Generator Should I change my PTO generator from Bonded Neutral to Floating Neutral?

[DarkBlack]

I hang my head and try to say this again for all to listen or ignore (Jpc gets it ) If you disconect the neutral to ground jumper on the jenny.... You loose the ground conductor from the genny to the house during a fault. QUOTE]

I don't think that is so, the neutral (aka "grounded conductor) and the (equipment) grounding conductor are bonded at the house panel, the fault current will re-enter the neutral back to the jenny's winding here.

I said you loose the ground (grounding) conductor. I didn't say you loose the grounded conductor.

 

[joshuabardwell]

This helped a few things fall into place for me that, no matter how many times I had heard them explained, I just couldn't get to "click". Thanks.

Wouldn't this just trip its own breaker in the box? : Only if the fault current is big enough to trip the breaker. To put it another way: Only if there is a path of low (enough) resistance back to the center tap (neutral) connection of a transformers or generator's winding, thus the circuit's loop is completed and current will be high enough that the breaker will trip. The "best fault" situation is when the fault is to something that has a grounding (green) conductor attached to it, then there's a low resistance path back to the neutral of the generator (because the grounding system and neutral are bonded in your house panel).
If there's a fault to something not "grounded" well enough that the breaker doesn't trip, then that object will become energized, and a person who touches it may become the path of least resistance.

Without a grounding (green) conductor to take the fault current back to the winding (in a "short" circuit), one is relying on earth as part of the circuit's loop back to the winding. (a "long circuit" ? that is, the path would be from that shorted object in contact with the ground, throught the ground, into the ground rod, to the neutral bonded to the ground in your panel, back to the generator's winding neutral tap. Here, the ground (earth) is not a good conductor, and the fault current in this scenario may not be enough to trip the breaker.

A couple things about grounding that most people don't realize: 1. The biggest function of a ground rod on a electrical service is to provide a 0 volt reference (period). A gound rod's function is not "to send fault current into the ground" (except for lightning strikes I suppose, but I digress) 2. The point of grounding (green) conductors connected to equipment is not to send fault current to the ground rod/earth, it is to have a low resistance path (i.e. a "short" circuit) to the neutral winding of the power source (transformer or generator) during a fault. Low resistance = high current = tripping breaker/fuse. That is why the neutral and grounding conductor is bonded in the panel. 3. The reason they are bonded in only one place so that normal neutral current does not have a parallel path on the green grounding conductor, otherwise normal neutral current (times any resistance) would = a voltage (Ohm's Law) on the various normally non-current carrying metal parts that are connected to the (green wired) grounding system.

 

[TMB1320]

Floating neutral eh? Not really genny related, but it happened, so I'll tell it.
Ten years ago the power company were changing poles and in so doing rerouted
the above ground feed (2 insulated conductors around an uninsulated carrier conductor.
The reroute was through a thicket of cedar trees.
Two years ago the uninsulated conductor had completely disconnected by a constant
rub that a cedar tree had managed to rug off. Now that is a floating neutral.
The floating neutral voltage to either 120v was totally dependent on the loads
I measured it at 180v-60v. No 240 volt appliance were affected, but it blew th snot out
of the surge protector and fuse of the old built in above stove microwave, and a stereo receiver.
The ballast on the floresent fixture in the laundry room got smoked also..
The nuke runs 'till this day, sans surge protection.

 

[Victory Pete]

Floating neutral eh? Not really genny related, but it happened, so I'll tell it.
Ten years ago the power company were changing poles and in so doing rerouted
the above ground feed (2 insulated conductors around an uninsulated carrier conductor.
The reroute was through a thicket of cedar trees.
Two years ago the uninsulated conductor had completely disconnected by a constant
rub that a cedar tree had managed to rug off. Now that is a floating neutral.
The floating neutral voltage to either 120v was totally dependent on the loads
I measured it at 180v-60v. No 240 volt appliance were affected, but it blew th snot out
of the surge protector and fuse of the old built in above stove microwave, and a stereo receiver.
The ballast on the floresent fixture in the laundry room got smoked also..
The nuke runs 'till this day, sans surge protection.

Happens all the time. The neutral tap is the worst one to lose. A surge protector caught fire once from getting the overvoltage.

VP

 

[stonypass]

PTO Generator Now Wired and Tested

After much consideration, I modified the generator to have a Floating Neutral and made up a plug that Bonds Neutral to Ground for standalone usage.

A clamp-on meter from HF was used to test current draw on all my high usage items so I would know what combinations I am able to use with the genset at the same time.
I also mounted a remote 120v outlet on the front of my TSC carry-all for a Kill-A-Watt that can be seen from the tractor seat (or from the ground) for properly setting frequency.
An outlet tester shows proper configuration at 120v outlets in the home when the genset is connected and running, and the generator shows the same in standalone mode when using the bonding plug.

Yesterday I did a full test of the Generator and ran everything in the house, setting the frequency at 62hz with no load and then testing first lights, high usage items then electronics.
My high usage items are a 1.5hp 650ft well pump, electric dryer, range/stove, and a 4 ton central A/C unit.
The generator had no problems with any of these and will easily run the well pump with any other single high usage item along with lights, refrigerator/freezer, TV/Satellite and PC/Internet.
The Kubota has plenty of power with 37 PTO hp and I never saw lights flicker, the rpm vary much or the frequency go below 60hz under the highest loads.

