How to Construct STM Static Electricity Grounding Wires and Equipment Grounding Wires
I. Overall Layout Design of Grounding Electrodes The overall layout design of anti-static grounding electrodes should be determined according to the terrain, topography, soil quality, etc. There is no fixed rule; it should be designed according to specific conditions. The following methods are provided for reference. There are vertical, horizontal, and mixed layout methods.
1. Vertical Grounding Methods for Anti-static Grounding: These include straight, cross, and herringbone shapes. It is particularly important to note that the distance between each vertical grounding electrode should not be less than 5 meters; otherwise, it will have a shielding effect, reducing the resistance reduction effect. This method only involves applying a resistance-reducing agent around the vertical grounding electrode as shown in the diagram (installation of vertical grounding electrodes). This method is suitable for narrow terrain but where deep excavation is possible or mechanical drilling is feasible.
2. Horizontal Grounding Methods for Anti-static Grounding: These also include straight, cross, and herringbone shapes. No vertical grounding electrodes are installed; only horizontal grounding electrodes are installed, and a resistance-reducing agent is applied around them as shown in the diagram (installation of horizontal grounding electrodes). This method is less effective and is best avoided. However, in situations where the terrain is wide but the geological conditions are unsuitable for deep excavation and mechanical drilling is unavailable, this method must be used, but the grounding electrode should be extended as much as possible.
3. For mixed-method anti-static grounding projects, the horizontal connecting wire should also be dug as deep as possible to form a horizontal grounding electrode, and a resistance-reducing agent should be applied around it. A resistance-reducing agent should also be applied around the vertical grounding electrode simultaneously.
This method is suitable for situations where the terrain is narrow and deep excavation is inconvenient. The depth of both horizontal and vertical grounding pits can be appropriately shallower than the specified value.
Finally, it should be noted that the above construction methods are for general projects; for some large or advanced technology projects, large grid-like grounding networks are often used, or even grounding networks composed of precious metals. In such cases, resistance-reducing agents can be applied around the metal grounding electrodes in the original grounding network according to the following diagram (installation of vertical grounding electrodes) or the following diagram (installation of horizontal grounding electrodes) to meet the resistance reduction requirements.
II. Construction Method for Anti-static Grounding Projects 1. On-site, mix the resistance-reducing agent with water at a ratio of 3:2 to form a paste. Immediately pour the mixture into the pit where the grounding electrode has been placed, then fill it with fine soil and compact it.
2. Construction of Anti-static Grounding Projects: When using resistance-reducing agents on vertical grounding electrodes in anti-static grounding projects, if mechanical drilling is not possible, the outer diameter of the grounding electrode to which the resistance-reducing agent will be laid can be predetermined. A steel pipe can be fabricated as an outer mold and placed in a manually excavated large-diameter grounding pit (as shown in the diagram). Place the grounding electrode in the center of the steel mold, ensuring they are in a vertical position. Backfill the outside of the steel mold with fine soil, prepare the resistance-reducing agent, pour it between the steel mold and the grounding electrode, and then use a crane to pull the steel mold upwards. Then water and compact it. III. Measurement of Anti-static Grounding Projects: 1. After backfilling and compacting the resistance-reducing agent, the resistance value can be tested. Over time, as the soil settles, the resistance value will tend to decrease.
2. Measurements should not be performed parallel to the horizontal grounding electrode; instead, the measuring line and measuring grounding electrode should be drawn perpendicular to it. Avoid conductors and magnetic fields such as rivers, underground metal pipes, and high-voltage transmission lines as much as possible. If avoidance is not possible, the measuring line should be drawn perpendicular to them.
3. For extremely poor soil conditions (such as soil consisting entirely of rocks) or extremely narrow construction sites where it is impossible to install sufficient grounding electrodes, or when the resistance value of the measurement path is extremely high, the requirement for the qualified grounding resistance value should be reduced. If necessary, it may also be considered to drill deep holes and fill them with a resistance-reducing agent at the auxiliary measuring electrode so that the measurement results more accurately reflect the true value.