[Huck]

My question regarding disconnects to a main service was simply this:
Is there a limit of total disconnects that can be in series on the load side of the main service disconnect? This question was not answered.


You have stated many times that a grounding electrode is only allowed to be bonded to the grounded conductor at the main service disconnect. Are you citing 250.24(A)(5) Load Side Grounding Connections as your basis that no other bond of the grounding conductor shall be made to a grounding electrode except at the main service disconnect?

If so please advise regarding your opinion of 250 Section III, 250.50 Grounding Electrode System which states "all grounding electrodes ...that are present at each building or structure served shall be bonded together to form a bonding electrode system" Is this not stating more than one electrode in multiple locations bonded together?

I still do not find a specific line of code that DOES NOT ALLOW more than one grounding electrode to be attached to the grounded conductor at a location distant from the service entrance, except possibly 250.24(A)(5)? Please cite it. Just reading 250.24 in totality does not answer the question... Again please cite the line of code that DOES NOT ALLOW more than one grounding electrode.

The multiple grounding electrode question is the only one still on the table between me and the "new electrician who appears very competent" and the commercial company responsible for the genset/ATS install. A schematic drawn by a P.E. for the company shows a grounding electrode at the meter service entrance connected to the grounding conductor which runs to the house and a grounding electrode at the house connected to the same grounding conductor. They both have signed off on the install. So who is right??

Can an additional grounding electrode be placed at a distant point along the grounding conductor or not. Cite the exact code line that I can show them.

P.S. I also contacted the generator dealer (CAT Olympian) and their guy said in most installations they installed their gensets they saw a grounding conductor bonding the enclosure/case/block of the genset (separate from neutral) and also a grounding electrode attached to the same point on the genset in a non separately derived genset/ATS intall.

Thanks again as always...

Huck

[tkrussell]

OK now looks like I got you thinking, reading, and asking better questions. Sure I get tunnel vision when answering a question about a topic, I need to see other perspectives or questions worded differently.

I may bounce around a bit here.

And not going to do any fancy formatting.

Just keep in mind the code will state something one way, either shall/may or shall not/may not, but not say both.

Also keep in mind there are different scenarios that cannot be mixed up.

You situation is falling under 250.24, and seems there is some blending with 250.32. A system needs to be designed with one or the other, or one up to one building and can be another to other buildings.

But I am drifting here, let me try to do some of these in order.


Is there a limit of total disconnects that can be in series on the load side of the main service disconnect?

No, no limit to disconnect switches downstream of the "main" service disconnecting means, which will be the one or up to six, grouped together at the point of service directly from the utility. From that point on, there can be as many switches as desired in the feeder line.


You have stated many times that a grounding electrode is only allowed to be bonded to the grounded conductor at the main service disconnect. Are you citing 250.24(A)(5) Load Side Grounding Connections as your basis that no other bond of the grounding conductor shall be made to a grounding electrode except at the main service disconnect?

Exactly.

This is what I thought you were focusing on, and the most important point I have been trying to make. Only at the first "service disconnecting means" which is also an overcurrent protection device, can the grounded (neutral) conductor be grounded by being connected to the grounding electrode conductor and electrode.

From this point on the two cannot meet.

If so please advise regarding your opinion of 250 Section III, 250.50 Grounding Electrode System which states "all grounding electrodes ...that are present at each building or structure served shall be bonded together to form a bonding electrode system" Is this not stating more than one electrode in multiple locations bonded together?

OK so from the main, there may be one wire, goes to a ground rod or rods at that point, usually nearby the meter or disconnect. Or there may be other wires that come from other electrodes, or the other electrodes are connected together "bonded" out in the field.

I can have one wire go to a rod, the to a water line, then to building steel, or I can have have a wire coming back from each, to the main switch. This will be consider as the system grounding that must be established.

This has been for your situation, now onto another per 250.32, in those cases that a service in one building feeds another building.

So, for example, and maybe this is where some confusion is coming from, say I have the main service in my home, and then I have a barn for live stock, and then I have a garage for my machinery, I drive a rod and connect to the main switch to ground the neutral, my system ground has been established. A PVC conduit goes from house to barn, AND there is no other metal line from house to barn, such as a water line, telephone wire, etc, I only need to run three wires (2 hots and 1 neutral). I now must bond the neutral AND the ground AND drive a ground rod at the barn, and if the same circumstances is with the garage, the same is done.

I still do not find a specific line of code that DOES NOT ALLOW more than one grounding electrode to be attached to the grounded conductor at a location distant from the service entrance, except possibly 250.24(A)(5)? Please cite it.

Cite what?

Just reading 250.24 in totality does not answer the question...

It has to answer the question. This is why it takes so long to understand how to understand this damn NEC. There are people that only teach people how to read it, and understand it.

See to me, and of course many others, just to be clear this is not just my personal interpretation or opinion, 250.24(5) states it very clear, "A grounding connection SHALL NOT be made to any GROUNDED circuit conductor on the load side of the service disconnecting means, EXCEPT as otherwise permitted in this article."

Then the Fine Print Note, refers to 250.32, which I did not apply to your situation, but does in my house/barn/garage example.

250.24 is short and to the point, the FPN to 250.32 is where confusion starts.

Again please cite the line of code that DOES NOT ALLOW more than one grounding electrode.

My intention on this was no other grounding electrodes connect to the grounded conductor at the house, once the system was grounded at the main switch.

