Shed Sub panel 2 rods or 1

[Jerseydaze]

50 amp sub panel to a shed residential do I need 1 grod or 2 ?

 

[iwire]

50 amp sub panel to a shed residential do I need 1 grod or 2 ?

Unless you can prove you have under 25 ohms resistance with one rod you will need two.

 

[goldstar]

I'm making an assumption that you have a new service and that service has 2 rods connected to the main breaker panel along with a water main ground. You'll be running 6/3 w/ground or equivalent to the shed so, IMHO you'll only need one rod to re-establish the ground at the shed. However, I would check with the EI or the State to make sure. It's only a phone call.:thumbsup:

 

[iwire]

I'm making an assumption that you have a new service and that service has 2 rods connected to the main breaker panel along with a water main ground. You'll be running 6/3 w/ground or equivalent to the shed so, IMHO you'll only need one rod to re-establish the ground at the shed. However, I would check with the EI or the State to make sure. It's only a phone call.:thumbsup:

How do you get around the code requirements?

250.32 Buildings or Structures Supplied by a Feeder(s)
or Branch Circuit(s).
(A) Grounding Electrode. Building(s) or structure(s) supplied
by feeder(s) or branch circuit(s) shall have a grounding
electrode or grounding electrode system installed in
accordance with Part III of Article 250.

250.53 Grounding Electrode System Installation.

(A) Rod, Pipe, and Plate Electrodes. Rod, pipe, and plate
electrodes shall meet the requirements of 250.53(A)(1)
through (A)(3).

(2) Supplemental Electrode Required. A single rod, pipe,
or plate electrode shall be supplemented by an additional
electrode of a type specified in 250.52(A)(2) through
(A)(8). The supplemental electrode shall be permitted to be
bonded to one of the following:

(1) Rod, pipe, or plate electrode

(2) Grounding electrode conductor

(3) Grounded service-entrance conductor

(4) Nonflexible grounded service raceway

(5) Any grounded service enclosure

Exception: If a single rod, pipe, or plate grounding electrode
has a resistance to earth of 25 ohms or less, the
supplemental electrode shall not be required.

The AHJ might ignore the requirements but the requirements are there for a supplemental electrode unless you use the exception.

(2011 NEC sections above)

 

[infinity]

I'm making an assumption that you have a new service and that service has 2 rods connected to the main breaker panel along with a water main ground. You'll be running 6/3 w/ground or equivalent to the shed so, IMHO you'll only need one rod to re-establish the ground at the shed. However, I would check with the EI or the State to make sure. It's only a phone call.:thumbsup:

The separate structure requires it's own grounding electrode system for the sub-panel. As Bob stated that can only be one rod if you can prove the 25 ohms or less.

 

[Ponchik]

Unless you can use the exception as stated by Bob or it is a local amendment that 2nd grounding electrode is not required. Locally we do not need the 2nd electrode.

Call your AHJ and ask.

 

[jaggedben]

Holy !@#$. :slaphead:

I just realized that a major AHJ I've been working in for a long time is over-interpreting the code. They require the water and 2 ground rods, on the theory that if you can't prove that the first ground rod is less than 25ohms then you need a second one. Whereas really the first rod is already the supplemental required by the code. :rant:

I certainly feel like I should have known this.
End rant.

 

[roger]

Holy !@#$. :slaphead:

I just realized that a major AHJ I've been working in for a long time is over-interpreting the code. They require the water and 2 ground rods, on the theory that if you can't prove that the first ground rod is less than 25ohms then you need a second one. Whereas really the first rod is already the supplemental required by the code. :rant:

I certainly feel like I should have known this.
End rant.

The AHJ is correct, the single rod would have to be 25 ohms or it would not be considered a supplemental GE, see 250.53(D)(2), the supplemental GE must meet the requirements of 250.53(A)(2) which would mean two rods or bring out a test set

Roger

 

[infinity]

Holy !@#$. :slaphead:

I just realized that a major AHJ I've been working in for a long time is over-interpreting the code. They require the water and 2 ground rods, on the theory that if you can't prove that the first ground rod is less than 25ohms then you need a second one. Whereas really the first rod is already the supplemental required by the code. :rant:

I certainly feel like I should have known this.
End rant.

As Roger stated the AHJ is correct. A single rod is not an electrode if it cannot pass the 25 ohms or less test. Two rods are considered an electrode no testing required.

 

[goldstar]

How do you get around the code requirements?
The AHJ might ignore the requirements but the requirements are there for a supplemental electrode unless you use the exception.
(2011 NEC sections above)

The separate structure requires it's own grounding electrode system for the sub-panel. As Bob stated that can only be one rod if you can prove the 25 ohms or less.

I made the assumption that the main service was new and that it had the appropriate grounding electrode system in place. I also made the assumption that the OP would be running some type of 6/3 cable or equivalent (underground conductors in PVC, overhead quadplex, etc.). So, you already have an equipment grounding wire inside that cable assembly or conduit. Driving one rod would supplement that grounding system. If I've mis-interpreted this then I stand corrected.

 

[iwire]

I made the assumption that the main service was new and that it had the appropriate grounding electrode system in place. I also made the assumption that the OP would be running some type of 6/3 cable or equivalent (underground conductors in PVC, overhead quadplex, etc.). So, you already have an equipment grounding wire inside that cable assembly or conduit. Driving one rod would supplement that grounding system. If I've mis-interpreted this then I stand corrected.

While what you suggests makes sense you cannot use the service grounding electrodes to supplement a single rod at a remote building.

