grounding a service without a water line

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See 250.50. You are to use all electrodes present, and if none are present, add one as directed by that section. Take note of 250.56 as well.
 
LarryHatcher said:
if you do not have a cold water ground how is the service to be grounded?
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I recently did a building with all-plastic plumbing, except for the sprinkler supply, which we are specifically not permitted to bond to.

The only grounding electrodes were the two driven rods. I did, however, make the service neutrals larger than calcs required.
 
See Article 250.52 (A) (2), (3), (4)

also ufer grounding, ground rings, rod and pipe electrodes, plate electrodes, other underground metallic objects of immense size (tanks, piping, well casings etc)
 
LarryFine said:
I recently did a building with all-plastic plumbing, except for the sprinkler supply, which we are specifically not permitted to bond to.

The only grounding electrodes were the two driven rods. I did, however, make the service neutrals larger than calcs required.
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Why wouldn't this building have a CEE or was it existing?
 
iwire said:
What does one have to do with the other?
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I understand the question, and I'll give you my answer, right or wrong. I didn't do it for profit, but more as what I call the 'performance' of the electrical system. This is a mixed-use service, a single drop supplied from a high-leg open Delta. The services supplied are:

(1) a pair of 200a residential ML panels, which share a riser of two cu 250Kcmil's and a cu 1/0 neutral leading to a twin meter base and two 200a disco's (all 1ph) followed by 4/0al SER, and

(2) a 200a MB panel (1ph) servicing the commercial space (and common area) using two 3/0cu's and a 1/0cu neutral. A tap box under the 3ph meter supplies a separate 30a 3ph AC unit via a 100a panel fed with three #4cu's.

My calcs showed that I could have used a #4cu neutral for the residential riser, and a #6cu for the commercial space's neutral. I chose to go with 1/0cu for both neutrals simply to improve the impedance of the neutral pathway.

Since driven grounds are among the weakest types of electrodes, and there is no metallic water piping, which is probably the best electrode in an all-metal water system (neighborhood, not just one building), I just felt enlarging the service neutrals was beneficial.

It certainly did no harm, and the difference was under $35.


infinity said:
Why wouldn't this building have a CEE or was it existing?
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Very much existing. All brick, probably 100 years old, completely gutted.
 
Larry,
Since driven grounds are among the weakest types of electrodes, and there is no metallic water piping, which is probably the best electrode in an all-metal water system (neighborhood, not just one building), I just felt enlarging the service neutrals was beneficial.
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I still don't understand. I don't see any connection between the size of the grounded conductor and the type of grounding electrodes.
Don
 
don_resqcapt19 said:
I still don't understand. I don't see any connection between the size of the grounded conductor and the type of grounding electrodes.
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I know, I know. There is no direct connection between the two. The neutral need not be larger than the otherwise-required (i.e., other than the driven rods' #6) GEC if the calcs don't require it to be. This was a performance-based choice, not a compliance-based one.

It was really just a whim on my part that this be one of those times that I go a bit beyond the minimum requirements. As the only conductor working to keep the premises equipment anywhere near zero volts to earth, I decided to provide a little less impedance in the neutral. Silly me.
 
LarryFine said:
This was a performance-based choice, not a compliance-based one.
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Larry I certainly respect a guy who wants to go beyond the minimum required. :cool:

That said I really don't see how the larger neutral increased the performance of the system.
 
Without looking too closely at the numbers (or at all, this morning ;) ), I wouldn't be thinking about the earth when upsizing the neutral - I'd be doing it for a better short circuit and ground fault clearing path, to make breakers kick sooner.
 
I agree George, and possibly for additive harmonics.

Roger
 
Here in the City of Tampa we suggest 2 ground rods and a concrete encased electrode for new construction. Service changes on existing houses, only 2 ground rods are required (I disagree I feel additional are needed, given the soil conditions in Florida). We can and have requested Engineer certified 3rd party "Meg" test reports on GES's suspect less than the required 25 ohms.
 
Neal, welcome to the forum. :)

COTInspector said:
Service changes on existing houses, only 2 ground rods are required (I disagree I feel additional are needed, given the soil conditions in Florida).
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Why do you feel additional rods are needed?

We can and have requested Engineer certified 3rd party "Meg" test reports on GES's suspect less than the required 25 ohms.
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What are the typical results of these tests?

Here in the City of Tampa we suggest 2 ground rods and a concrete encased electrode for new construction.
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Suggest or require? In writing?
 
grounding service without a water line

grounding service without a water line

don_resqcapt19 said:
Larry,

I still don't understand. I don't see any connection between the size of the grounded conductor and the type of grounding electrodes.
Don
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I don't either.
 
LarryHatcher said:
if you do not have a cold water ground how is the service to be grounded?
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A "U-fer" is the best if you?re doing new construction (250-52(3)) because it has the lowest resistance and is least likely to be tampered or altered later.

250-50 also tells us to use one or more of the electrodes specified in (A)(4) through (A)(7) if no electrodes exist which is your case. The ground rod, in (A)(5), is most common but again it is not as efficient as a U-fer for resistance.

What is the purpose for the ground anyway?
 
georgestolz said:
. . . I wouldn't be thinking about the earth when upsizing the neutral - I'd be doing it for a better short circuit and ground fault clearing path, to make breakers kick sooner.
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That's what I had in mind. Not keeping the service neutral at ground, but closer to the utility neutral.
 
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