A good example of why not to use a ground rod at a generator. Then WHY drive a ground rod at a shed or dettached garage subpanel? A lightning strike near the shed would bring the charge to the house service panel, via the ground rod and equipment grounding conductor.
The purpose of the auxiliary grounding electrode at an outside generator or lighting pole is to help mitigate damage from a lightning event. I sort of agree with Mike that it may not work as designed by the engineers, but that is the purpose. There are a lot of "White Papers" showing engineering studies in regards to this topic.
I am confused just as All Day Jack. On one video it was showed the outdoor panel is connected to the ground rod to direct the lightning current (caused by induction) to the ground. On this video, it was shown that the lightning current can go back to the building if the generator is grounded. I am concerned because my facility has many control systems worth millions dollars. It seems to me that if I install a ground rod, the lightning current will flow into the building through the ground rod, if I don’t install the ground rod , the equipment inside the building will be damaged or fire through induction. Either way I get trouble.
With the auxiliary electrode and a generator. I get it. We don't want it. But the casing of that generator is grounded locally (or maybe not) and it will develop very high voltage in reference to the rest of the system. Now we can have electronics or insulation failing in the generator and there is nothing we can do about it. An SPD will do nothing because it's connected to system ground (and we want to keep it that way to not introduce this local high potential into our system ground). Is there no way to protect our generator? (in my case a ground mounted Pv array rather than a generator, but whether it's a generator, a separate building or a pv array we have the same problem). How to surge protect when we have difference in ground potentials?
The generator and PV system (and all other electrical equipment) is connected to the circuit equipment grounding conductor and 'never' connected to earth ground. Therefor there will never be any difference of potential on any metal parts of electrical equipment that is wired in accordance with the NEC..
Since bonding to the water and gas pipes is required, wouldn't that have the same effect as the example presented with the nearby lightning strike and the ground rod? Also, how does the "whole-house surge protection" rating help, when the ground potential dramatically increases during a lightning strike? The same for lighting protection for metal roofing.
Since everything is bonded together inside, there is no difference in potential; so no problem. When all is bonded together, voltage does not rise between metal parts. Why would anybody provide lighting protection for a metal room?
@@MikeHoltNEC Thank you very much, Mike for your prompt reply and information, and for all your help. I really appreciate it. Regarding metal roof lighting protection, somehow the topic came out on the specs for a project where solar panels were going to be installed on top of the metal roof.
@@MikeHoltNEC question if I have a rigid conduit in the ground and it needs repair can I attach pvc adapter to ridgid convert conduit to pvc and then before coming back out of the ground convert back to ridgid?
Wouldn't the type of transfer switch used to connect a generator to a home make it a SDS or not? For example a transfer switch that switches the neutral wire would make the generator a SDS. Is this why the generator manual may say to use a ground rod, because the SDS would be factored on what type of transfer switch that is used?
Yes, that’s correct. If the neutral is disconnected from the primary service, then it’s a separately derived system, and it needs a grounding electrode.
What that's a 'deep' question. But the short answer is that if the transfer switch switches the neutral, then the generator will be a separately derived system and it must be bonded and grounded in accordance with 250.30(A). If the transfer switch does not switch the neutral, then the generator is not a separately derived system and the generator must not have the neutral bonded to the metal parts and no grounding is required. So don't follow 250.30(A).
I have a question, im installing a service of 200A by roadside, like 50ft away from the main house and installing 2 ground rods at the first point of disconnect which technically it is the main panel. Can i do a ufer grounding over at the building on the first floor using the rebar grid since the main panel will be upstairs?
Some earth's are joined to neutral at cut out. If neutral becomes damaged on way out of property and earth is also disconnected. Hence ground rod provides earth.
![Identification of Equipment Grounding Conductors [250.119, 2020 NEC]](http://i.ytimg.com/vi/JFYd_6SHIkA/mqdefault.jpg)
![Identification of Equipment Grounding Conductors [250.119, 2020 NEC]](/img/tr.png)
![Grounding, Objectionable Current [250.6, 2020 NEC]](http://i.ytimg.com/vi/skX9XI3de5U/mqdefault.jpg)
![Grounding, System and Equipment [250.4, 2020 NEC]](http://i.ytimg.com/vi/lyD6gzEze68/mqdefault.jpg)
![Ground Rods at Metal Poles, NEC 2020 - [250.4(A)(5)], (25min:09sec)](/img/n.gif)
Outstanding! Thanks for the updated video.
You are most welcome.
RIP headphone users at 4:55 and 5:20, lol...
A good example of why not to use a ground rod at a generator. Then WHY drive a ground rod at a shed or dettached garage subpanel? A lightning strike near the shed would bring the charge to the house service panel, via the ground rod and equipment grounding conductor.
