cbskies
Member
- Location
- Crested Butte, CO, USA
Grettings everyone!
First I want to say that I have been coming to this forum for quite some time and have always found it to be a great source of information and clarification, a big thanks to everyone here! This is my first post so please bear with me.
I have a friend who had purchased a back-country cabin and his original electrician abandoned the solar project so I have stepped in to help get it finished. I am a licensed residential wireman but have little experience with solar. We have gotten the system up and running but I have found myself confused over the proper grounding for this system, any help would be greatly appreciated.
First a description of the system. Approximately 100-150' from the cabin he has a pole-mounted DC pv array with 6 panels wired three panels in series for two parallel DC circuits with a maximum output of approximately 1500W. This pole is a large metal pole (8" diameter maybe) concrete-encased approximately 8' in the earth, continuous metal mounting from pv array rack to the continuously welded structure of pole. About 15' from the pole there is a small shed which contains the PV array combiner box which has two 125V / 20A DC disconnects and sends one DC circuit to the cabin.
Also in the shed is a propane powered 8kw generator. About 25' from the shed is an approximately 300' water well with a 230v 9A AC well pump with pump controls in the shed. From the shed there is a single 2" PVC conduit run to the cabin crawl space.
Inside the cabin mech room he has an Outback charge controller (FLEXmax80), a 48v 500Ah battery bank, and an Outback FX series inverter setup (pretty sure it is the FLEXpower TWO system) which feeds an AC subpanel. Both AC and DC sides of the inverter have separate 6awg copper runs going to a single ground rod, and there is a system bonding jumper on the AC side bonding the AC neutral to ground.
So for clarification, in the 2" PVC there are four wires, 6-2 romex going from combiner box to charge controller, 10-3 romex going from backup generator to ac inputs on inverter, 10-2 romex going from pressure switch in cabin to well pump controls, and a 14-2-2 romex which is being used (2 conductors) as signal wire for turning on/off generator from the aux outputs of the master inverter through a 12v relay.
From my description you may already be aware of code violations here, namely high and low voltage wiring sharing the same raceway (pvc from shed to house). As stated I am picking up an abandoned project and just want to get the system running for now and safely/ properly grounded and bonded as per NEC. The area is about 7-8' buried in snow so separate underground conduits will have to be addressed later.
So here are my questions:
Currently there is an equipment grounding conductor in the 6-2 romex run from the DC side ground bus on the inverter which goes out to the pv combiner box in the shed. Do I need to run an equipment grounding conductor from the array/ pole to the combiner box ground bus? From my (limited) understanding the pole on which the array is mounted should serve as an adequate grounding electrode for the array correct? If I run an equipment grounding conductor to the array won't this create a large ground loop between the cabin grounding electrode and the pv array pole? Having watched Mike Holt's youtube video on Grounding Myths I am under the impression that this is undesirable especially in the case of a nearby lighting strike which is likely as this cabin is high in the mountains.
Along the same note, should I have an equipment grounding conductor running from the cabin to the well casing? Wouldn't this well casing serve as a far better grounding electrode than the ground rod outside the cabin and again wouldn't this create another large ground loop in the system? It would in fact be three grounding electrodes tied together, the cabin ground rod, the pv pole, and the well casing. Is this ok? Currently I understand this to be undesirable, in the case of a large voltage gradient due to nearby lightning strike as there could potentially be very high voltage currents running through the grounding system potentially damaging equipment, or is this incorrect?
Third, currently the neutral and ground of the backup generator seem to be bonded as I get 120v AC from both hot legs of the generator to the generator chassis. Currently the generator does not have it's own grounding electrode. I am under the impression that the ground to neutral bond should remain in the AC side of the inverter as the inverter is the main source of power for the cabin, and the generator is typically only for charging the batter bank should it get low, so do I need to remove the ground to neutral bond in the generator and then ground the generator chassis using the equipment grounding conductor in the 10-3 romex running from the cabin? Also this generator has it's own separate stand alone 12v battery and small pv array for startup. the negative of this battery is also run to the generator chassis as would be typical I believe. Currently I have disconnected the equipment grounding conductor between the inverter ac ground bus and the generator thinking it would be best to give the generator it's own grounding electrode.
So i've been scratching my head over these questions and not having been able to come up with answers in other posts or in videos, or the code book itself, I've finally created an account and posted here, thanks a million to anyone who can give me some grounding guidance!
