kevinengineer99
Member
- Location
- usa
- Occupation
- engineer
What is the best location for lightning protection "test well"? At the corner of the building? Or does it need to be close to the main electrical room? Thanks.
Where to put lightning protection "test well"?
- Thread starter kevinengineer99
- Start date
- Status
- Location
- Illinois
- Occupation
- retired electrician
What is a lightning protection test well?
ptonsparky
Tom
- Occupation
- EC - retired
Always something new to learn about.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Here's one of two we installed on the grounding ring at an outdoor cell site.
I think it's so they could test the impedance with a clamp-on ground tester.
- Location
- Illinois
- Occupation
- retired electrician
The grounding test wells I have worked with had a mechanical connection to the electrode so that you could test the ground resistance of the electrode itself.
Not sure if a "lightning protection test well" is the same thing.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
I had to google it. Appears to be a concrete or steel handhole to give access to the ground ring conductor.
kevinengineer99
Member
- Location
- usa
- Occupation
- engineer
Yes that's what I meant. For a new building, what's the best place for it? At building corner? Or outside the main electrical room? Thanks.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
I suggest putting it where you will get the worst case readings.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Whomever designed the system should have, and should provide that info.
For testing, I think one needs access to a ground rod, and access to outdoor soil for a probe, so my money would be on putting it outside.
Unless you can isolate parts of the grounding electrode system, shouldn't all the readings be about the same?
Unless you can isolate parts of the grounding electrode system, shouldn't all the readings be about the same?
fbhwt
Electrical Systems Inspector
- Location
- Spotsylvania,Virginia
- Occupation
- Electrical Systems Inspector
Depends on what type of lightning protection system installed, Catenary, Integral, or Mast-Type. Test wells are usually required when the system electrodes or ground loop are required to be tested. Test wells are used so that the driven electrode can be isolated from the rest of the system. Some systems; systems without a ground loop have a down conductor that attaches directly to the driven electrode. NFPA 780 says that the down conductor "shall be attached permanently to the grounding electrode system by bolting, brazing, welding, or high-compression connectors listed for the purpose".
NFPA 780 also says if you have a lightning protection system installed: "A ground bar designed for interconnection of building grounded systems shall have one connection to the lightning protection system."
It would seem to me if the connections were all permanent (brazed, welded) the test well would be useless except for knowing where your driven electrodes were located.
The systems I work on require me to do a 3-point fall of potential on the driven electrode every two years. When a new system is installed the installer should provide the customer with a "master label certificate" which is good for five years unless there is new construction, addition to the structure.
Still the overall ground resistance of the lightning protection system may be measured and compared with the standard value, if any.
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