grounding

[pablodiaz7]

Can a secondary panel's metallic enclosure, be permitted o be grounded to a grounding electrode?

 

[shepelec]

Can a secondary panel's metallic enclosure, be permitted o be grounded to a grounding electrode?

When you say "secondary panel" are you reffering to a panel fed by a transformer or a sub panel?

 

[Volta]

If you mean fed directly from another panel (with no transformer in between), then yes, the enclosure is allowed to be connected to an Auxiliary Grounding Electrode 250.54. However, it must also be connected to the Grounding Electrode System 250.58. The earth shall not be considered as an effective ground-fault current path 250.4(A)(5).

So you still need to run an EGC with the circuit conductors 250.110, 250.134, 408.40.

 

[Smart $]

If you mean fed directly from another panel (with no transformer in between), then yes...

The answer is yes in any case... just the terms and requirements change

In the case where it is fed from a Separately Derived System (SDS) (e.g. transformer), the panel must also contain one or more of the six permitted System Disconnecting Means and a System Bonding Jumper (SBJ) if system is grounded. The electrode used would be part of the SDS GES [ref: 250.30].

In the case where the panel is fed from a non-SDS transformer or an SDS where the Grounding Electrtode System (GES) and SBJ, it would be treated as you describe for a directly-connected panel.

An auxiliary grounding electrode can neither be connected nor required to be connected to any GES. (No reference, just a matter of deductive reasoning ).

 

[pablodiaz7]

When you say "secondary panel" are you reffering to a panel fed by a transformer or a sub panel?

I'm referring to a panel fed by the service equipment or MDF

 

[Smart $]

...

In the case where the panel is fed from a non-SDS transformer or an SDS where the Grounding Electrtode System (GES) and SBJ are connected at the transformer, it would be treated as you describe for a directly-connected panel.

...

Inserted red text in quote of previous post.

 

[Smart $]

I'm referring to a panel fed by the service equipment or MDF

MDF ??? (which I take to mean Medium Density Fiberboard)

How about MDP, Main Distribution Panel

Question previously answered... but ask if you need more elaboration.

 

[pablodiaz7]

if you mean fed directly from another panel (with no transformer in between), then yes, the enclosure is allowed to be connected to an auxiliary grounding electrode 250.54. However, it must also be connected to the grounding electrode system 250.58. The earth shall not be considered as an effective ground-fault current path 250.4(a)(5).

So you still need to run an egc with the circuit conductors 250.110, 250.134, 408.40.

thanks....very clear

 

[infinity]

An auxiliary grounding electrode can neither be connected nor required to be connected to any GES. (No reference, just a matter of deductive reasoning ).

Can't an auxiliary ground can be connected to just about anything?

 

[Smart $]

Can't an auxiliary ground can be connected to just about anything?

Nope...

According to 250.54, they can only be connected to EGC's.

 

[cschmid]

Can a secondary panel's metallic enclosure, be permitted o be grounded to a grounding electrode?

never mind me...question answered....

 

[Volta]

The answer is yes in any case... just the terms and requirements change

Yup.

An auxiliary grounding electrode can neither be connected nor required to be connected to any GES. (No reference, just a matter of deductive reasoning ).

?

Nope...

According to 250.54, they can only be connected to EGC's.

Hmmm, I don't see that. 250.54 allows them to exist, and permits them to be connected to the EGCs.
It also relieves us of the some of the requirements imposed for electrodes 250.50 (all together now) and bonding jumpers 250.53(C) namely methods [much of 250.64], and 250.70.
It does not restrict us from connecting to the GES directly in that section.

An auxiliary grounding electrode (AGE) present at each -wait a minute-

Man, you're good!

If an AGE is connected to the GES, it becomes a regular or Supplemental Electrode. It then must meet the requirements previously excepted for AGEs. So if you want to connect an AGE to the GES, it must be constructed such that it does not meet the description of 250.52(A)(1) through (7). If we cut an inch off of an eight foot rod, it is no longer subject to 250.50, and we can then connect it to the GES in any manner desired.

Is that where you were going?

 

[Smart $]

...

