Regarding portable generators why isnt a seperately derived generator required to have a ground rod? Secondly I read a thread on this before and it was mentioned that if a portable generator was to have a ground rod then it would increase the danger, why? If a large hard wired generator needs to have an electrode why not a portable? is it because of the lower voltage?Thirdly i understand that a sperately derived system creates its own neutral and the neutral is bonded to the case and the case is bonded to an electrode, is this all factory made with portable generators? and if this sd system is required to have an electrode why not the portable types?? thanks
generators
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websparky
Senior Member
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Re: generators
Most all of the answers are here:
250.34 Portable and Vehicle-Mounted Generators.
Most all of the answers are here:
250.34 Portable and Vehicle-Mounted Generators.
Because if lightning hits the generator, a rod ain't gonna help!
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- Massachusetts
Re: generators
If the generator stays isolated the person touching a 'hot' conductor form the generator will not get a shock.
And what Websparky said.
[ November 22, 2004, 07:40 PM: Message edited by: iwire ]
It would not provide any additional safety for the operators of the generator or the portable equipment connected to it.
The increased danger would be the fact that now a person that was standing on wet ground who contacts a 'hot' wire will receive a shock.
If the generator stays isolated the person touching a 'hot' conductor form the generator will not get a shock.
I believe it is the building or structure that benefits from a grounding electrode, not specifically the generator.
And what Websparky said.
[ November 22, 2004, 07:40 PM: Message edited by: iwire ]
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Re: generators
I believe that the code is simply recognizing the fact that a portable generator cannot be connected to a permanent ground rod. What would you have the owner do? Install a ground rod at every location to which the portable generator is moved, and then either dig it out again or abandon it in place?
The reason this is safe is that there are two requirements you must meet, in order to use the frame as the grounding electrode (i.e., not connected to planet Earth). 250.34(A) says that all loads must be either on the generator or supplied by cord & plug via receptacles on the generator. It also says that the ground pin of the receptacles on the generator must be bonded to the frame.
What do these two requirements accomplish? Suppose there is a fault from one hot conductor of a tool (i.e., one that is plugged into this generator) to the case of that tool. The fault current would flow from the case, along the cord?s EGC to the receptacle on the generator, to the frame, and finally back to the neutral of the generator (since it is bonded to the frame). This completes a fault path of low resistance, and the resulting high current will trip the generator breaker. If you are leaning against the frame, standing with muddy shoes on wet dirt, when the event happens, you will not be shocked. That is because the fault current is seeking a path back to its source, and planet Earth is not part of the path.
I believe that the code is simply recognizing the fact that a portable generator cannot be connected to a permanent ground rod. What would you have the owner do? Install a ground rod at every location to which the portable generator is moved, and then either dig it out again or abandon it in place?
The reason this is safe is that there are two requirements you must meet, in order to use the frame as the grounding electrode (i.e., not connected to planet Earth). 250.34(A) says that all loads must be either on the generator or supplied by cord & plug via receptacles on the generator. It also says that the ground pin of the receptacles on the generator must be bonded to the frame.
What do these two requirements accomplish? Suppose there is a fault from one hot conductor of a tool (i.e., one that is plugged into this generator) to the case of that tool. The fault current would flow from the case, along the cord?s EGC to the receptacle on the generator, to the frame, and finally back to the neutral of the generator (since it is bonded to the frame). This completes a fault path of low resistance, and the resulting high current will trip the generator breaker. If you are leaning against the frame, standing with muddy shoes on wet dirt, when the event happens, you will not be shocked. That is because the fault current is seeking a path back to its source, and planet Earth is not part of the path.
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