neutral bonding at the generator

[coyote62ny]

i searched the other posts on this and cant find where anyone positivly answers the question will the mep-003 operate and do it safly with the neutral bond seperated from ground . i have a mep-003 and my house is set up as a non seperately derived system yes i have the transfer bar so you cant have the generator breaker on when the mains are on it blocks one breaker or the other an answer would be a great help thanks in advance

 

[stampy]

IMO better to put in an earth ground for the generator also. But my house is wired with the generator two hot 110 legs and the neutral to the neutral buss and the ground to the neutral buss. The earth ground for the house acts as the ground for the genset(for now) but I plan on putting in the grounding rod (better safe than sorry). So yes I think you can safely setup (as you asked) as that is how mine is setup by an ex power company (25 years) electrician.

 

[shovelheadmike]

I grounded my generator with its own ground rod. Also bonded it.to the metal gas line in the ground. I did not pull a.ground from the generator to the transfer switch or house panel. Passed inspection just fine.

 

[shovelheadmike]

Perhaps I did not answer the specific question. No, I did not bond the gen neutral to the gen ground. When powering your house like that, bonded at both the gen and panel would create a path for circulating current and is frowned upon.

Neutral should only be bonded to ground at one place--service disconnect. Gen will run fine.

 

[Rustygears]

The pole transformer for standard supply has the neutral bonded. The gen set should be as well afaik check NEC. There is no ground loop through physical earth. Wired earth ( protective earth) yes, but the soil, no.

 

[mistaken1]

i searched the other posts on this and cant find where anyone positivly answers the question will the mep-003 operate and do it safly with the neutral bond seperated from ground . i have a mep-003 and my house is set up as a non seperately derived system yes i have the transfer bar so you cant have the generator breaker on when the mains are on it blocks one breaker or the other an answer would be a great help thanks in advance

According to this the generator neutral (grounded conductor) is not to be bonded the grounding electrode system. However the generator ground (grounding conductor) is to be bonded to the grounding electrode system.

In other words keep the generator neutral isolated from the generator ground but make sure the generator neutral is connected to the house neutral and the generator ground is connected to the house ground. There is only one point where the neutral and ground are connected together and that is at the house service panel (or meter).

All of this is based on your description of a Non-Separately Derived System.


Generator Grounding

 

[steelandcanvas]

 

[coyote62ny]

yes i do have a ground rod at the generator neutral is hooked up with a 200 amp battery disconnect switch so i can have it bonded or unbonded my concern was will the mep-003 run and operate correctly with the neutral unbonded at the gen it will be bonded at the service panel

 

[212sparky]

You only want one point of bonding. It is to be done at your point to disconnect (your main breaker). make sure the frame of your gen set is grounded for safety.

 

[mistaken1]

yes i do have a ground rod at the generator neutral is hooked up with a 200 amp battery disconnect switch so i can have it bonded or unbonded my concern was will the mep-003 run and operate correctly with the neutral unbonded at the gen it will be bonded at the service panel

Do you have a wire that connects your neutral (grounded conductor) to the generator frame?

Is your ground rod bonded to the generator frame?

 

[AN/ARC186]

yes i do have a ground rod at the generator neutral is hooked up with a 200 amp battery disconnect switch so i can have it bonded or unbonded my concern was will the mep-003 run and operate correctly with the neutral unbonded at the gen it will be bonded at the service panel

The mep-003 will operate correctly with the neutral to ground bond removed at the generator.
since you are running hot, neutral(ungrounded) and grounded conductors from the generator to the transfer point your house panel bonding becomes the generator bond.

 

[Stalwart]

So correct me if I'm wrong here Dan, the only worry here is if you have a failure of the generator neutral to house neutral connection. Since I would assume most would be using a 4 conductor cable between the generator and home panel, wouldn't the neutral and ground connections offer a bit of safety and redundancy? But for that redundency, wouldn't the generator need to be bonded between ground and neutral? There is a reason I like DC . . .

 

[AN/ARC186]

it all comes back to the seperately derived system fandango.
I'm with you on the DC...

 

[coyote62ny]

ground rod is hooked to the generator with copper ground cable. neutral wire is bonded with the switch in one position and unbonded in the other position so i can use it to run the house or the shop and my welder

 

[cvh20]

The key to the whole seperately derived system nomenclature is "are you switching the neutral when you transfer to the generator". If you do switch to an isolated generator neutral like coyote62ny just described, you have a seperately derived system. If you connect your generator neutral to your house neutral solidly (not switched), then you have a non-seperately derived system (90% of systems are connected this way). Remember, if you do switch the neutral during transfer, the generator should be treated like its own seperate electrical service. This means it needs its own grounding electrode conductor - least a ground rod, plus one other grounding electrode (cold water pipe, metal gas line, auxillary ground rod, etc) AND your neutral and ground are tied together in the generator (because this is now the first means of disconnect). Confused yet?

 

[Stalwart]

Cvh, that was clear to me and makes sense . . . therefore I musta missed something.

 

[cvh20]

I design, sell, and install standby generator systems for a living.....been through this many a time with Mr. Building Inspector

 

[PeterD]

... Confused yet?

Excellent description of the situation!

 

[steelandcanvas]

The key to the whole seperately derived system nomenclature is "are you switching the neutral when you transfer to the generator"...Confused yet?

Best explaination yet.

 

[mistaken1]

ground rod is hooked to the generator with copper ground cable. neutral wire is bonded with the switch in one position and unbonded in the other position so i can use it to run the house or the shop and my welder

So the generator frame is always connected to the ground rod and the 'bonding switch' lets you bond and unbond the grounded conductor at the generator as needed.

When the generator is powering the house the 'bonding switch' is open and grounded conductor/grounding conductor bonding takes place at a single point in the house panel.

When the generator is powering the welder the house wiring is not connected to the generator and the 'bonding switch' is closed so that the grounded conductor/grounding conductor bonding takes place at a single point at the generator.

Nice design, thanks for sharing!



The whole point is the grounded conductor (neutral) is required to be bonded to ground (grounding electrode system/grounding conductor) at one point and only one point.

A rule of thumb would be if the grounded conductor (neutral) of your generator is solidly connected to your house grounded conductor (neutral) then do not bond the grounded conductor (neutral) to the the grounding conductor (green or bare or generator frame) at the generator. {there is an exception involving a transfer switch that switches the grounded conductor (neutral) but now you have to know where your house bond takes place and whether or not the generator 'sees' that bond when it is connected, some bonds take place in the main panel, some in the meter can, are you powering your main panel or just a sub-panel of critical loads; call a qualified electrician if you are not sure}

On the other hand if you are using your generator in a stand alone capacity (powering a tent city or a welder in your barn for example) then bond the grounded conductor (neutral) the the grounding conductor (green or bare or generator frame) at the generator.