EGC...
EGC...
Your question should not be about the GEC. Please read posts #3 and @#18 carefully....
EGC...
Your question should not be about the GEC. Please read posts #3 and @#18 carefully....
Common practice for well casings?
- Thread starter TimWA
- Start date
- Status
- Location
- Massachusetts
Dennis and I were discussing using the casing as an electrode.
I realize that, but at a hundred feet away for a well motor system from a main disconnect, that becomes irrelevant in the case electrode-to- soil impedance effectivity.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I am confused. I thought we were talking about the fact that it probably would not be effective as an electrode at that distance. :?
Hi Dennis,
PAX. If Bob's dialog was in reference to a casing not being effective as an electrode I do agree and must have missed it. I guess I was too focused on answering the OP's initial question with the reason why requiring an EGC bonding is imperative for well metal casing equipment safety.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
Metal well casings are still common in my area.
Hi George,
Interesting....for deep submersible water? Is there a reason for using the metal? For agri? Mining including gas?
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Are they metal for the full depth of well?
There are old metal wells here also.
New ones for at least 25-30 years are usually non metallic. The last few feet, and/or 'pitless adapters' will usually be steel to stand up to physical abuse above grade. I live in "irrigation country" and there are a lot of wells from 4 inch to 12 inch casings everywhere.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
For residential-use submersible pumps. No idea, no idea, no idea.
Not typically, but I know of one well driller that does. I think mine goes down 20 or 30' to prevent surface water from entering the well, I think.
I'd post a picture of mine, but it's under snow at the moment.
Why would a ground rod be required to be connected with a #6 , but a well casing (which I believe would be a far superior ground rod ) only be required to be connected with a # 12 if the pump had a 20 a OCPD?
I could understand anything likely to become energized to have a EGC appropriate to the size of the OCPD, but I don't think a well casing is an ordinary " likely to become energized" ... I think it is more of a grounding electrode.
I could understand anything likely to become energized to have a EGC appropriate to the size of the OCPD, but I don't think a well casing is an ordinary " likely to become energized" ... I think it is more of a grounding electrode.
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kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
For residential-use submersible pumps. No idea, no idea, no idea.
Not typically, but I know of one well driller that does. I think mine goes down 20 or 30' to prevent surface water from entering the well, I think.
I'd post a picture of mine, but it's under snow at the moment.
The only way to keep surface water out is to slope grade away from the well. Metal or plastic, unless there is a failure water only enters in the locations where casing intentionally has holes or "screen" to allow water in. Surface water if not drained away from well will percolate down into the supply that feeds the well, but has nothing to do with whether or not a metallic or non metallic casing is used.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
In one case you are using the ground rod as an electrode in the situation of the well case you are just bonding the casing and not using it as an electrode. In the event that it is used as an electrode then I believe you would need to follow 250.66.
For residential-use submersible pumps. No idea, no idea, no idea.
Not typically, but I know of one well driller that does. I think mine goes down 20 or 30' to prevent surface water from entering the well, I think.
I'd post a picture of mine, but it's under snow at the moment.
George,
Thanks for the input. Until the advent of PVC for well casing, thousands of existing metal wells throughout the US were dominant. In the many years of wiring well systems (as far back as 1973), I have had the experience of rewiring old steel or CI wells for safety bonding. All new wells I have set pumps in are PVC, and as a main point in this discussion, does not exempt the well equipment or metal casing from not having bonding with an EGC.
A good reference source is the National Driller and the NGWA.org (National Ground Water Association) for various drilling conditions that dictate steel or PVC.
From an economical and practical view, Google up 'well drilling casing' and click on Steel or PVC for a good pdf explanation.
Good point about pitless adapters especially in your area. For systems in the high country adapters are used for frostline conditions.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
By the NEC, it's not unless you decide to use it as such. Do you agree with that statement?
Think of the impedance created by the #12 that is only accessible to the lightning by way of the feeder EGC, to the branch circuit EGC, out an average 150' of overall wire length to get to the casing.
1. You think lightning is going to prefer that path over the rod?
2. Can you imagine the collateral damage throughout the home to all the other paths that are equally attractive?
Agreed.
I see it is a matter of experience in getting zapped on an old steel well system that has a case fault. The casing is not so superior as a ground rod in that instance. Please refer back to the post #17 to understand the reason for the EGC bonding.
Dear Bob and Dennis,
My apologies for reading past this...now I see what you were saying.
OK maybe we can take this one thing at a time.
you're saying that there should be a ground rod to ground the well casing?
you're saying that there should be a ground rod to ground the well casing?
If you own a copy of the NEC....try [250.53(A)(2)] (well casing as a pipe or rod electrode) the H2O pipe shall be supplemented. Exc. 25 ohm compliance in this instance.
An EGC bonding for a well casing is what was originally referred to for the OP's question and your wanting to understand why the casing is not a superior ground electrode in true code terms.
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