| Author |
Message |
David G. Axt, CCS, CSI ,SCIP
Senior Member
Username: david_axt
Post Number: 1471
Registered: 03-2002
| | Posted on Wednesday, March 23, 2016 - 12:58 pm: |    |
When should a chain link fence be grounded?
(I would assume that setting steel posts in concrete in the earth would be sufficient grounding.)
Thanks.
David G. Axt, CCS, CSI, SCIP
Specifications Consultant
Axt Consulting LLC |
George A. Everding, FCSI, CCS, CCCA, AIA
Senior Member
Username: geverding
Post Number: 824
Registered: 11-2004
| | Posted on Wednesday, March 23, 2016 - 02:27 pm: | |
Did you check the Chain Link Fence Manufacturer's Institute website? I always found them to be a good source for information when I had to write a chain link section. http://www.chainlinkinfo.org |
Mark Gilligan SE,
Senior Member
Username: mark_gilligan
Post Number: 782
Registered: 10-2007
| | Posted on Wednesday, March 23, 2016 - 07:32 pm: | |
What is driving the question?
If there is a need for grounding then you would likely need to do more than sticking the posts in the ground. It could be necessary to bond the fencing to the poles.
What does the Electrical Engineer on the project say? If there is no electrical engineer then it is likely that you do not need to do anything out of the ordinary. If there is a need for gronding an electrical engineer should be writing the technical portion of the specification. |
Michael Chusid, RA FCSI CCS
Senior Member
Username: michael_chusid
Post Number: 129
Registered: 10-2003
| | Posted on Wednesday, March 23, 2016 - 10:35 pm: | |
It may be necessary to ground a fence as part of a lightning protection system.
Don't assume the steel post in concrete is always an effective ground. The concrete itself is less conductive than the steel and the soil may have poor conductivity. Grounding terminals for lightning protection are copper and typically extend ten feet into the earth, far more than the typical fence post.
Lightning seeks the path of least resistance to earth. If that path runs through a fence to a building or a gate operator, there is a chance for damage to the structure or operator.
Tell me more about the type of project and I will try to get you more tips.
Michael Chusid, RA FCSI CCS
www.chusid.com www.buildingproduct.guru |
Guest (Unregistered Guest)
Unregistered guest
| | Posted on Thursday, March 24, 2016 - 01:23 pm: | |
I vaguely recall reading something about grounding fences enclosing electrical equipment? |
David G. Axt, CCS, CSI ,SCIP
Senior Member
Username: david_axt
Post Number: 1472
Registered: 03-2002
| | Posted on Thursday, March 24, 2016 - 02:07 pm: | |
Michael,
These fences are for my school projects The fences are either around the property, ball fields/backstops, play areas, or all of the above.
We don't get a lot of lighting in Washington state. Rain yes; lighting/thunder rarely.
David G. Axt, CCS, CSI, SCIP
Specifications Consultant
Axt Consulting LLC |
Steven Bruneel, AIA, CSI-CDT, LEED-AP, EDAC
Senior Member
Username: redseca2
Post Number: 536
Registered: 12-2006
| | Posted on Thursday, March 24, 2016 - 03:02 pm: | |
In addition to lightning strikes, grounding is required when high voltage power lines cross over the fence line and where fences enclose electrical power distribution equipment. It may be required or recommended if there are power operated gates in the fence system.
When metal fence posts are buried in the ground they may not provide a sufficient grounding, and composite fence posts certainly would not. Also, galvanized or painted finishes will effect the grounding. Grounding effectiveness is measured as a resistance to ground value in Ohms.
The current MasterSpec Chain Link Fence Section in Part 2 "Performance Requirements" suggests a maximum of 25 ohms.
In addition, MasterSpec in Part 1 - Quality Assurance provides testing agency qualifications for testing the fence system grounding; Part 2 includes "Grounding Materials"; Part 3 includes "Grounding and Bonding" installation, and Part 3 "Field Quality Control" includes grounding testing.
Note that different standards come into play. Fences Enclosing Electrical Power Distribution Equipment need to conform to IEEE requirements while bonding to a lightning protection system should conform to NFPA 780. Otherwise, the fence grounding should conform to the Project's DIV 26 grounding requirements if there are any. |
Michael Chusid, RA FCSI CCS
Senior Member
Username: michael_chusid
Post Number: 130
Registered: 10-2003
| | Posted on Thursday, March 24, 2016 - 11:46 pm: | |
I consulted a person certified by the Lightning Protection Institute as a Lightning Protection Installer/Designer. She informs me that most fences are outside of the scope of NFPA780 but fall under the NEC Article 250 and UL 467.
Regarding school playgrounds and such, the National Weather Service advises, "When Thunder Roars, Go Indoors." This is good advice for construction sites, too.
Michael Chusid, RA FCSI CCS
www.chusid.com www.buildingproduct.guru |
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