Copper Ground Grid With Structural Steel Piles
Copper Ground Grid With Structural Steel Piles
(OP)
I am working on designing a grounding system for new 115/34kV substation. The civil engineers want to use steel piles (50' long, 9" O.D. steel pipes) to support the foundations due to difficult soil conditions. We would like to include the piles as ground rods in our ground grid analysis if possible, but we are worried about corrosion issues. Unless the copper ground gird is electrically isolated from the steel piles, will we get galvanic corrossion and lose integrity of the piles? Does anyone know of any good sources to reference when looking into this issue?






RE: Copper Ground Grid With Structural Steel Piles
Copper and steel are not that far apart on the galvanic scale.
Detailing can be found in NASA KSC-STD-E-0012E, Facility Grounding ...
The other issue would be if the steel piles are in chemically active soil, such as expansive clays. A DC bias might be suggested to prevent corrosion of the steel piles by the soil.
RE: Copper Ground Grid With Structural Steel Piles
RE: Copper Ground Grid With Structural Steel Piles
Further investigation will be needed to verify if there are safety requirements as far as needing to have the steel connected to the grid.
We have been told that it would not be feasable to coat the piles since they are going to be driven and the coating will likely be scratched off.
An impressed current cathodic protection system has been suggested, but the costs and maintenance may be an issue.
Thanks for the replies!
RE: Copper Ground Grid With Structural Steel Piles
Coordinate the dickens out of the foundation effort. The CE's see it as holding up the structure; they have no thought as to the grounding, bonding, and lightning performance.
For example, if the mat foundation is designed with post-tensioned cables, it is likely that no provision has been made for bonding the reinforcement from poles to mat to structure frame.
Those steel pipes are an electrode subsystem. And they are likely the lowest impedance path to earth.
RE: Copper Ground Grid With Structural Steel Piles
"Copper, which is the most widely used material for grounding in the United States, could cause serious dissimilar
metal corrosion to steel pipes or other steel structures. If steel conductors or rods are used for
grounding, as is the practice in many countries in the world, consideration should be given to protect this
material from corrosion due to various corrosion mechanisms that are normally found and easily attack steel
(when buried underground or submerged in an electrolyte).
Some of the most common corrosion prevention measures that are used to minimize corrosion of grounding
material and or steel piping are
a) Use of tin coated bare copper cable as a grounding conductor to minimize the potential difference
between the steel structures and the ground cable
b) Use of cathodic protection for steel grounding cables and/or piping
c) Use of insulated copper ground cable in areas near pipes
d) Electrical isolation of piping from other plant structures and the grounding system"
RE: Copper Ground Grid With Structural Steel Piles
thread238-215141: Copper-Conductor Ground Ring
There are some U.S. manufacturers of lead covered grounding cable as for instance this one:
http://ww
RE: Copper Ground Grid With Structural Steel Piles