Grounding & Bonding Telecommunications Enclosures

Telecommunications Enclosures

When it comes to grounding and bonding, every organization and professional has their own opinions and ways of doing things.

Thankfully, the National Electric Code (NEC), Network Equipment-Building System (NEBS) and Telecommunications Industry Association (TIE) take the guesswork out of the practice and provide a framework for how to properly ground and bond telecommunications enclosures. By setting industry standards that all enclosure manufacturers must follow, these codes help ensure the safety of telecommunications workers and network infrastructure integrity–ultimately providing peace of mind to the network provider and their customers.

Let’s take a look at the standards regarding grounding and bonding.

What is grounding and bonding?

First, we need to define “grounding” and “bonding.”

According to article 100 of the NEC, ground is “the earth,” and grounding is when an electrical system is connected “to earth in a manner that will limit the voltage imposed by lightning, line surges or unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation.”

Bonding is then connecting metal parts “to establish electrical continuity and conductivity.”

Grounding and bonding are important because they work together to ensure the safety of the electrical system, which in turn helps protect workers and electrical equipment housed inside the enclosures.

 

Microsoft Teams

Grounding & Bonding Codes for Telecommunications Enclosures

National and local electrical codes provide guidelines for safely installing electrical wiring and equipment in telecommunications enclosures. These codes prevail over any bonding and grounding recommendations that come from other standards and/or guidelines.

As the graphic above illustrates, national and local electrical codes also take precedence over what are known as de facto industry guidelines, which are adopted by companies and local governments to further define best practices in that organization’s facility or the installation’s locale.

Scientific Principles of Grounding & Bonding

When designing their grounding and bonding systems, enclosure manufacturers need to take into consideration the three basic founding principles of telecommunications grounding–equalization, diversion and coupling.

Equalization means minimizing voltage potential differences as much as possible when dealing with very large energy, such as from lightning. The primary purpose of bonding is to help equalize the ground potential of equipment and eliminate static discharge between equipment.

Given the inductance of a certain length of wire, induced voltage increases as the length increases. At lightning voltages, this increase can be significant, regardless the size of wire used in bonding.

To help achieve equalization, manufacturers should use larger gauge and shorter length bonding conductors in a direct path, subsequently decreasing susceptibility to higher voltages.

At American Products, we implement equalization by designing internal ground systems into our shelters. This system includes a master ground bar (MGB) that is mounted to the shelter and is implemented per Motorola R56, American National Standard Institute and other industry standards. In addition, we offer an interior halo ground ring system that can be used in tandem with an aisle ground. The system includes H-tap hardware along the walls to bond conductive elements, e.g., HVAC vents, to equalize elements to the same ground potential and provide a safe environment for technicians and telecom equipment.

Diversion involves redirecting unwanted transient energy away from conducting paths and other areas normally used for communications.

When setting up enclosures and networks, organizations will establish communications paths that allow information payloads to enter and leave the site. While these paths are necessary for normal functions, they present the opportunity for exposure to unwanted, hostile energy.

Enclosure manufacturers can divert a large portion of that transient energy just by properly designing and locating bonding network elements and grounding systems. At American Products, we can do this through external grounding provisions.

We can add external ground provisions with a low impedance bond to the internal MGB on a cabinet or shelter. The network provider can then directly connect the external bar to the external site grounding system and connect grounding elements, e.g., cable shields from a nearby tower, to the ground system outside the enclosure. This will help divert transient energy away from communications equipment inside the enclosure.

Coupling is the third principle to consider in communications systems protection due to induction.

Two conductors are inductively coupled when they are configured in a way that a change in current through one conductor induces a voltage across the other. The magnitude of the induction is directly proportional to conductor spacing. Therefore, the proximity of communications and bonding/grounding conductors to each other should be considered as much as possible to mitigate undesirable coupling.

 

At American Products, we strive to design and develop quality telecommunications enclosures that will protect network providers’ employees, equipment and networks. We offer a variety of standard and optional features to ensure our cabinets and shelters will stand up to the elements, even lightning, for years to come.

To learn more, contact the American Products specialists at 417.323.6312.

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