Arkadaşlar,
Bence bu tartışmaya ilgili yönetmeliklerin referanslarının yanı sıra güncel IEEE 142 standardını kaynak alarak farklı bir yön verebiliriz.
IEEE 142 standardının tam metin hali bende yok. Ancak standard ile ilgili daha öncede ulaştığım makalelerden birinde, konumuz ile ilgili bazı bölümler var. Makale İngilizce ve linki;
IEEE Standard 142: Foundation for Grounding
Bu makaleden konumuz ile ilgili bölümler ise kısaca;
According to the standard, copper-clad steel isn't the best choice of ground rod material. The copper can cause severe corrosion of nearby structures if used in the wrong application.
One misperception people have is that the copper coating results in a lower resistance to earth. In fact, there is no measurable difference in earth resistance if you use galvanized or stainless rods instead of copper-clad. This fact is apparent when you look at the formulas for calculating earth resistance - the rod material isn't even a consideration.
This chapter points out the fallacy of the popular notion that the NEC favors ground rods. What gives you protection is bonding.
To maximize equipment protection, form your grounding electrode system by bonding together certain items first (see sidebar, above) and then consider supplementing it with ground rods. Doing this right means a lower cost of installation and a better grounding system.
One impetus for developing this chapter is the misunderstood "isolated ground." The standard states, "there is no real isolation between electrodes." It goes on to say the earth has a resistance, and you must consider the earth an electrical element (e.g., impedance) in an electrical circuit.
The standard states that "there is always a current flowing in the earth, which produces voltage differences in electrodes - even a few feet apart. Not only are there differences, but these differences vary from second to second, particularly in an electrical storm."
Sidebar 2: Building a Grounding System
When you design a grounding system, use these items first and bond them together:
1. Metal underground water pipe,
2. Metal frame of the building (where effectively grounded),
3. Concrete-encased electrode, and
4. Ground ring.
If these items aren't available, Standard 142 says, "then and only then can you use any of the following:"
1. Other local metal underground systems or structures,
2. Rod and pipe electrodes, and
3. Plate electrodes.
Üyelerimizde IEEE 142 standardının güncel hali elinde olan varsa, paylaşırsa çok sevinirim.
