ground = green; and neutral = white, on the same screw in the plug?

 

[GenKnot]

I understand (I think) how to disconnect the white wire at the back of the motor to un-bond the generator, but I was pausing at this due to issues I've read about voiding warranties, melting rectifiers (possibly), Firman saying not to do it, etc.
Would the bonding plug work, without the above concerns? If so, that sounds like the easiest, most easily reversible solution.

Only one person (DL41) reported an issue with his rectifier burning up. The others that have removed the N-G bond at the gen have not reported the same results. There seems to be something wrong with DL41's gen that is causing this. As for Firman saying not to remove the bond, I would take that with a grain of salt. A lot of the manufacturers don't want to tell you how to modify their gens from the factory configuration while other manufacturers freely tell you how to remove the N-G bond. Champion is an example of a manufacturer that tells you how to remove the N-G bond to modify the gen to a floating configuration...

Disconnecting the Neutral Bond to Frame

For certain generator applications, a qualified electrician may recommend removing the neutral bond to the generator frame, resulting in a "floating neutral." Feeding electrical power to a house thro…

help.championpowerequipment.com

A bonding plug is used by many portable generator users to reestablish the N-G bond when using the gen not connected to the house. This puts the gen back into the factory bonded condition. When the gen is connected to the house, the N-G bond is established at the house breaker panel. You would not use the bonding plug when the gen is connected to the house.

So, to make a bonding plug, you just get a 30 amp 4 blade twist lock plug, and connect the neutral wire and the ground wire to the same terminal? Ground = green; and neutral = white, on the same screw in the plug?

You can do it with either a twist lock plug or just a standard 120V plug. You would jumper ground over to neutral...no other wires connected.
With the cover off, it would look something like this...