Grounding, Auxiliary Grounding Electrode [250.54, 2020 NEC]

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4 жыл бұрын

250.54 Grounding, Auxiliary Grounding Electrode - www.MikeHolt.com/bonding. Are auxiliary grounding electrodes required by the NEC? Do they serve any real purpose? The answer(s) is/are, no. Find out why and how they might just do more harm than good in this compelling discussion with our panel of experts!
This video is extracted from Mike Holt's 2020 Bonding and Grounding Textbook and DVD program, for more information visit www.MikeHolt.com/bonding or call 888.632.2633.
For almost 50 years, Mike Holt Enterprises has been providing quality electrical Code training to help electrical professionals learn the Code, prepare for exams, and improve their electrical knowledge. Visit www.MikeHolt.com for exam preparation tips and training, instructor and curriculum support, continuing education options, free videos and graphics, and so much more.

Пікірлер: 36

@atomicdmt8763 3 жыл бұрын

Outstanding! Thanks for the updated video.

@MikeHoltNEC 3 жыл бұрын

You are most welcome.

@BrentFreyEsq 4 жыл бұрын

RIP headphone users at 4:55 and 5:20, lol...

@alldayjack4830 4 жыл бұрын

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.

@MikeHoltNEC 4 жыл бұрын

But there is no ten thousand dollar electronic equipment between the ground rods.

@pierrebelarge892 3 жыл бұрын

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.

@epower7152 2 жыл бұрын

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.

@MyBluetti Жыл бұрын

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?

@ivanbroce1181 3 жыл бұрын

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.

@MikeHoltNEC 3 жыл бұрын

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?

@ivanbroce1181 3 жыл бұрын

@@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.

@misfitsman805 3 жыл бұрын

*Lightning striking tree and exploding it into a million pieces* "Damn nature! You scary!"

@MrKen59 2 ай бұрын

What would make a generator a separately derived system vs. not?

@MikeHoltNEC 2 ай бұрын

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).

@ominguti6345 Ай бұрын

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?

@MikeHoltNEC Ай бұрын

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..

@garyhoffman4495 9 ай бұрын

Hold on a minute did they actually be sleeve a grounding electrode going through concrete?

@MikeHoltNEC 9 ай бұрын

@joenavarro9317 3 жыл бұрын

Is this part of you dvds?

@MikeHoltNEC 2 жыл бұрын

Yep

@Jinxo-md2jl 3 жыл бұрын

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?

@Jinxo-md2jl 3 жыл бұрын

They ground all equipment to ground rod.

@MikeHoltNEC 3 жыл бұрын

Watch this video, to understand why this statement is 100% false.

@Jinxo-md2jl 3 жыл бұрын

@@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?

@MikeHoltNEC 3 жыл бұрын

@@Jinxo-md2jl Post questions not related to this video on MikeHolt.com/Forum

@RHP2024 3 жыл бұрын

Generac says we dont put in ground rod in

@Sparkeycarp 2 жыл бұрын

They do require a ground rod at the automatic transfer switch as it id the first place of disconnect.

@MikeHoltNEC 2 жыл бұрын

Generac 'does not' require any grounding or bonding. This is under the scope of the NEC.

@nyrbn 3 жыл бұрын

Why do i have to bond to a main water line?

@MikeHoltNEC 3 жыл бұрын

See 250.104.

@Sparkeycarp 2 жыл бұрын

Anybody notice the light out on the street go out after the lightning strike?

@MikeHoltNEC 2 жыл бұрын

I'll look at that...

@TheCapt Жыл бұрын

Yep, I noticed it. The light on the outbuilding and the globe light both appear to blow out during the strike.

@dannymai4874 11 ай бұрын

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?

@joegolden5214 3 жыл бұрын

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.

@djhatton6858 2 жыл бұрын

And that doesn’t provide an effective ground fault current path. Fault current thru earth won’t trip ocpd