This setup may not suit everyone but will provide emergency power to anywhere in my home and barn which is what I was after.
Thanks to all who responded, your advice was appreciated.

I would like to add a pilot light to the breaker box to tell me when grid power has been restored, if someone can point me to a link for a suitable Neon or LED light and holder that can be hooked to one side of my input power I would appreciate it.

 

[Qapla]

Qapla: ...You really have three panels????

Yes, I really have three panels.

1) This is the main panel where the meter is on the pole. It used to feed the MH we had install and had a 150 AMP Breaker feeding the MH. When we upgraded to a new MH, the old home was still in place as we were still living in it. This required that we set the new house in a different spot behind the old house. Since we were still going to be using the same power pole and septic system, the new house was positioned at a right angle to the old house just behind the old house and septic tank.

The new house location made it more then 30' from the pole and, according to local code, this required we have a disconnect at the end of the new house. Since the existing power service was wired for 250 AMP service no changes needed to be made to the service pole I just had to install a 200 AMP breaker to feed the new house.

2) We have a panel at the end of the house. This panel was required to be mounted on its own support since local code would not allow it to be mounted to the actual MH. It has its own ground rod. In this panel there is a breaker for the MH, one for the 5 ton A/C-heat pump and another for the heat strips in the A/C unit. There is also a breaker for a 120v receptacle at the pole.

3) There is the panel that came in the house. It has a 200 AMP main and the breakers for the rest of the house. We were required to also install a ground rod for this panel and have that connected to the frame of the house.

Panels number 2 and 3 have un-bonded neutrals as per local code.

 

[TMB1320]

Going to show us the "plug" for bonding Stoney? IMHO the only safe way to do this is with welding cable,
one piece, bolted connections at each end. Safety trumps convenience every time. I'd settle with a welding cable extension, the connectors are solid. Put on some kind of lock with a key that's on your
keyring. There should never be a way of that being disconnected without you knowing. Give **** a place to happen and sooner or later, it will.

 

[stonypass]

Currently mine looks just like the one below, except I used a 20amp 120v capable plug with a 10ga jumper.
May make up one using a 50amp plug with a 6ga jumper though, since to connect the genset to the house it would have to be removed as my cord uses that receptacle.

 

[hr3]

No, the grounding electrode (ground rod) has nothing to do with clearning a ground fault.



This is correct, but it's assuming that your generator was either manufacutred without the neutral and equipment ground bonded or that there is a removable bonding jumper. Your generator was not manufactured this way and should not be modified. The generator was designed, manufactured, and tested by a third party to ensure that it meets certain safety standards. Modifying the generator changes the system, voids the tests, is prohibited by code (see NEC 90.7, 110.2, and 110.3), and would not be recommended by anyone who understands the hazards involved.




The purpose of the neutral to equipment ground bond is to conduct fault current. If you have a fault between the ungrounded (hot) and equipment ground, then all of the faul current must flow through the plug/jumper in the photo. I would not trust that and would not be surprised if the circuit breaker never opened during a fault, as the resistance of this configuration is much higher than a solid connection. That is a fire hazard. Also, if there is a bad connection in the plug/jumper and there was a fault, the chasis of the generator would be energized and you could be shocked or electrocuted. The same is true if you separate the neutral and equipment ground and connect the generator to your premises wiring system the way you describe. A bad connection at the plug will result in shock/electrocution hazard and/or fire hazard if you have a fault between the hot and equipment ground.

I agree with most everyting you are saying,, All except for the part about the 50a plug and receptical not being able to clear the fault.. If the plug is UL inspected and sized for the load then there is no problem useing it..

 

[hr3]

Re: PTO Generator Now Wired and Tested

After much consideration, I modified the generator to have a Floating Neutral and made up a plug that Bonds Neutral to Ground for standalone usage.

A clamp-on meter from HF was used to test current draw on all my high usage items so I would know what combinations I am able to use with the genset at the same time.
I also mounted a remote 120v outlet on the front of my TSC carry-all for a Kill-A-Watt that can be seen from the tractor seat (or from the ground) for properly setting frequency.
An outlet tester shows proper configuration at 120v outlets in the home when the genset is connected and running, and the generator shows the same in standalone mode when using the bonding plug.

Yesterday I did a full test of the Generator and ran everything in the house, setting the frequency at 62hz with no load and then testing first lights, high usage items then electronics.
My high usage items are a 1.5hp 650ft well pump, electric dryer, range/stove, and a 4 ton central A/C unit.
The generator had no problems with any of these and will easily run the well pump with any other single high usage item along with lights, refrigerator/freezer, TV/Satellite and PC/Internet.
The Kubota has plenty of power with 37 PTO hp and I never saw lights flicker, the rpm vary much or the frequency go below 60hz under the highest loads.

This setup may not suit everyone but will provide emergency power to anywhere in my home and barn which is what I was after.
Thanks to all who responded, your advice was appreciated.

I would like to add a pilot light to the breaker box to tell me when grid power has been restored, if someone can point me to a link for a suitable Neon or LED light and holder that can be hooked to one side of my input power I would appreciate it.

Nice setup and well tested by the sounds of it..