Rods

[Dennis Alwon]

Is there any guidance on the installation of a ground rod? Should it be vertical (plumb) or can it be driven at an angle? If at an angle, what is appropriate? If there is solid rock say 3 or 4 feet below ground level, can the rod be driven at an angle to be completely buried in the dirt before contacting the solid rock... say at an angle some where between 30 and 60 degrees?

Yes there is guidance. Look at 250.53(G)

(G) Rod and Pipe Electrodes. The electrode shall be installed
such that at least 2.44 m (8 ft) of length is in contact
with the soil. It shall be driven to a depth of not less than
2.44 m (8 ft) except that, where rock bottom is encountered,
the electrode shall be driven at an oblique angle not
to exceed 45 degrees from the vertical or, where rock bottom
is encountered at an angle up to 45 degrees, the electrode
shall be permitted to be buried in a trench that is at least
750 mm (30 in.) deep. The upper end of the electrode shall be
flush with or below ground level unless the aboveground end
and the grounding electrode conductor attachment are protected
against physical damage as specified in 250.10.

 

[John120/240]

Is there any guidance on the installation of a ground rod? Should it be vertical (plumb) or can it be driven at an angle? If at an angle, what is appropriate? If there is solid rock say 3 or 4 feet below ground level, can the rod be driven at an angle to be completely buried in the dirt before contacting the solid rock... say at an angle some where between 30 and 60 degrees?

There is no limitation on what angle that you drive your ground rod. When you encounter rock, dig a trench as long as your ground rod then put a right angle bend on the rod long enough to reach grade. The Main thing is that you have the whole length of your rod in contact with earth.

 

[petersonra]

There is no limitation on what angle that you drive your ground rod. When you encounter rock, dig a trench as long as your ground rod then put a right angle bend on the rod long enough to reach grade. The Main thing is that you have the whole length of your rod in contact with earth.

250.53(G)
(G) Rod and Pipe Electrodes. The electrode shall be installed
such that at least 2.44 m (8 ft) of length is in contact
with the soil. It shall be driven to a depth of not less than
2.44 m (8 ft) except that, where rock bottom is encountered,
the electrode shall be driven at an oblique angle not
to exceed 45 degrees from the vertical or, where rock bottom
is encountered at an angle up to 45 degrees, the electrode
shall be permitted to be buried in a trench that is at least
750 mm (30 in.) deep. The upper end of the electrode shall be
flush with or below ground level unless the aboveground end
and the grounding electrode conductor attachment are protected
against physical damage as specified in 250.10.

While technically you are correct that the code does not give any requirement for an angle at which a rod is driven, there is a requirement that it be driven at least 8 feet deep.

Personally, I do not see anything in the code that actually requires performance testing by the installer for ground rod installation. And given how unimportant it is, I just don't see that it makes any real difference.

OTOH, pounding in a second rod costs very little above just doing a single rod. At some point one's time arguing over it is worth more than the little bit of cost associated with just putting in a second rod.

 

[Pharon]

While technically you are correct that the code does not give any requirement for an angle at which a rod is driven, there is a requirement that it be driven at least 8 feet deep.

Huh? It says right there about angles in the section you cited -- that it's not to exceed 45 degrees.

 

[don_resqcapt19]

Is there any guidance on the installation of a ground rod? Should it be vertical (plumb) or can it be driven at an angle? If at an angle, what is appropriate? If there is solid rock say 3 or 4 feet below ground level, can the rod be driven at an angle to be completely buried in the dirt before contacting the solid rock... say at an angle some where between 30 and 60 degrees?

See 250.53(G).

 

[petersonra]

Huh? It says right there about angles in the section you cited -- that it's not to exceed 45 degrees.

Read carefully. The angle stated only applies where you cannot get the 8 feet depth.

IMO, if you had a long enough rod, you could drive it at any angle you want as long as it ends up 8 feet deep.

 

[kwired]

Read carefully. The angle stated only applies where you cannot get the 8 feet depth.

IMO, if you had a long enough rod, you could drive it at any angle you want as long as it ends up 8 feet deep.

That is one way to interpret what is said there. With that interpretation one will need longer then an 8 foot rod if it is driven at any angle besides 90 degrees from surface plane.

