Zwy
Solar Wizard
All the more reason to have a 4 wire feeder.
Extra/Auxilary grounding rods..... Don't do it.
- Thread starter FilterGuy
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Zwy
Solar Wizard
That small amount of electrical static will easily be pulled to zero voltage potential thru the EGC back to system grounding electrode.
We arent concerned with the structure, it only needs the tied egc, the EARTH around and under the structure needs the ground rod to keep earth at same potential as building.
timselectric
If I can do it, you can do it.
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I can see a static discharge, maybe.
But I can't imagine it rising the level of dangerous.
I still think that it would require miles of distance.
Yeah, i dont see it as a problem either, but thats the rationale around needing it...
FilterGuy
Solar Engineering Consultant - EG4 and Consumers
yup. Sometimes it is impossible to avoid creating a ground at the array.
Warning: Some folks that I respect disagree with the following recommendation:
The code allows the solar EGC to be routed directly to the main breaker panel.... so I recommend doing that rather than routing it to the ground in the inverter.
The upside: An surface-wave pulse/spike current going through the EGC will no go through the inverter.
The Downside: The ground-fauilt path will be much longer. (All the way to the main breaker and back to the inverter).
There is no perfect solution. no mater how it is down there is a compromise.
Quattrohead
Solar Wizard
Us human's can fight and argue and implement our own choices as much as we like, at the end of the day mother nature will always win.
Lightning is her fun toy.
Lightning is her fun toy.
ksmithaz1
Solar / EV Junkie
Umm, I dunno.
In Virginia Beach the water table is very low. Now this was a very long time ago, but I had a problem once with a SPA about 40-50' away from the house every time the ground was saturated with water, after rain, The unit was connected to 240v only grounded at the pad the spa was on to a box with 3 wires, N+L1+L2. It kept tripping the GFCI. I pulled a ground thru the conduit from the panel, connected it inside the box, and all the problems went away. Before connecting, I was reading > 40v between panel ground and earth ground at the spa pad. I came back to service the spa later when it was dry (relay problem in the unit it turns out), and I re-tested got 0v. I was not the electrician just a swimming pool company tech that worked on pumps and such but I saw stuff like this all the time, this was by far the worst, I think the homeowner ran the service to the spa, but it was definitely not a problem when the ground was dry.
That is a different issue.
It comes from all the induction motors and resistance heaters in contact with water.
Its why swimming pools require specific grounding rules in the code book.
timselectric
If I can do it, you can do it.
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Swimming pools require extra grounding connections because everything is more conductive when wet.(including people)
42OhmsPA
What's in a title?
Excellent info in this thread and great discussion.
So many years back when I thought solar was dumb (I know, shock me) and I wired in my pole garage I added an additional ground round... I'm debating if I should disconnect it.
I'll try to describe the current state.
Grid connection / meter to house and main grounding rod, 200A breaker and N/G bond. Run to main load panel (with 4 wire aluminum feeder) which feeds grid to AIO (grid output breaker is open most of the year) . AIO out to subapnel 1 which feeds the garage and upstairs panel. The garage panel feed is also 4 wire AL and has its own ground rod. Ehh that's confusing let me draw a diagram. (hopefully my chicken scratch is legible)
If it matters the upstairs panel was originally the main panel, I rewired the grid feed to the main load panel when I installed the AIO.
So many years back when I thought solar was dumb (I know, shock me) and I wired in my pole garage I added an additional ground round... I'm debating if I should disconnect it.
I'll try to describe the current state.
Grid connection / meter to house and main grounding rod, 200A breaker and N/G bond. Run to main load panel (with 4 wire aluminum feeder) which feeds grid to AIO (grid output breaker is open most of the year) . AIO out to subapnel 1 which feeds the garage and upstairs panel. The garage panel feed is also 4 wire AL and has its own ground rod. Ehh that's confusing let me draw a diagram. (hopefully my chicken scratch is legible)
If it matters the upstairs panel was originally the main panel, I rewired the grid feed to the main load panel when I installed the AIO.
