SAES-T-795 PDF – Communications Facility Grounding Systems

This article is about SAES-T-795 which is about Communications Facility Grounding Systems and download SAES-T-795 PDF for telecommunication and electrical engineers, supervisors and project managers, telecom QCs, telecom QC Supervisors. This is saudi aramco standards of Telecommunication Engineering based on international codes and standards and useful for telecom and electronics engineering knowledge to get job as engineers, QC Supervisors and QC managers, Engineering managers and technicians.

SAES-T-795 PDF Download

SAES-T-795

Communications Facility Grounding Systems

The SAES-T-795 standard of Saudi Aramco covers the mandatory requirements for the design and installation of communications grounding systems. It specifically addresses the grounding systems for electronic, analog, and digital telecommunications facilities, as well as remote digital switching terminals and repeater sites. The standard also applies to the upgrading of existing facilities when new equipment is being added.

The purpose of SAES-T-795 is to ensure that proper grounding systems are implemented to maintain the integrity and reliability of the communication infrastructure. Grounding systems are crucial for mitigating electrical hazards, preventing damage from electrical surges, and ensuring the proper functioning of equipment.

Industry Codes and Standards for SAES-T-795

The SAES-T-795 standard for communications grounding systems in Saudi Aramco facilities references several industry codes and standards to ensure compliance and best practices. These codes and standards are as follows:

1. National Fire Protection Association (NFPA)

• NFPA 70: National Electrical Code (NEC)
• NFPA 780: Standards for the Installation of Lightning Protection Systems

1. Building Industry Consulting Service International (BICSI)

• Telecommunications Distribution Methods Manual (TDMM)

These industry codes and standards provide guidelines and requirements for electrical installations, grounding systems, lightning protection, and telecommunications distribution methods. By incorporating these recognized standards into SAES-T-795, Saudi Aramco ensures that its communications grounding systems meet industry best practices and safety standards.

Design Requirements

The design requirements for communications facility grounding outlined in SAES-T-795 include the following:

4.1 Communications Facility Grounding:
4.1.1: Each communications facility should have one common grounding system.
4.1.2: Single-point Ground Systems (SPG) should be implemented, where the positive battery, circuit ground, or discharge ground does not contact other grounds except at a designated single point. Reference is made to Standard Drawing AA-036391.
4.1.3: All ground conductors, straps, and connections should be installed in a manner that directs fault current or lightning from its source to the grounding electrode system.

4.2 Grounding System Components:
The major components of the grounding system include:

• Grounding Electrode System
• Master Ground Bar (MGB)
• Floor Ground Bar (FGB)
• Vertical Equalizer (VE)
• Horizontal Equalizer (HE)
• Noncoated Building Steel
• Computer Floor Grounding
• MDF/Entrance Cable Protector Ground Bar (ECPGB)
• Cable Shield/Cable Vault Ground Bar (CVGB)
• Waveguide Entrance Ground Bar (WEGB)
• Grounding Conductor (GC)

These components play a crucial role in establishing a robust grounding system for electronic, analog, and digital telecommunications facilities. They ensure proper grounding of equipment, protection against electrical faults and lightning, and provide a common reference point for grounding within the facility. The design and installation of these components should adhere to the requirements specified in SAES-T-795 to ensure effective and safe grounding of the communications infrastructure.

Master Ground Bar (MGB)

The Master Ground Bar (MGB) is a key component of the grounding system in a communications facility, as specified in SAES-T-795. Here are the design requirements for the MGB:

4.2.2.1: The MGB should be a copper ground bar with a minimum size of 6 mm x 102 mm x 500 mm. All grounding connections to the MGB should be made using two-hole approved copper terminal lugs.

4.2.2.2: There should be only one MGB for each communications facility. It should be located as close as possible to the AC service and the main distribution frame of the outside plant, without interfering with cable structures and support. The location of the MGB must be clearly identified on building drawings, equipment layout plans, and on the bar itself.

