Note: after 250.34

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romeo

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I am confused. Note: after 250.34 reads:A portable or vehicle-mounted generator suppling fixed wiring for a
premises must be grounded (connected to earth) and bonded in accordance with 250.30 for separately systems
and 250.35 for nonseparately derived systems.

Maybe I am misunderstanding how this is written. My understanding is 250.30 would require the neutral to be
boned at the generator, and 250.35 would not want the neutral to be bonded at it.

Also what happens if a portable generator is used to supply a premises during a power outage using cord and receptacles (Gentran) to connect to the service, and removes the plug connection when power is restored, and uses the generator as portable, now IMO the neutral would have to be bonded.

Explanation please am I missing something?

Thanks
 
Note after 250.34

Note after 250.34

K8MHZ said:
See definition of 'grounded'

"Connected to earth or to some conducting body that serves in place of the earth."

To me, that means that the metal frame or chassis of a vehicle could serve as a conducting body in place of the earth.
Click to expand...

Thank you for the response.I understand what they are saying about grounded, they want a GES. I am just confused about one NEC section requiring the neutral bonded and the other not.
 
One section is for separately derived systems and the other is not. If the transfer switch switches the neutral you have a separately derived system. The non separately derived system is bonded through the main bonding jumper at the service equipment. The separately derived system switches the neutral and is no longer bonded through the service when that part of the transfer switch opens.
 
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romeo said:
I am confused. Note: after 250.34 reads:A portable or vehicle-mounted generator suppling fixed wiring for a
premises must be grounded (connected to earth) and bonded in accordance with 250.30 for separately systems
and 250.35 for nonseparately derived systems.

Maybe I am misunderstanding how this is written. My understanding is 250.30 would require the neutral to be
boned at the generator, and 250.35 would not want the neutral to be bonded at it.

Also what happens if a portable generator is used to supply a premises during a power outage using cord and receptacles (Gentran) to connect to the service, and removes the plug connection when power is restored, and uses the generator as portable, now IMO the neutral would have to be bonded.

Explanation please am I missing something?

Thanks
Click to expand...

Wouldn't the neutral be bonded merely by using cord and plug connections?
 
Hv&Lv said:
Wouldn't the neutral be bonded merely by using cord and plug connections?
Click to expand...

Not in a separately derived system where the transfer switch opens the neutral from the service when transfering. Then you will need a bond someplace on the separately derived system.
 
Note: after 230.34

Note: after 230.34

kwired said:
One section is for separately derived systems and the other is not. If the transfer switch switches the neutral you have a separately derived system. The non separately derived system is bonded through the main bonding jumper at the service equipment. The separately derived system switches the neutral and is no longer bonded through the service when that part of the transfer switch opens.
Click to expand...

Thank You, but I understand all of that. If I understand the note in the NEC book after 250.34 I am being told that both systems are treated the same,and need a GES, at the generator and one is separately derived and the other isn't so
IMO they can not be treated the same.

Maybe I am not understanding the note, or reading it wrong.
 
If the generator is supplying power (non-separately derived ) to a fixed wiring system then it must use the GES for that system.

It must have a separate GES if it is separately derived.

Either way you must have a GES, but they are not the same GES.
 
SG-1 said:
If the generator is supplying power (non-separately derived ) to a fixed wiring system then it must use the GES for that system.

It must have a separate GES if it is separately derived.

Either way you must have a GES, but they are not the same GES.
Click to expand...

Exactly. When non separately derived you already have the GES from the service and you are tied into it. With the SDS you are isolated from the service GES and you need an additional GES for the SDS.

The thing that makes this all seem stupid is both need bonded together - effectively making them one GES anyway.

Switching the neutral with the transfer switch keeps neutral current in desired paths though, otherwise it will flow on other equipment grounding paths because they are parallel to the neutral if it is bonded in more than one place.
 
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