The multiple grounding electrode question is the only one still on the table between me and the "new electrician who appears very competent" and the commercial company responsible for the genset/ATS install. A schematic drawn by a P.E. for the company shows a grounding electrode at the meter service entrance connected to the grounding conductor which runs to the house and a grounding electrode at the house connected to the same grounding conductor.

I think the confusion is the two buildings, first the one for the genset, and then the house. I earlier highlight "supplied", and my take is the shed is only to house the genset, there are no panelboards or branch circuits, and this was to eliminate 250.32 from being considered, which addresses different scenarios, and must be determined clearly before deciding what method should be done. Only one of the scenarios of 250.32 should apply, not a blend.


So the PE is referring to 250.32(B)(1), and considering the shed to be "supplied" , and this being the main service, and then your home is the remote building,with an equipment ground, and yes, if this is how he is interpreting your installation, then at the house a rod MUST be driven, and only connect to the grounding , not the grounded.


P.S. I also contacted the generator dealer (CAT Olympian) and their guy said in most installations they installed their gensets they saw a grounding conductor bonding the enclosure/case/block of the genset (separate from neutral) and also a grounding electrode attached to the same point on the genset in a non separately derived genset/ATS intall.

First, gensets must be grounded via an electrode if they require it in their manual, does not need one if they don't require it, one can be there if desired, again, only to the grounding, not the grounded.

First off, since I took the shed as not being "supplied", then no other grounding of the equipment ground is needed. Initially trying to keep things simple without getting into all the different exceptions,scenarios,situations. Pick a method and stick with it, giving too many options can end up getting the neutral grounded at other locations, and that cannot happen.

Plain, simple systems do not need additional grounding rods remote from the main service, yes there are exceptions, but only if 250.32 applies, which usually does not, and I did not apply to yours. Seems the PE did, and as long as the grounded conductor does not get connected to the grounding, as stated in 250.24 and reiterated in 250.32(B)(1).

Let me add, that if 250.32(B)(1) is being used to justify the rod at the house, then there must be one at the gear in the shed also, in addition to the one at the main service disconnect, since it seems that the shed is being considered as being "supplied".

Once you leave 250.24 and enter 250.32, you must keep your wits sharp, as this is where problems can occur.So, depending on how your system is viewed, either one of us is right. I try to keep things simple, once they get beyond simple, then details really are important.

Thanks again as always...

Your welcome, I really enjoy this discussion off the beaten path.

[Huck]

Thanks very much TK, we are ALL on the same sheet of music now. I hope you have appreciated my attention and perserverance to get to a united answer. I appreciate your patience. That is kind of what engineers are good for, perserverance, but not much grunt work!

Per your help, the initial electrician was released, the new electrical contractors are stripping every wire out of my new house (there were other problems not worth mentioning) and rewiring per their standards, code and inspection requirements (even if not inspected), and everyone understands each other on this damn grounding/bonding issue in this special application.

The plan now as it stands is to place two additional grounding electrodes. Referring to the layout prior, one at the disconnect at the entrance to the dwelling and another at the genset on the other side of the building supporting the main disconnect/meterbase, along with the original grounding electrode as shown on layout. All interconnected to the grounded conductor (properly sized), but forever isolated from the system neutral conductor.

In this exact, specific application, as described in the most finite details over the last few days, with magnifiying examination of the 2005 NEC, do you agree with this final conclusion?? I am anxiously awaiting your final answer?? :) :) :) :D :D :D

Huck

[tkrussell]

As per NEC 250.32(B)(1), looks great.

OK now you have piquéd my interest. You can't just leave me hanging here.

All the wire the first contractor installed inside is being removed?

What the heck did he do? A first year apprentice knows how to wire a house!

Explanation, and pictures if possible is in order. We all need a laugh by now.

[Huck]

I will get you a couple of example photos tomorrow. Mostly workmanship and "if inspected would not pass" issues and just plain code violation issues.

1) Started with poor knowledge of proper application of code principles of 4-wire systems per this forum topic. You saw the main panel wiring that I posted prior.
2) Early on I questioned placing a 100A subpanel in my attic without adequate access to supply all my light circuits. Not acceptable to new contractors, required major rewire.
3) Wrong size volume work boxes to meet surrounding county code.
4) No permanent fastening of circuit wires to studs per code
5) 3-wire feed to subpanel in attic attached to 4-wire main panel
6) Current electrical contractors could rip out all standard circuit wiring and redo per their conventions by the time they could figure out the logic of each unmarked wire in the house. Cost was less to builder to just redo versus a rework existing. No cost to me.
7) Using proper load calculations and reusing standard 12g wire, they have not had to provide any additional wire but I have a greatroom floor full of excess wire from such a poor job of calculating standard loads on the circuits. 100A subpanel not needed now.
8) I should have questioned him earlier when I saw the first few work boxes nailed to studs that looked like they came from a 5-gallon bucket full of rusty water in the back of his truck. This is a custom home, not a hunting camp!
9) Some wire was pulled so tight that it pulled hard kinks in loops of wire.

The new company is so confident with the entire project including the genset/ATS I will not have to use the commercial electricians to interface at the house. The new contractors worked today and have rewired 3/4 of the rough-in. It looks great!

A talk with my very reputable building contractor revealed he had been compensating for deficiences of the electrician the past year. His last job did pass inspection but I understand the inspection process in that county is pretty lax.

I am back to enjoying building a house. Again thanks, you gave me support of the code to require my builder get his own second opinion of the situation.

I will try to get a souple of photos tomorrow.

Regards,
Huck