But there is no ten thousand dollar electronic equipment between the ground rods.
The purpose of the auxiliary grounding electrode at an outside generator or lighting pole is to help mitigate damage from a lightning event. I sort of agree with Mike that it may not work as designed by the engineers, but that is the purpose. There are a lot of "White Papers" showing engineering studies in regards to this topic.
I am confused just as All Day Jack. On one video it was showed the outdoor panel is connected to the ground rod to direct the lightning current (caused by induction) to the ground. On this video, it was shown that the lightning current can go back to the building if the generator is grounded. I am concerned because my facility has many control systems worth millions dollars. It seems to me that if I install a ground rod, the lightning current will flow into the building through the ground rod, if I don’t install the ground rod , the equipment inside the building will be damaged or fire through induction. Either way I get trouble.
Is this part of you dvds?
Yep
With the auxiliary electrode and a generator. I get it. We don't want it. But the casing of that generator is grounded locally (or maybe not) and it will develop very high voltage in reference to the rest of the system. Now we can have electronics or insulation failing in the generator and there is nothing we can do about it. An SPD will do nothing because it's connected to system ground (and we want to keep it that way to not introduce this local high potential into our system ground). Is there no way to protect our generator? (in my case a ground mounted Pv array rather than a generator, but whether it's a generator, a separate building or a pv array we have the same problem). How to surge protect when we have difference in ground potentials?
The generator and PV system (and all other electrical equipment) is connected to the circuit equipment grounding conductor and 'never' connected to earth ground. Therefor there will never be any difference of potential on any metal parts of electrical equipment that is wired in accordance with the NEC..
Hold on a minute did they actually be sleeve a grounding electrode going through concrete?
?
Since bonding to the water and gas pipes is required, wouldn't that have the same effect as the example presented with the nearby lightning strike and the ground rod? Also, how does the "whole-house surge protection" rating help, when the ground potential dramatically increases during a lightning strike? The same for lighting protection for metal roofing.
Since everything is bonded together inside, there is no difference in potential; so no problem. When all is bonded together, voltage does not rise between metal parts. Why would anybody provide lighting protection for a metal room?
@@MikeHoltNEC Thank you very much, Mike for your prompt reply and information, and for all your help. I really appreciate it. Regarding metal roof lighting protection, somehow the topic came out on the specs for a project where solar panels were going to be installed on top of the metal roof.
Generac says we dont put in ground rod in
They do require a ground rod at the automatic transfer switch as it id the first place of disconnect.
Generac 'does not' require any grounding or bonding. This is under the scope of the NEC.
My coworkers argue that having a ground rod is a safety feature to prevent shock in case of a short or a ground fault. Is this the case?
They ground all equipment to ground rod.
Watch this video, to understand why this statement is 100% false.
@@MikeHoltNEC question if I have a rigid conduit in the ground and it needs repair can I attach pvc adapter to ridgid convert conduit to pvc and then before coming back out of the ground convert back to ridgid?
@@Jinxo-md2jl Post questions not related to this video on MikeHolt.com/Forum
Wouldn't the type of transfer switch used to connect a generator to a home make it a SDS or not? For example a transfer switch that switches the neutral wire would make the generator a SDS. Is this why the generator manual may say to use a ground rod, because the SDS would be factored on what type of transfer switch that is used?
Yes, that’s correct. If the neutral is disconnected from the primary service, then it’s a separately derived system, and it needs a grounding electrode.
Why do i have to bond to a main water line?
See 250.104.
What would make a generator a separately derived system vs. not?
What that's a 'deep' question. But the short answer is that if the transfer switch switches the neutral, then the generator will be a separately derived system and it must be bonded and grounded in accordance with 250.30(A). If the transfer switch does not switch the neutral, then the generator is not a separately derived system and the generator must not have the neutral bonded to the metal parts and no grounding is required. So don't follow 250.30(A).
@@MikeHoltNEC Hi Mike, how about a Solar systems of any type? Are they SDS?
I have a question, im installing a service of 200A by roadside, like 50ft away from the main house and installing 2 ground rods at the first point of disconnect which technically it is the main panel. Can i do a ufer grounding over at the building on the first floor using the rebar grid since the main panel will be upstairs?
Anybody notice the light out on the street go out after the lightning strike?
I'll look at that...
Yep, I noticed it. The light on the outbuilding and the globe light both appear to blow out during the strike.
*Lightning striking tree and exploding it into a million pieces* "Damn nature! You scary!"
Some earth's are joined to neutral at cut out. If neutral becomes damaged on way out of property and earth is also disconnected. Hence ground rod provides earth.
And that doesn’t provide an effective ground fault current path. Fault current thru earth won’t trip ocpd