First I want to say that I have been coming to this forum for quite some time and have always found it to be a great source of information and clarification, a big thanks to everyone here! This is my first post so please bear with me.
I have a friend who had purchased a back-country cabin and his original electrician abandoned the solar project so I have stepped in to help get it finished. I am a licensed residential wireman but have little experience with solar. We have gotten the system up and running but I have found myself confused over the proper grounding for this system, any help would be greatly appreciated.
First a description of the system. Approximately 100-150' from the cabin he has a pole-mounted DC pv array with 6 panels wired three panels in series for two parallel DC circuits with a maximum output of approximately 1500W. This pole is a large metal pole (8" diameter maybe) concrete-encased approximately 8' in the earth, continuous metal mounting from pv array rack to the continuously welded structure of pole. About 15' from the pole there is a small shed which contains the PV array combiner box which has two 125V / 20A DC disconnects and sends one DC circuit to the cabin.
Also in the shed is a propane powered 8kw generator. About 25' from the shed is an approximately 300' water well with a 230v 9A AC well pump with pump controls in the shed. From the shed there is a single 2" PVC conduit run to the cabin crawl space.
Inside the cabin mech room he has an Outback charge controller (FLEXmax80), a 48v 500Ah battery bank, and an Outback FX series inverter setup (pretty sure it is the FLEXpower TWO system) which feeds an AC subpanel. Both AC and DC sides of the inverter have separate 6awg copper runs going to a single ground rod, and there is a system bonding jumper on the AC side bonding the AC neutral to ground.
So for clarification, in the 2" PVC there are four wires, 6-2 romex going from combiner box to charge controller, 10-3 romex going from backup generator to ac inputs on inverter, 10-2 romex going from pressure switch in cabin to well pump controls, and a 14-2-2 romex which is being used (2 conductors) as signal wire for turning on/off generator from the aux outputs of the master inverter through a 12v relay.
From my description you may already be aware of code violations here, namely high and low voltage wiring sharing the same raceway (pvc from shed to house). As stated I am picking up an abandoned project and just want to get the system running for now and safely/ properly grounded and bonded as per NEC. The area is about 7-8' buried in snow so separate underground conduits will have to be addressed later.
So here are my questions:
Currently there is an equipment grounding conductor in the 6-2 romex run from the DC side ground bus on the inverter which goes out to the pv combiner box in the shed. Do I need to run an equipment grounding conductor from the array/ pole to the combiner box ground bus? From my (limited) understanding the pole on which the array is mounted should serve as an adequate grounding electrode for the array correct? If I run an equipment grounding conductor to the array won't this create a large ground loop between the cabin grounding electrode and the pv array pole? Having watched Mike Holt's youtube video on Grounding Myths I am under the impression that this is undesirable especially in the case of a nearby lighting strike which is likely as this cabin is high in the mountains.
Along the same note, should I have an equipment grounding conductor running from the cabin to the well casing? Wouldn't this well casing serve as a far better grounding electrode than the ground rod outside the cabin and again wouldn't this create another large ground loop in the system? It would in fact be three grounding electrodes tied together, the cabin ground rod, the pv pole, and the well casing. Is this ok? Currently I understand this to be undesirable, in the case of a large voltage gradient due to nearby lightning strike as there could potentially be very high voltage currents running through the grounding system potentially damaging equipment, or is this incorrect?
Third, currently the neutral and ground of the backup generator seem to be bonded as I get 120v AC from both hot legs of the generator to the generator chassis. Currently the generator does not have it's own grounding electrode. I am under the impression that the ground to neutral bond should remain in the AC side of the inverter as the inverter is the main source of power for the cabin, and the generator is typically only for charging the batter bank should it get low, so do I need to remove the ground to neutral bond in the generator and then ground the generator chassis using the equipment grounding conductor in the 10-3 romex running from the cabin? Also this generator has it's own separate stand alone 12v battery and small pv array for startup. the negative of this battery is also run to the generator chassis as would be typical I believe. Currently I have disconnected the equipment grounding conductor between the inverter ac ground bus and the generator thinking it would be best to give the generator it's own grounding electrode.
So i've been scratching my head over these questions and not having been able to come up with answers in other posts or in videos, or the code book itself, I've finally created an account and posted here, thanks a million to anyone who can give me some grounding guidance!