If an AGE is connected to the GES, it becomes a regular or Supplemental Electrode. It then must meet the requirements previously excepted for AGEs. So if you want to connect an AGE to the GES, it must be constructed such that it does not meet the description of 250.52(A)(1) through (7). If we cut an inch off of an eight foot rod, it is no longer subject to 250.50, and we can then connect it to the GES in any manner desired.

Is that where you were going?

Simply stated, an electrode connected at any point along the GES, including the point where the MBJ/SBJ is connected, is not [solely] an EGC connection, which is what 250.54 states

Any non-required conforming electrode connected to the GES is a Supplemental Electrode. If a non-conforming electrode is connected to the GES, I don't know what it is, for the Code makes no provision for doing so, nor what to call such an electrode... but it is most certainly is not an AGE

 

[cschmid]

Can a secondary panel's metallic enclosure, be permitted to be grounded to a grounding electrode?

ok I was going to not say anything but I do like this topic and this question leaves us with more questions: which then us producing opinions off of assumptions.

I assume he means bonded to the Grounding electrode. I could assume he means a separate grounding electrode conductor to the panel but would you classify that as a bonded enclosure with just a different then normal path. But with olt more conclusive info we are really just guessing, are we not.

 

[infinity]

If an AGE is connected to the GES, it becomes a regular or Supplemental Electrode. It then must meet the requirements previously excepted for AGEs. So if you want to connect an AGE to the GES, it must be constructed such that it does not meet the description of 250.52(A)(1) through (7). If we cut an inch off of an eight foot rod, it is no longer subject to 250.50, and we can then connect it to the GES in any manner desired.

Volta,
Where did you find this information? 250.54 says that it "shall be permitted to be connected to the equipment grounding conductor" which according to Article 90 is a permissive rule. I don't see where this particular section would prohibit an auxiliary electrode from being connected to just about anything including the GES. Am I missing something (other than coffee at this hour) .

250.54 Auxiliary Grounding Electrodes.
One or more grounding electrodes shall be permitted to be connected to the equipment grounding conductors specified in 250.118 and shall not be required to comply with the electrode bonding requirements of 250.50 or 250.53(C) or the resistance requirements of 250.56, but the earth shall not be used as an effective ground-fault current path as specified in 250.4(A)(5) and 250.4(B)(4).

90.5 Mandatory Rules, Permissive Rules, and Explanatory Material.
(A) Mandatory Rules. Mandatory rules of this Code are those that identify actions that are specifically required or prohibited and are characterized by the use of the terms shall or shall not.
(B) Permissive Rules. Permissive rules of this Code are those that identify actions that are allowed but not required, are normally used to describe options or alternative methods, and are characterized by the use of the terms shall be permitted or shall not be required.

 

[Smart $]

... I don't see where this particular section would prohibit an auxiliary electrode from being connected to just about anything including the GES. Am I missing something (other than coffee at this hour) .

250.54 is the only "definition" provided for Auxiliary Grounding Electrodes (AGE, in singular form). If a connected electrode does not fall within the parameters therein, it is not an AGE... which would mean any grounding electrode connected to the GES is not an AGE.

 

[Volta]

Volta,
Where did you find this information? 250.54 says that it "shall be permitted to be connected to the equipment grounding conductor" which according to Article 90 is a permissive rule. I don't see where this particular section would prohibit an auxiliary electrode from being connected to just about anything including the GES. Am I missing something (other than coffee at this hour) .

I started that post fully on the side of AGE allowed to be connected to the GES. I was trying to figure out how to show that, as Smart $ was taking the stance of not allowed.

Hmmm, I don't see that. 250.54 allows them to exist, and permits them to be connected to the EGCs.
...It does not restrict us from connecting to the GES directly in that section.

While working through that, I realized that semantics were likely needed to allow the AGE on the GES. If we drew it out, without calling the Auxiliary Electrode such (let's stay with a ground rod for our example) we might find a driven rod, 8' of which in contact with the soil, and a #10 awg wire connecting it to the GES. Previously, I would have thought that ok per 250.54. But looking at it objectively, it is an electrode availabe on premises, that conforms to 250.52(A)(4). If it is that, doesn't 250.50 require us to bond them "together to form the grounding electrode system"?

The only logical way I can see to justify not doing that is to interpret 250.54 as only permitting a rod that is present at the building or structure to not comply with 250.50, .53(C), or .56 when connected to a permitted EGC instead.