grounding Table 250.66 question

[christlike]

[FONT=wf_segoe-ui_normal]Hey mike can u shed some light on Table 250.66? Does the table refer to residential, commercial, and industrial? Does it refer to the primary grounding: metal underground water pipe, or does this table refer to the supplemental electrode system? Even though I know full well how to interpret the table in conjuction with table 310.15 B 7 dwelling service conductor sizes, I have a dillema I ran #6 copper wire from the hot, cold, and gas back to the 200 amp dwelling service panel is this legal according to 250.66 (A) "grounding electrode conductor shall not be required to be larger than 6 awg copper ". Does 250.66(A) connections to Rod, pipe, or plates electrodes refer to the supplemental grounding? So not to confuse any more, my question is basically this: for a 200 amp dwelling service do I go with a size 4 copper grounding electrode (according to table)conductor for the 2 driven ground rods or is it for the cold water meter/ hot water tank closet hot, cold, and gas? And where am I allowed to use the size 6 copper wire then according to the exceptions of 250.66 (A) [/FONT]

 

[don_resqcapt19]

250.66(A) does not refer to pipe as pipe in a water piping system. It only refers to pipe driven in the ground to be used as a grounding electrode.

(5) Rod and Pipe Electrodes. Rod and pipe electrodes shall not be less than 2.44 m (8 ft) i n length and shall consist of the following materials.
(a) Grounding electrodes of pipe or conduit shall not be smaller than metric designator 21 (trade size 3⁄4) and, where
of steel, shall have the outer surface galvanized or otherwise metal-coated for corrosion protection.
(b) Rod-type grounding electrodes of stainless steel and copper or zinc coated steel shall be at least 15.87 mm (5⁄8 in.)
in diameter, unless listed.

 

[roger]

[FONT=wf_segoe-ui_normal] So not to confuse any more, my question is basically this: for a 200 amp dwelling service do I go with a size 4 copper grounding electrode (according to table)conductor for the 2 driven ground rods[/FONT]

[FONT=wf_segoe-ui_normal]250.66(A) is your answer for rods

or is it for the cold water meter/

If the water entrance meets the requirement of 250.52(A)(1) you would size the GEC per Table 250.66

hot water tank closet hot, cold, and gas?[

These items would more likely (not necessarily) fall under bonding per 250.104

And where am I allowed to use the size 6 copper wire then according to the exceptions of 250.66 (A)

[/FONT]There are no exceptions to 250.66(A), a number 6 is all that is required for connection to rods.

Roger

 

[christlike]

250.66

250.66

Thanks Don that brought alot of clarification, so supplemental ground refers to your ground rods which doesnt have to be any bigger than size 6 AWG even on a 200 amp service. By the ways your cold, hot, and gas (in the boiler closet)just have to be bonded with a short jumper wire, and the water meter jumpered and going back to the panel. Inspector said it creates a false ground if you have one homerun from water meter, and then an additional homerun from hot water tank closet.

 

[Smart $]

Thanks Don that brought alot of clarification, so supplemental ground refers to your ground rods which doesnt have to be any bigger than size 6 AWG even on a 200 amp service. By the ways your cold, hot, and gas (in the boiler closet)just have to be bonded with a short jumper wire, and the water meter jumpered and going back to the panel. Inspector said it creates a false ground if you have one homerun from water meter, and then an additional homerun from hot water tank closet.

That's basically right.

There is no requirement to run a bonding jumper from the panel to the hot water pipe. A jumper from the cold to the hot is all that is needed and even that is just a fail safe just in case there's no solid metal connection in the plumbing such as through a faucet with plastic supply tubing rather than metal. The jumper around the water meter covers the cold water pipe being bonded.

Unless you have CSST that requires bonding, the NEC basically says bonding gas pipe is covered by the EGC of the circuit likely to energize the piping.
[Listed?] gas equipment powered by the circuit typically assures the piping port is EGC bonded. If not, you bond around with an EBJ from the circuit EGC... and all's well. If the AHJ makes you bond the gas line, it is really because they don't want to inspect the gas equipment for proper bonding.

 

[Smart $]

Thanks Don that brought alot of clarification, so supplemental ground refers to your ground rods which doesnt have to be any bigger than size 6 AWG even on a 200 amp service. ...

GEC to rods can be #6 on any size service, whether supplemental or not... as long as it only connects one or more rod/pipe/plate. If it connects rod/pipe/plate AND other non-rod/pipe/plate electrodes, it has to be sized per the Table.

 

[don_resqcapt19]

... Inspector said it creates a false ground if you have one homerun from water meter, and then an additional homerun from hot water tank closet.

I have no idea what the inspector is talking about. There is no code or technical issue with running multiple bonding conductors to the water pipes.

 

[Smart $]

... Inspector said it creates a false ground if you have one homerun from water meter, and then an additional homerun from hot water tank closet.

I have no idea what the inspector is talking about. There is no code or technical issue with running multiple bonding conductors to the water pipes.

The inspector may be trying to point out that running a EBJ to the hot water closet may incite one to believe bonding the water pipe electrode is covered. Perhaps???

As noted in my earlier, an EBJ from panel to hot water closet is not specifically required by Code (as I'm sure you are aware). OP'er is from Ohio and I know several NE Ohio local jurisdictions require hot water and gas pipe to be bonded. Out of ignorance, or tradition, I don't know. It's not a State amendment to Code AFAIK and technically State is the AHJ, while local jurisdictions are just the enforcers.

 

[christlike]

The inspector may be trying to point out that running a EBJ to the hot water closet may incite one to believe bonding the water pipe electrode is covered. Perhaps???

As noted in my earlier, an EBJ from panel to hot water closet is not specifically required by Code (as I'm sure you are aware). OP'er is from Ohio and I know several NE Ohio local jurisdictions require hot water and gas pipe to be bonded. Out of ignorance, or tradition, I don't know. It's not a State amendment to Code AFAIK and technically State is the AHJ, while local jurisdictions are just the enforcers. In regards to mentioning that the supplemental could also be bonded to something other than rod, pipe, or plate electrodes, would'nt that be redundant, they already get bonded at the service panel. Isnt that why the code considers this Supplemental, and it follows the supplemental EGC SIZE #6 AWG no matter what the service size?

 

[christlike]

gas line

gas line

I yet havent come across a house that uses CSST for gas lines, but now know that they require proper bonding do to the dangers that lightning strikes impose on CSST

 

[Smart $]

In regards to mentioning that the supplemental could also be bonded to something other than rod, pipe, or plate electrodes, would'nt that be redundant, they already get bonded at the service panel. Isnt that why the code considers this Supplemental, and it follows the supplemental EGC SIZE #6 AWG no matter what the service size?

This statement leads me to believe you do not understand Code use of the term supplemental with regard to grounding electrode conductors.

Refer to 250.53. A supplemental grounding electrode is required in two scenarios: 1) you have a single rod/pipe/plate electrode, or 2) you have a water pipe electrode... and no other electrode for both. For either scenario, the supplemental electrode can be a type specified in 250.52(A)(2) through (A)(8) ... which essentially says any type electrode other than a second metal water pipe electrode (don't ask me why as I have no idea why... it should be permitted if there is a second that qualifies and separated by more than 6').

What this amounts to is if you have a metal water pipe electrode or a rod/pipe/plate electrode, there will always be second electrode. In the instance where you have a water pipe electrode and a rod/pipe/plate electrode, there will be always be a third electrode... unless the exception to 250.53(A)(2) is met, and most prefer to just go with the third as another rod.

While there is some interconnection requirements in 250.53, it amounts to once 250.53 is satisfied, qualifying electrodes are qualifying electrodes and the supplemental issues no longer matter if you comply with 250.66.

The problem most have with the lettered subsections of 250.66 is the "sole connection" part. It's really quite simple. If the GEC [portion] connects an electrode other than the type* in the title to the system, then it has to be sized per the Table. Otherwise it can be sized per the subsection.

*Under subsection (A), multiple rods/pipes/plates are permitted to be connected with a #6. Subsections (B) and (C) only apply to single electrodes.

 

[kwired]

I yet havent come across a house that uses CSST for gas lines, but now know that they require proper bonding do to the dangers that lightning strikes impose on CSST

But the rules that apply to bonding CSST are found in product instructions and is not part of NEC. Many of us believe bonding that piping is the pipe installers problem, and is one reason we are supposed to install an intersystem bonding termination so they will have a place to connect it to the electrical system.