Which one is correct in compliance with code

Status
Not open for further replies.

hhsting

Senior Member
Please see attached sketch. It shows underground water pipe grounding electrode (UWPGE), ground rods and two service discos grounding electrode tapped from each going to common grounding electrode in sketch labeled #1 and #2

I am trying to comply with 250.64(D)(1) and the supplemental electrode req when UWPGE is the only electrode at site however I am not sure where to connect or which one is correct.

#1 in sketch show gnd rods and common grounding electrode conductor tie to UWPGE and #2 in sketch show gnd rods tie to common grounding electrode conductor

Which one is compliance with NEC 2017 section 250?

3b5418ad43b938af6938661817f77eeb.jpg
 

suemarkp

Senior Member
Location
Kent, WA
Occupation
Retired Engineer
I'd be wondering about other things -- which one is the true GEC (which can't be spliced)? What size is the common electrode conductor, and is it sized correctly based on the sum or size of the Service Conductors?

Ideally, panel 1 would be the largest GEC so it is run unspliced to the water pipe. Everything else would tapped off of that common GEC with appropriately sized taps. A copper busbar (sized appropriately) could be allowed as the common electrode instead of one unspliced GEC.
 

hhsting

Senior Member
I'd be wondering about other things -- which one is the true GEC (which can't be spliced)? What size is the common electrode conductor, and is it sized correctly based on the sum or size of the Service Conductors?

Ideally, panel 1 would be the largest GEC so it is run unspliced to the water pipe. Everything else would tapped off of that common GEC with appropriately sized taps. A copper busbar (sized appropriately) could be allowed as the common electrode instead of one unspliced GEC.

Incoming to both service disconnects is 1 set of 500kcmil copper. The common grounding electrode conductor is 2/0 awg copper.

The grounding electrode conductor tap from each service disco to the common grounding electrode is 1/0 awg cu.

I still dont follow other things you are saying??? Given above info what do you think?
 

suemarkp

Senior Member
Location
Kent, WA
Occupation
Retired Engineer
Does the 2/0 common ground go to the water pipe unspliced? If so, this should be compliant.

If I was doing this, I'd just run the 2/0 into one of the two service panels to save the cost of a split bolt and eliminate a splice. Not much cost difference between 1/0 and 2/0. But you are permitted to run a GEC tap to each disconnect.
 

hhsting

Senior Member
Does the 2/0 common ground go to the water pipe unspliced? If so, this should be compliant.

If I was doing this, I'd just run the 2/0 into one of the two service panels to save the cost of a split bolt and eliminate a splice. Not much cost difference between 1/0 and 2/0. But you are permitted to run a GEC tap to each disconnect.

The tap GEC from service disco has to be connected to common grounding electrode right.

Aside from bus there are ways mentioned in nec 2017 section 250.64(D)(1) including exothermic wield for this connection. How is that not code compliant?
 

suemarkp

Senior Member
Location
Kent, WA
Occupation
Retired Engineer
I didnt say it wasnt. You can spend the money for a weld kit too, or just not cut things in the first place. What i was getting at with the unspliced comment is that the conductor to the water pipe needs to be 2/0 and not smaller.

Im not sure how derailed you need to get as a plan reviewer. If every little detail must be spelled out on the plans, then i dont kbow why we train electricians. Conversely, someone could leave a lot of details off the plans hoping the electrician knows the rules and finds the best and cheapest way to do things.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
99% of the jobs I've seen, the exact details end up being a field decision based by the electrician based on what has in his truck :)
"Detailed plans, we don't need no stinkin' plans" :)
 
99% of the jobs I've seen, the exact details end up being a field decision based by the electrician based on what has in his truck :)
"Detailed plans, we don't need no stinkin' plans" :)
Yeah, having been an electrician for 20 years, if I became a plan reviewer.......There are a number of things where I know there are several ways to do it and the exact method depends on the conditions in the field, the conditions of whats in the truck, and the mood of the electrician. For these things I would just write "XYZ to be verified in the field". Sting needs to stop trying to approve every little detail.
 
Status
Not open for further replies.
Top