You must use new electrodes.

 

[K8MHZ]

Is the second rod such a big deal it's worth spending time on an Internet forum to figure out a way around using one?

I ask this generically, not aimed specifically at the OP. I have seen several threads posted by people trying to get out of driving a second rod.

To me, they end up spending more time (time is money) trying to get out of pounding a rod than they would have in doing it.

Every EC I have worked for put in two rods and spares the hassle of trying not to.

 

[roger]

Is the second rod such a big deal it's worth spending time on an Internet forum to figure out a way around using one?

I ask this generically, not aimed specifically at the OP. I have seen several threads posted by people trying to get out of driving a second rod.

To me, they end up spending more time (time is money) trying to get out of pounding a rod than they would have in doing it.

Every EC I have worked for put in two rods and spares the hassle of trying not to.

And I agree, drive the second rod and go to the house. Most people use electric hammers anyways.

Roger

 

[kwired]

I made the assumption that the main service was new and that it had the appropriate grounding electrode system in place. I also made the assumption that the OP would be running some type of 6/3 cable or equivalent (underground conductors in PVC, overhead quadplex, etc.). So, you already have an equipment grounding wire inside that cable assembly or conduit. Driving one rod would supplement that grounding system. If I've mis-interpreted this then I stand corrected.

An electrode at the service also supplements the rest of the supply grid, but we still have grounding electrode system requirements at the building with the service, as well as at the separate building supplied by a feeder. That second building needs to follow same rules as the first - if there is building steel, qualifying water pipe, or a concrete encased electrode they must be used, otherwise you have a few choices on "made electrodes" but rules for them don't change just because there is already a grounding electrode system at the structure that supply comes from.

 

[Ponchik]

Is the second rod such a big deal it's worth spending time on an Internet forum to figure out a way around using one?

I ask this generically, not aimed specifically at the OP. I have seen several threads posted by people trying to get out of driving a second rod.

To me, they end up spending more time (time is money) trying to get out of pounding a rod than they would have in doing it.

Every EC I have worked for put in two rods and spares the hassle of trying not to.

I agree if it is single house then OK it may be easier to install the 2nd rod and get done with it. Respectfully, at the same time I disagree. If it is not needed why put one in?

Going with the mentality "just put one in and get done with it" may not make a financial sense if the project is multi tract home project. Or going with the same mentality, one may also say "oh what the hell, just install a 1" EMT, you don't need to do any calcs"

IMO, one should know what the basic requirements are then make an informed decision. As I had mentioned in my earlier post, local AHJ do not require the 2nd ground rod. So, why put one in?

 

[iwire]

As I had mentioned in my earlier post, local AHJ do not require the 2nd ground rod. So, why put one in?

Because the code requires it unless I prove 25 ohms, so every temporary service I do gets 2 rods. One 'redo' for a failed inspection costs more than installing a large number of rods.

 

[kwired]

I agree if it is single house then OK it may be easier to install the 2nd rod and get done with it. Respectfully, at the same time I disagree. If it is not needed why put one in?

Going with the mentality "just put one in and get done with it" may not make a financial sense if the project is multi tract home project. Or going with the same mentality, one may also say "oh what the hell, just install a 1" EMT, you don't need to do any calcs"

IMO, one should know what the basic requirements are then make an informed decision. As I had mentioned in my earlier post, local AHJ do not require the 2nd ground rod. So, why put one in?

If local AHJ don't require 2nd rod then don't put it in if you do not wish to for whatever reason.

If the local AHJ is enforcing NEC as written then latest couple editions do require the second rod unless you prove the first is 25 ohms or less, proving the resistance of the first rod typically will cost more then driving the second rod and is why most people do that.

 

[1964element]

I'm working on a farm rack 400 coming in to two 200 amp discos one feeding a pole barn second to new home.
I have two rods for each disco. I will be running 4 wire quadplex 4/0 to each building will I need driven rods at those locations.



Sent from my E6782 using Tapatalk

 

[Ponchik]

Because the code requires it unless I prove 25 ohms, so every temporary service I do gets 2 rods. One 'redo' for a failed inspection costs more than installing a large number of rods.

If local AHJ don't require 2nd rod then don't put it in if you do not wish to for whatever reason.

If the local AHJ is enforcing NEC as written then latest couple editions do require the second rod unless you prove the first is 25 ohms or less, proving the resistance of the first rod typically will cost more then driving the second rod and is why most people do that.

I am not arguing with the fact that It may be easier just to put one in instead of hassling with the AHJ. All I am saying is know the basics, get yoru information then make a decision. Don't just assume the 2nd rod is a MUST.

Similar to "don't just install a 1" conduit through out the job without doing your research/calculations" or "don't assume there is only 2 NM cablse per hole just because... " That is all I am trying to get across.

Maybe I should have mentioned it earlier that the local AHJ has done extensive testing throughout the city and determined the 2nd rod is not required.

 

[infinity]

I am not arguing with the fact that It may be easier just to put one in instead of hassling with the AHJ. All I am saying is know the basics, get yoru information then make a decision. Don't just assume the 2nd rod is a MUST.

Similar to "don't just install a 1" conduit through out the job without doing your research/calculations" or "don't assume there is only 2 NM cablse per hole just because... " That is all I am trying to get across.

Maybe I should have mentioned it earlier that the local AHJ has done extensive testing throughout the city and determined the 2nd rod is not required.

If the AHJ accepts one rod without testing that's great. The NEC requires two rods or the testing.