System Grounding

[nasty]

Hello
Does this look right for grounding? Do I need a bond between the neutral and ground? If so can I make it from ground bus to the negative tie point? There is also going to be a Morningstar 300 inverter that will be wired into the AC load panel with a transfer switch between it and the other 1000w inverter that has a GFCI. Any advice would be appreciated.

Cabin Solar.JPG

[Sunking]

Where is your DC protection?

[garybeck]

Hello
Does this look right for grounding? Do I need a bond between the neutral and ground? If so can I make it from ground bus to the negative tie point? There is also going to be a Morningstar 300 inverter that will be wired into the AC load panel with a transfer switch between it and the other 1000w inverter that has a GFCI. Any advice would be appreciated.

[ATTACH=CONFIG]2018[/ATTACH]

I'm not an electrician, but your battery negative should be grounded. this can be done at the bus bar but I think it's preferred to have a separate wire going from the battery neg directly to the ground rod. Also some would say you should have a separate ground wire from the frame of the PV directly to the ground rod, or even use a 2nd separate ground rod. It depends how far you want to go.... but in general, the system negative should be tied to ground.

by the way, nice drawing!

[Sunking]

I'm not an electrician, but your battery negative should be grounded. this can be done at the bus bar but I think it's preferred to have a separate wire going from the battery neg directly to the ground rod. Also some would say you should have a separate ground wire from the frame of the PV directly to the ground rod, or even use a 2nd separate ground rod.

No offense but you would not make a good electrician, but a very deadly one at that as your advice is dead wrong and violates all known electrical codes. You have one point right the battery needs to be grounded with the way the over current protection is shown, the rest is completely wrong.

[garybeck]

No offense but you would not make a good electrician, but a very deadly one at that as your advice is dead wrong and violates all known electrical codes. You have one point right the battery needs to be grounded with the way the over current protection is shown, the rest is completely wrong.

Uh, maybe if you could say specifically what I said wrong, that would actually be helpful instead of condescending.

You said "the rest is completely wrong." What exactly is wrong? Grounding the battery is really the only thing I said, and you said that is right. Geeze...

[Sunking]

Uh, maybe if you could say specifically what I said wrong

Sorry for the tone but your advice is dangerous and directly does not comply with several electrical codes like:

250.4 General Requirements for Grounding and Bonding.
(4) Path for Fault Current.

Electrical equipment, wiring, and other electrically conductive material likely to become energized shall be installed in a manner that creates a low impedance circuit from any point on the wiring system to the electrical supply source to facilitate the operation of overcurrent devices should a second ground fault from a different phase occur on the wiring system. The earth shall not be considered as an effective fault-current path.

250.58 Common Grounding Electrode.

Where a electrical system is connected to a grounding electrode in or at a building or structure, the same electrode shall be used to ground conductor enclosures and equipment in or on that building or structure. Where separate services, feeders, or branch circuits supply a building and are required to be connected to a grounding electrode(s), the same grounding electrode(s) shall be used. Two or more grounding electrodes that are bonded together shall be considered as a single grounding electrode system in this sense.

250.60 Use of Air Terminals.

Air terminal conductors and driven pipes, rods, or plate electrodes used for grounding air terminals shall not be used in lieu of the grounding electrodes required by 250.50 for grounding wiring systems and equipment. This provision shall not prohibit the required bonding together of grounding electrodes of different systems.

So what all this code junk is saying is you cannot have separate grounding systems as you describe. To do so would be incredible dangerous. So when I said ground a terminal of the battery is correct. Which polarity is insignificant and may not be required at all if certain conditions are met. But the rest suggesting separate isolated ground systems is incorrect.

[garybeck]

OK so you're saying not to install a 2nd ground rod, and to use a common ground rod. All I really said was that his battery negative needs to be grounded which appears to be correct. other than that I don't see how your cut/paste work really applies. I don't see what I said that is so dangerous. I just said he needs to ground his battery. To be helpful to the person who asked the question (and any others who may be reading), i would think it would be much more useful if you could make specific recommendations for improving his design, rather than just say the whole thing is dangerous and attack others who are trying to help. Have a nice day.

[russ]

OK so you're saying not to install a 2nd ground rod, and to use a common ground rod. All I really said was that his battery negative needs to be grounded which appears to be correct. other than that I don't see how your cut/paste work really applies. I don't see what I said that is so dangerous. I just said he needs to ground his battery. To be helpful to the person who asked the question (and any others who may be reading), i would think it would be much more useful if you could make specific recommendations for improving his design, rather than just say the whole thing is dangerous and attack others who are trying to help. Have a nice day.

If you are going to give directions you need to be specific - you left it wide open as to how many grounds there would be.

[Sunking]

OK so you're saying not to install a 2nd ground rod.

No I did not say any such thing. Code minimum is 2 rods and you can use 100 of them. Trick is as I cut and Pasted all the rods MUST be bonded together to form a common Ground Electrode System.

All I really said was that his battery negative needs to be grounded which appears to be correct. other than that I don't see how your cut/paste work really applies. I don't see what I said that is so dangerous.

OK I will point it out.

I think it's preferred to have a separate wire going from the battery neg directly to the ground rod. Also some would say you should have a separate ground wire from the frame of the PV directly to the ground rod, or even use a 2nd separate ground rod.

You are implying separate systems that are not bonded together.

What the code refferences is telling you it should be like this.

[rob.tyler.phillips]

Test post. Thanks for the diagrams, guys

[cyby]

I would like to ask the reason for grounding the pv panels and the negative terminal of the batteries if someone can tell m.

[inetdog]

I would like to ask the reason for grounding the pv panels and the negative terminal of the batteries if someone can tell m.

The framework and other metal parts of the panels (not electrically connected to the cells themselves) needs to be grounded for lightning protection and for safety if a short develops between a high voltage (either DC or AC) and the frame.

The grounding of one of the sides of the DC circuit (at panel or at battery) is more controversial. In the US it is required by the electrical code. The alternative is to run the DC ungrounded but to provide a detector to alarm and shut down if a connection to ground suddenly appears (like the above mentioned short circuit.) Most forum members with professional knowledge seem to favor the latter. But it is not code, so....

[Sunking]

The grounding of one of the sides of the DC circuit (at panel or at battery) is more controversial. In the US it is required by the electrical code. The alternative is to run the DC ungrounded but to provide a detector to alarm and shut down if a connection to ground suddenly appears (like the above mentioned short circuit.) Most forum members with professional knowledge seem to favor the latter. But it is not code, so....

OK here is a different spin and a more specific answer. In order for a fuse or breaker to operate requires a planned fault path to induce enough current to operate the fuse or breaker. Without a low resistance planned path, a fault would not induce enough current to open the fuse.

Here is a good example. One is to code and will work great, the other one will get you killed. Can you tell which one? They are both grounded to earth or dirt. One will work, and the other will not.

[cyby]

I have read the previous parts of this thread. I was only a bit confused about the reasons of grounding the negative terminal.

[Sunking]

I have read the previous parts of this thread. I was only a bit confused about the reasons of grounding the negative terminal.

Like I said you have to have a planned path to operate a fuse or breaker. The easiest and least expensive way is to operate a Grounded System. Do not confuse ground and grounded system as they are completely different things.