4.2.2.3: The MGB should be bonded to the building ground grid (AC power ground) through two buried leads from opposite sides of the ground grid. These leads should be a minimum of 4/0 AWG (120 mm²) bare tinned-copper conductors. When routing the leads, large radius bends should be used to maintain an acceptable bending radius. The leads should be run in PVC conduit, which should be resistant to ultraviolet rays if exposed to sunlight.

4.2.2.4: Direct bonding of communications equipment within the building to the building ground grid is not allowed. Instead, the communications equipment should be bonded to the building ground grid through a single point at the MGB. The MGB serves as the common point of grounding connection for both the DC and communications equipment. The AC distribution system ground should not be connected to the building ground grid through the MGB.

4.2.2.5: The MGB should be divided into the following zones:

• P surge producers: This includes interior radio equipment (including cable trays connected to radio equipment), Cable Shield/Cable Vault Ground Bar, and MDF/Entrance Cable Protector Ground Bar.
• A surge absorbers: These are the two ground leads coming from opposite sides of the ground grid, which are bonded to the MGB.

These requirements ensure that the MGB is properly sized, located, and connected within the communications facility, facilitating effective grounding and protection against electrical faults and surges.

In addition to the zones mentioned previously, there are further requirements for the Master Ground Bar (MGB) as specified in SAES-T-795:

• N non-isolated equipment: This zone includes equipment such as the DC Power system positive return bus, computer floor, communication racks, and cable trays.
• I isolated equipment: This zone encompasses electronic switching equipment, transmission systems, and terminal equipment.

These zones should be clearly labeled on the MGB itself and on the building drawings to ensure proper identification.

Commentary Notes:

1. It is recommended to place the isolated equipment zone as far away as possible from the surge producer zone to minimize the risk of surge interference.
2. The MGB should not have any additional leads connected to it for purposes other than those specified in the standard. The MGB should not be located in the cable vault.

Furthermore, any communications equipment located outside the communications building, such as communication towers and waveguides, should be directly bonded to the AC ground grid outside the building. This ensures proper grounding and protection for equipment in outdoor installations.

These guidelines help establish a comprehensive and effective grounding system for communications facilities, ensuring the safety and reliability of the equipment and minimizing the risk of electrical issues or surges.

The SAES-T-795 standard provides specific requirements for the Floor Ground Bar (FGB), Vertical Equalizer (VE), and Horizontal Equalizer (HE) as follows:

Floor Ground Bar (FGB):

• Each floor of the communications building should have one FGB for every 60 x 60 m² equipment area. If the distance between the MGB/FGB and the equipment exceeds 40 m or if the equipment floor area exceeds the specified limit, additional FGBs should be provided.
• The location of the FGBs must be identified on the building drawings and equipment layout plans, taking into consideration the cable support requirements.
• The minimum size of the FGB should be 6 mm x 102 mm x 500 mm. All connections to the FGB should be made using two-hole connections.

Vertical Equalizer (VE):

• VE is used to equalize the ground potential in a vertical direction across the building when the communications equipment is located on different floors.
• VE is an insulated copper conductor with a minimum size of 750 MCM (thousands circular mils) or 400 mm². It should be directly bonded to the FGBs at each floor level.
• The VE should be installed as straight as possible without offsets, and unavoidable bends should have a minimum turn radius of 900 mm.

Horizontal Equalizer (HE):

• HE is used to equalize the ground potential from the MGB/FGB appearance to the FGBs on the same floor, if installed.
• Multiple VEs should be bonded by HEs, which should be made of a minimum 750 MCM (400 mm²) insulated copper conductor.
• The HE should be installed as straight as possible, and unavoidable bends should not exceed 90 degrees with a minimum turn radius of 900 mm.

These requirements ensure proper grounding and equalization of ground potential within the communications building, promoting effective grounding practices and minimizing potential electrical issues or discrepancies in ground potential.

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