Fried circuit board on generator

Status
Not open for further replies.
A

andyandy

Member
I have a client who has a non seperatly derived generator installaed on a property to act as back up power for a couple of homes. Someone installed a sub-panel (part of thesame system) directly to the generator to feed a well pump. There was a short circuit in the well pump that ended up frying the circuit board and some other electronics in the generator. When i investigated the problem I found that the subpanel which is about 400' from the electrical service did not have ground coming in with the feeders but had a uffer ground. when testing the uffer ground there was much more resistance than the ground coming from the generator. That is what probably caused the electronics to burn up. My question is though is the installer of the panel at fault for the electronics burning up? or should this panel have been part of the same grounding system as the generator because they are all part of the same electrical system? If someone could respond with NEC references I would be very appreciative
 
andyandy said:
I have a client who has a non seperatly derived generator installaed on a property to act as back up power for a couple of homes. Someone installed a sub-panel (part of thesame system) directly to the generator to feed a well pump. There was a short circuit in the well pump that ended up frying the circuit board and some other electronics in the generator. When i investigated the problem I found that the subpanel which is about 400' from the electrical service did not have ground coming in with the feeders but had a uffer ground. when testing the uffer ground there was much more resistance than the ground coming from the generator. That is what probably caused the electronics to burn up. My question is though is the installer of the panel at fault for the electronics burning up? or should this panel have been part of the same grounding system as the generator because they are all part of the same electrical system? If someone could respond with NEC references I would be very appreciative
Click to expand...
Highlights by CF
Take a look at Outside Feeders, Art 225. That's the regulation - which may have little to do with the design needs.

I'm confused why a short circuit in a well pump would cause gen electronics to burn out. Short circuits usually trip circuit breakers. I wouldn't expect that to affect generator control electronics.

cf
 
I failed to include this oart in the original post
A maintenance worker repeatedly tried to reset the tripped 20 amp breaker. Hetold me everytime he tried to reset the breaker the engine of the generator would turn over.
 
I found that the subpanel which is about 400' from the electrical service did not have ground coming in with the feeders but had a uffer ground. when testing the uffer ground there was much more resistance than the ground coming from the generator. That is what probably caused the electronics to burn up.
Click to expand...
Highlights by CF
If it was installed a couple of cycles ago it may well have met code at that time. You will need to check the code that was in force at the time of the install.

Curiosity Question: How did you test the two ground resistances? Fall of potential? Clamp-on ground resistance tester?

Q2; I'm still confused. How would a difference in ground resistance between the generator ground and the subpanel ground cause the gen electronics to burn up? What is it you think happened that caused the electronics to burn?

A maintenance worker repeatedly tried to reset the tripped 20 amp breaker. Hetold me everytime he tried to reset the breaker the engine of the generator would turn over.
Click to expand...
Sounds like the shorted pump is drawing enough current to pull the voltage down at the gen enough to make the gen electronics think the normal power is failing and it trys to to start the gen. Makes one wonder if the gen electronics are not up to 20 starts is two minutes.

cf
 
A maintenance worker repeatedly tried to reset the tripped 20 amp breaker. Hetold me everytime he tried to reset the breaker the engine of the generator would turn over
Click to expand...

Did he think the problem would heal it's self:-?

Sounds like the shorted pump is drawing enough current to pull the voltage down at the gen enough to make the gen electronics think the normal power is failing and it trys to to start the gen. Makes one wonder if the gen electronics are not up to 20 starts is two minutes.

cf
Click to expand...

One thing the OP did not say is how this gen. is switched. You can only assume by a ATS. By the maint. worker doing what you say he did I would agree that that would more than likely be the cause of the problem. The combination of the distance of the sub panel, (OP did not state what wire size), and the short was probably enough to make the gen. think that the utility was failing. And by him repeatedly resetting the breaker caused a failure in the electronics
 
andyandy said:
I have a client who has a non seperatly derived generator installaed on a property to act as back up power for a couple of homes. Someone installed a sub-panel (part of thesame system) directly to the generator to feed a well pump. There was a short circuit in the well pump that ended up frying the circuit board and some other electronics in the generator. When i investigated the problem I found that the subpanel which is about 400' from the electrical service did not have ground coming in with the feeders but had a uffer ground. when testing the uffer ground there was much more resistance than the ground coming from the generator. That is what probably caused the electronics to burn up. My question is though is the installer of the panel at fault for the electronics burning up? or should this panel have been part of the same grounding system as the generator because they are all part of the same electrical system? If someone could respond with NEC references I would be very appreciative
Click to expand...

So what feeds this well pump when the generator is not running? How exactly is this back up system wired?:confused:
 
andyandy said:
My question though is the installer of the panel at fault for the electronics burning up?
Click to expand...
I am going to put a temporary hold on this thread. I need to know the reason for your inquiry. If you are looking to troubleshoot, to repair, and to prevent recurrence, we can help you. If you are looking for a reason to place the blame on someone, or to prevent the blame from being placed on someone, if essentially this is a legal dispute over who has to pay for repairs, then forum rules prohibit us from participating.

Please send me a private message to explain the circumstances.
 
Status
Not open for further replies.
Top