ground rods

[M. D.]

I think what I remember :grin: is that you will find the shorter marking on panels that allow some combination of circuit breakers with or with out the use of handle ties that when the board is filled equal not more than six throws...

 

[zog]

I always just prove my resistance!:grin: Welcome to the forum Nuvi!!

And how do you do that?

 

[Smart $]

The panel would have to be service rated without a main and while I have seen such panels for large commercial use I don't think you will find a 'load center' that has a service rating without a main. Of course you could use a service rated disconnect ahead of the main lug panel. :smile:

Hmmm... what exactly is meant by an outbuilding in the exception to 250.36??? Is it the same as what in days past what was referred to as an outhouse???? Or does it mean any buiding which is not the primary dwelling building of the residency and not a garage?

Anyway, depending on the interpretation of the Exception, the disconnecting means may not have to be service-rated.

 

[220/221]

So almost anything is a structure.

In my area, the AHJ's use a more conservative definition of the word.


We are allowed to install pool panels (for example) without ground rods. They are usually installed on a couple pieces of rigid driven into the ground and attached with pipe clamps. I have attached a few to block fences and it wasn't considered a structure.

I think "structure" refers to something that could attract a lightning strike, thus requiring ground rods.

 

[Dennis Alwon]

I think "structure" refers to something that could attract a lightning strike, thus requiring ground rods.

I am confused
when you stated the above and then stated this

They are usually installed on a couple pieces of rigid driven into the ground and attached with pipe clamps

Will this not attract lightning? Of course you are in AZ

 

[220/221]

It's like 36" off the ground so.....no.

 

[tom baker]

Sub panel is not an NEC term.
But if you run a feeder to a separate building, a grounding electrode system is required.
The requirement for this comes from 250.4(A)(1), for protection from lightning. Lightning will strike a building with or without electrical power, and it does not matter if its a 40 ampere feeder or 400 ampere. Yes it would be tied in with the ground system at the house, but lightning seeks a direct path to earth, the house ground, due to the distance would present a huge instantaneous voltage drop of perhaps 50,000 edit volts (not amperes) + so it just would not be effective.

The feeder must contain an equipment grounding conductor, the neutral can not be regrounded, this was effective in the 2008 NEC. And even if the neutral conductor was regrounded, a grounding electrode system is required, and has been required for much more than 25 years.

And just a polite suggestion, you would greatly benefit from attending Mike Holts Grounding vs Bonding seminar, or the DVD, or his text.

 

[Dennis Alwon]

It's like 36" off the ground so.....no.

Lee Trevino got hit by lightning and he is not much more than 36" tall. He also doesn't have rods in the ground that he is connected to.

 

[iwire]

Anyway, depending on the interpretation of the Exception, the disconnecting means may not have to be service-rated.

I agree. :smile:

 

[iwire]

In my area, the AHJ's use a more conservative definition of the word.

It is not up to the AHJ to define the word structure, the NEC has done that for them. :smile:

We are allowed to install pool panels (for example) without ground rods. *1 They are usually installed on a couple pieces of rigid driven into the ground and attached with pipe clamps. *2 I have attached a few to block fences and it wasn't considered a structure. *3

*1 Those pool panels are NEC required to have grounding electrodes if they are installed separate from the structure that supplies them.

*2 That panel and RMC combination is a structure per the NEC definition.

*3 The inspector did not enforce the NEC as written. That appears to be common in your area. :grin:

I think "structure" refers to something that could attract a lightning strike, thus requiring ground rods.

We can all think whatever we want but we have to follow the NEC definitions when they are provided.:smile:

 

[hillbilly1]

I think "structure" refers to something that could attract a lightning strike, thus requiring ground rods.

Ground rods or grounding electrode systems are not just for reducing the effects of lightning, they also help miminize overvoltage from utility malfunctions, such as downed wires or other overvoltage situations.:smile:

 

[tom baker]

The term 'service rated" has been used which is not correct.
Service equipment is rated Suitable for Use as Service Disconnect" meaning it has a main bonding jumper that can be installed, allowing to be used as a "sub-panel, or surface-panel, where the neutral is not allowed to be bonded. "Suitable for use a service disconnect only" means the equipment can only be used where the neutral is bonded, and can't be used as a
"sub-panel, or surface-panel, or feeder panel.
A surface panel is one that is not used on a sub.
I make the above comment to clarify we get into trouble when we use terms that are not defined in the NEC, for example see the definition of Structure.

 

[zog]

Lee Trevino got hit by lightning and he is not much more than 36" tall. He also doesn't have rods in the ground that he is connected to.

He was quoted after that, at another tourney with storms in the forcast, as saying he plans on using a 1 iron, because even God can't hit a 1 iron.

 

[ItsHot]

And how do you do that?

Two pieces of coat hanger!:grin:

 

[zog]

Two pieces of coat hanger!:grin:

And then....?

 

[Smart $]

The term 'service rated" has been used which is not correct.
Service equipment is rated Suitable for Use as Service Disconnect" meaning it has a main bonding jumper that can be installed, allowing to be used as a "sub-panel, or surface-panel, where the neutral is not allowed to be bonded. "Suitable for use a service disconnect only" means the equipment can only be used where the neutral is bonded, and can't be used as a
"sub-panel, or surface-panel, or feeder panel.
A surface panel is one that is not used on a sub.
I make the above comment to clarify we get into trouble when we use terms that are not defined in the NEC, for example see the definition of Structure.

Good point!

However, the NEC does not distinguish between the different types of service disconnecting means as you state, which rather is a condition of the equipment's listing. The NEC, at best, simply states it be suitable for the prevailing conditions... and even that is only under Servicing Disconnecting Means in 230.70.

225.36 rather vaguely states "suitable for use as service equipment".

Though "service-rated" may not be an NEC defined term, I believe it is sufficient for the discussion at hand. It is up to whoever orders/buys the disconnect for the specific application to know the difference.

 

[iwire]

The term 'service rated" has been used which is not correct.
Service equipment is rated Suitable for Use as Service Disconnect"

I believe the correct term is for Suitable for use as service equipment.

 

[mack]

ground clamps on ground rod

ground clamps on ground rod

I understand only one ground conductor on a ground clamp . However in the area we need to drive a ground rod there's alot of under ground conduit and we will surely hit one . I plan on grounding to the building steel but I was wondering is it legal to attach another ground clamp to the existing ground rod.

Thanks for any feed back
Mack D

 

[infinity]

I understand only one ground conductor on a ground clamp . However in the area we need to drive a ground rod there's alot of under ground conduit and we will surely hit one . I plan on grounding to the building steel but I was wondering is it legal to attach another ground clamp to the existing ground rod.

Thanks for any feed back
Mack D

Yes you can have multiple clamps on a ground rod:

 

[mack]

these are two completely separate systems . each as its own 75 kva Xform. In a mech. room with a great deal of underground in the slab. I really don't want to drill for another ground rod.