250.104(D)

[augie47]

A clarification please.
The SDS grounding electrode is required to use the same GES as the structure (250.30) and 250.104 requires bonding the SDS to the structural steel and water.
Do the exceptions to 250.104(D) mean that if the water and steel frame are connected to the service as part of the service GES that there is no need to bond the steel and water in the area of the SDS.
For example, IF I used the exception to 250.121 and used the EGC from my service as my SDS Grounding Electrode Conductor would I still need to bond steel and water in the area of the SDS even if they were part of the structure grounding electrode system ?

 

[jaggedben]

...
Do the exceptions to 250.104(D) mean that if the water and steel frame are connected to the service as part of the service GES that there is no need to bond the steel and water in the area of the SDS[?]
...

The way I read it...
If both water and steel are used as electrodes, then the answer is 'yes, there is no need'.
If only one of the two is used as an electrode, then the two must still be bonded together 'in the area served by the SDS' under exception 2 for either (C)(1) or (2).

The way it comes out:
If it's used as an SDS electrode, you don't have to bond it again to the SDS.
If it's not used as an SDS electrode, then it must be bonded to either (a) the SDS directly, or (b) something 'in the area' that's used as an SDS electrode.

 

[wwhitney]

My take:

Each SDS has an area served (undefined extent, so up to the installer/AHJ to delineate). Within the area served, exposed structural metal and water piping systems must be bonded to the SDS grounded conductor. This can be done either by a bonding jumper, or by the SDS's GEC.

So in the example in the OP, where the primary side EGC also serves as GEC, as long as that GEC is bonded to the same metal water piping system and the same structural steel as those within the area served by the SDS, that suffices for compliance with 250.104(D).

Cheers, Wayne

 

[jaggedben]

My take:

Each SDS has an area served (undefined extent, so up to the installer/AHJ to delineate). Within the area served, exposed structural metal and water piping systems must be bonded to the SDS grounded conductor. This can be done either by a bonding jumper, or by the SDS's GEC.

So in the example in the OP, where the primary side EGC also serves as GEC, as long as that GEC is bonded to the same metal water piping system and the same structural steel as those within the area served by the SDS, that suffices for compliance with 250.104(D).

Cheers, Wayne

There's some nuances. The GEC connection to an electrode can be 'out of the area'. But a connection to a non-electrode (whether GEC or bonding jumper) must be 'in the area.'

Also strictly, I don't see where it says the GEC can be used as a bonding jumper to a non-electrode. Although I also don't know where it says a conductor can't be both.

 

[wwhitney]

But a connection to a non-electrode (whether GEC or bonding jumper) must be 'in the area.'

I agree that the bonding jumper to a metal water piping system under 250.104(D)(1), when neither of the exceptions apply, is required to be "to the nearest available point" of the metal water piping system. Which would make it "in the area."

But 250.104(D)(2) has no such requirement for the exposed structural metal.

Also, in exception 2 to 250.140(D)(1), the phrase "is bonded to the metal water piping in the area" I do not read to require the bond to be in the area, just that the bond is to the metal water piping that exists in the area. All of the "in the area" terminology in 250.104(D)(1) I take to cover the case of more than one metal water piping system existing in the building.

Cheers, Wayne

 

[jaggedben]

...

Also, in exception 2 to 250.140(D)(1), the phrase "is bonded to the metal water piping in the area" I do not read to require the bond to be in the area, just that the bond is to the metal water piping that exists in the area. All of the "in the area" terminology in 250.104(D)(1) I take to cover the case of more than one metal water piping system existing in the building.

I read it the other way. Two questions:

Do you think that in English 'bonded to the thing in the area' unambiguously means only one of the following?

- bonded (to the thing) in the area
- bonded to (the thing in the area)

2nd, if you think there's a convention, do you think the CMP follows that convention on this?

 

[wwhitney]

I read it the other way.

I figured and that reading is reasonable in isolation. But every other use of the phrase "in the area" in 250.140(D) is about the location of the metal water piping or the exposed structural metal. So to me the overall context is clear that the use in Exception 2 to 250.140(D)(1) is similarly about the location of the metal water piping, not about the location of the bond.

Do you think that in English 'bonded to the thing in the area' unambiguously means only one of the following?

- bonded (to the thing) in the area
- bonded to (the thing in the area)

Not 100% unambiguously, but absent other information, the latter is the standard meaning because (a) the phrase "in the area" would generally bind more tightly to the closer phrase and (b) the first interpretation is unambiguously conveyed by "bonded in the area to the thing".

As to the 2nd question, the CMPs don't show much evidence of such careful wordsmithing. : - )

Cheers, Wayne