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timselectric
If I can do it, you can do it.
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And Hopefully removed the N/G bond from the upstairs panel.
It's still required per the current code.
(I would remove it)
42OhmsPA
What's in a title?
Thank you Tim.
I need to pull that panel cover off andcheck re-torque the connections anyway they are overdue for PM.
Yes, no N/G bonds exist besides the main grid feed entrance.
Easy enough (required not necessary...)
I need to pull that panel cover off and
FilterGuy
Solar Engineering Consultant - EG4 and Consumers
I am Schizophrenic (and so am I) so I will argue with myself.
The rules around grounding say that anything that could act like a grounding electrode, is a grounding electrode and must be tied into the grounding system. It also says any exposed metal must be tied into the grounding system. Both of these are reasonable requirements, even in the case of a 2nd building. Consequently, if the 2nd building is much more than a wooden shed sitting on the ground, there will be earth grounding regardless of the presence of a dedicated earth grounding electrode. Consequently, it may not matter much if the code requires a dedicated electrode. However, one should still pay attention to how the grounding conductor of the feeder ciricuit to the building is routed.
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What’s the difference between 2nd , and auxiliary rods? 2nd would be 1 at house, and one at second building? Auxiliary would the the 2nd of 2 ground rods (connected together) forming the grounded electrode?Another nice video from Mike Holt.
Auxilary grounding rods are not required but there is a rule that states there are no requirements on an auxiliary ground e;ectrodes. At one point in the video, he talks about CAT 5 wires and 10 penny nails for the auxiliary grounding electrode.
It has taken several years but we are starting to see both professionals and DIYrs wake up to the fact that auxiliary grounding electrodes are 1) not required and 2) not recommended.
Having said that, I am still a little uncomfortable with the code requirement for a second (not auxiliary) grounding electrode for separate buildings. I would love to see the rationale for this as well as a multi-year study of a bunch of instances where this is not done. The good news is that with just a little planning the 2nd electrode can be set up with the path to the first electrode only going through breaker boxes....but even breaker boxes are starting to get a lot of electronics in them.
You recommend (if I recal) the array EGC connected to the main GEC right?
Tim has stated anything connected to grounding system becomes part of the grounding system (but I don’t know if Tim recommends that or not).
Wouldn’t it be better to connect each EGC to a central ground busbar, instead of connecting to other metal (rather than grounding to inverter)
If all metal gets connected together than why does it matter?
FilterGuy
Solar Engineering Consultant - EG4 and Consumers
T
The code requires grounding electrodes connected in at the first means of disconnect at the house and each of the other building.
The code allows but does not require grounding electrodes elsewhere in the system. As an example generator companies used to require grounding electrodes at the generator even though the NEC does not require them. These non-required electrodes are called auxiliary electrodes by the NEC and the NEC specifically says that there are no requirements on an auxiliary grounding electrode. (a 10-penny nail in a flower pot could be called an auxiliary grounding electrode).
Good Question.
The code requires grounding electrodes connected in at the first means of disconnect at the house and each of the other building.
The code allows but does not require grounding electrodes elsewhere in the system. As an example generator companies used to require grounding electrodes at the generator even though the NEC does not require them. These non-required electrodes are called auxiliary electrodes by the NEC and the NEC specifically says that there are no requirements on an auxiliary grounding electrode. (a 10-penny nail in a flower pot could be called an auxiliary grounding electrode).
FilterGuy
Solar Engineering Consultant - EG4 and Consumers
I recommend routing the PV EGC directly to the main breaker box where the Grounding Electrode Conductor ties in. It would be better to route it directly to the grounding electrode, but I don't know if inspectors would allow it.
I’m still confused. 2nd rods,and aux rods are the same thing?
Also….. ground rod at array, and rod at main service is not a good idea….. but 2nd rod at 2nd building (let’s say detached garage sub panel is needed…….
Isn’t that the same situation?