 

[petersonra]

That is one way to interpret what is said there. With that interpretation one will need longer then an 8 foot rod if it is driven at any angle besides 90 degrees from surface plane.

There is no maximum length of ground rod in the code.

What other possible interpretation is there of what it actually says?

 

[kwired]

There is no maximum length of ground rod in the code.

What other possible interpretation is there of what it actually says?

If it is an 8 foot rod but driven at an angle, the bottom end is going to be less then 8 foot deep when the top end is flush with the surface - or did they change things since I was in geometry class?

I don't think that it is the intent of NEC to mean this, but as is written I can see it being interpreted that way.

 

[petersonra]

If it is an 8 foot rod but driven at an angle, the bottom end is going to be less then 8 foot deep when the top end is flush with the surface - or did they change things since I was in geometry class?

I don't think that it is the intent of NEC to mean this, but as is written I can see it being interpreted that way.

There is no requirement the rod be eight feet long. That is the minimum allowed to be in contact with the soil.

 

[kwired]

There is no requirement the rod be eight feet long. That is the minimum allowed to be in contact with the soil.

correct it says that but then is followed immediately with saying it must be driven at least 8 feet deep. Any angle other then perpendicular should need to use more then 8 ft rod to obtain an 8 foot driven depth if taken literally as printed.

 

[dielectricunion]

I just worked on a service upgrade and saw the POCO pull and replace a power pole for the first time.

They bent the rod and laid it in the hole, sent the wood pole down right on top of it.

I asked why they did it this way and guy kind of smirked as in saying "it's easier". But he said since the 8' will only hit 2' of undisturbed soil, that it was kind of irrelevant which way the rod laid.

 

[kwired]

I just worked on a service upgrade and saw the POCO pull and replace a power pole for the first time.

They bent the rod and laid it in the hole, sent the wood pole down right on top of it.

I asked why they did it this way and guy kind of smirked as in saying "it's easier". But he said since the 8' will only hit 2' of undisturbed soil, that it was kind of irrelevant which way the rod laid.

Couple other good reasons for doing that - if rod is located next to the pole, the pole puts a hole in the "sphere of influence" and having the rod buried deep like that keeps it/GEC to it, from being hit by excavation equipment when someone down the road is trenching a line to the pole.

 

[GoldDigger]

correct it says that but then is followed immediately with saying it must be driven at least 8 feet deep. Any angle other then perpendicular should need to use more then 8 ft rod to obtain an 8 foot driven depth if taken literally as printed.

You could either lengthen the rod by a few inches or just drive the end a few inches below the surface and use a ground clamp rated for direct burial.

 

[kwired]

You could either lengthen the rod by a few inches or just drive the end a few inches below the surface and use a ground clamp rated for direct burial.

If you lengthen the rod it will no longer be same thickness and will bring up other code or listing issues

unless it is of a design where more rod sections are intended to be added, but those add on lengths typically are in more then just a few inch sections.

 

[iwire]

If you lengthen the rod it will no longer be same thickness and will bring up other code or listing issues

unless it is of a design where more rod sections are intended to be added, but those add on lengths typically are in more then just a few inch sections.

10' rods are stock items in my area.

 

[kwired]

10' rods are stock items in my area.

They probably are here as well, but that is a longer rod, not a "lengthened" 8 foot rod

 

[petersonra]

10' rods are stock items in my area.

given how many rods I see with the top end above ground, I am guessing either people are violating the 8' deep rule on a routine basis or are using longer than 8' rods.

 

[kwired]

given how many rods I see with the top end above ground, I am guessing either people are violating the 8' deep rule on a routine basis or are using longer than 8' rods.

My guess is nobody is buying 10 foot rods unless they have good reason to. Those that like to leave just a few inches above grade to be able to see the connection to the rod - I think have good intentions as far as you can see the connection. But unless it is frequently checked by someone that knows what they are looking at, has much better chance of being in an open condition then a buried connection does.--JMO.

 

[iwire]

My guess is nobody is buying 10 foot rods unless they have good reason to.

In my area it is the power company that specs 3/4" x 10' rods when building transformer pads.

We would not buy them if we had a choice. :happyno: