GROUND CONDUCTOR TO WATERPIPE

[imkrazy49@hotmail.com]

I'M A LITTLE CONFUSED BETWEEN TABLES 250.66 & TABLE 250.122 - WHICH BARE COPPER SIZE DO YOU RUN FOR A 200A RESIDENTIAL SERVICE - I'VE ALWAYS RUN #4CU BUT WAS TOLD LATELY YOU CAN USE #6CU WHAT IS DIFFERENCE BETWEEN THESE TWO TABLES

 

[don_resqcapt19]

Re: GROUND CONDUCTOR TO WATERPIPE

Look at the table titles.

Table 250.66 Grounding Electrode Conductor for Alternating-Current Systems

Table 250.122 Minimum Size Equipment Grounding Conductors for Grounding Raceway and Equipment

What conductor are you asking about?
Actually in your case it doesn't matter as you are required to use Table 250.66 for both the water pipe grounding electrode conductor and the water pipe bonding conductor. See 250.104(A).
Don

[ May 05, 2003, 10:48 AM: Message edited by: don_resqcapt19 ]

 

[physis]

Re: GROUND CONDUCTOR TO WATERPIPE

I'm told you'ld have to use 4 AWG but I also see in 250.66 (A) it says that the grounding electrode conductor doesn't have to be larger than 6AWG copper.

But I'm a rookie at reading directly from the NEC, I may be missing something. If I'm reading it wrong maybe Don can straighten me out.

[ May 05, 2003, 12:19 PM: Message edited by: physis ]

 

[bennie]

Re: GROUND CONDUCTOR TO WATERPIPE

A made electrode is one installed by the electrician. The water pipe is installed by the plumber. We want more current on their systems than ours. This is why the larger conductor

 

[don_resqcapt19]

Re: GROUND CONDUCTOR TO WATERPIPE

physis,
You have to read all of 250.66(A) and the sections that it refers you to. 250.66(A) is refering to "made electrodes", as Bennie has pointed out. Made electrodes of the rod or plate type, see 250.52(A)(5) and (6), only require a #6 grounding electrode conductor. The metal water pipe connection is always sized by Table 250.66. The word "pipe" in 250.66(A) is a source of confusion for many.
don

 

[physis]

Re: GROUND CONDUCTOR TO WATERPIPE

I see, no wonder.

looking at 250.66(A) and 250.52(a)(5) I don't see anything that would exclude the waterpipe, in fact, it appears to define a water pipe as a grounding electrode that qualifies under 250.66(A) given some requirements.

Thanks Don and Bennie

[ May 06, 2003, 05:55 AM: Message edited by: physis ]

 

[stevet]

Re: GROUND CONDUCTOR TO WATERPIPE

250.66 refers to the largest ungrounded service entrance conductor. They allow you 2/0 on a single family dwelling. So, #4 for 2/0 copper

 

[tom baker]

Re: GROUND CONDUCTOR TO WATERPIPE

Does your water pipe actually qualify as a grounding electrode with ten feet in contact with the soil? If not you make a bonding connection per 250.104, still size per 250.122, but the location only has to be accessible, not within 5 ft of the entrance to the building,