I ran across an interesting statistic the other day. The Electric Power Research Institute (EPRI) says that “better than 80% of all electronic system failures that are attributed to power anomalies are actually the result of electrical wiring or grounding errors or are generated by other loads within the customer’s facility.”
In electronic circuit theory, a ground is defined as an infinite source or sink that can absorb an unlimited amount of electricity. The National Electric Code requires grounding to mean a connection to the physical ground (earth) that can limit the voltage during a lightning strike or due to contact from a high-voltage electric line. The NEC also requires that “the earth shall not be used as the sole equipment-grounding conductor.”
We all take grounding somewhat for granted. When a new telecom structure is built that will house electronics, an engineer typically signs off on a grounding plan. We didn’t use to have to worry as much about grounding because most buildings had metallic water pipes that acted as the primary grounding electrode for a building. But most pipes are now PVC, and we’ve lost the natural grounding for new buildings.
Properly grounding electrical systems is vital to protect telecom electronics and people working in a building. When a building is not properly grounded, conductive surfaces inside the building can become electrically energized and can create a fatal shock.
Grounding isn’t only to protect against lightning strikes. A lot of electric grids occasionally send a surge of power through the lines that probably go unnoticed. These surges can be deadly to sensitive electronic cards and systems.
Properly grounding a building, hut, or tower site can protect equipment and staff against anomalous electric events. Good grounding can:
- Make sure that all circuits have an effective return path between all electronics and the power source.
- Ensures that low resistance is provided in all circuits to make it easier to trip or short a circuit breaker in the event of an electrical fault.
- Make sure that metallic components are electrically connected in a way that prevents a voltage connection between them.
- A common ground (zero-voltage reference point) is established as the primary connecting to external grounding.
The advantages of proper grounding are fairly obvious and include
- Eliminating shock hazards for staff.
- Protecting electronics from voltage surges.
- Preventing electrical fires.
- Increasing the life of electronics.
- Reducing repair costs and downtime.
- Lowers the level of electrical noise, which are fluctuations in the electric current.
I’ve had clients over the years who have solved mysterious and anomalous electric problems by conducting a grounding study and then fixing shortfalls in the grounding. When a given site continues to have unexplained problems, looking at the grounding is a smart part of the investigation.
In addition to its importance for commercial customers and broadband providers, proper grounding is also important in residential applications. Though many are aware of power surges and try to protect their home and electronics with surge protectors, homes with copper broadband service such as traditional cable and DSL are susceptible to surges that can enter the home through the broadband network connection. Yes categorizing DSL as broadband is a bit of a stretch, but technically it is a broadband technology.
I have been fortunate enough to live through this adventure in two different homes… one with cable and the other DSL. Surges can be induced in the cable or DSL shield conductor by a nearby lightning strike. This is especially true in rural DSL applications where the buried DSL cable may travel many hundreds of feet from the nearest pedestal to the home.
Without proper grounding at the home’s demarcation/egress location, this surge will travel in and toast the attached modem. Once the surge hits the modem it can then travel to any ethernet attached device and cause damage… routers, switches, TVs, computers, Roku players, A/V receivers, etc. Though I know better, it typically takes an “event” and loss to make a homeowner aware of a problem.
Unfortunately it is not really feasible to provide surge protection on the broadband connection to a home. Though such devices exist, they typically attenuate the incoming signal to unacceptable levels… especially for rural DSL. It is critical to ensure that the demarcation point of the copper broadband service connection is properly grounded, which includes tying this ground back to the electrical system ground at the service entrance of the home.
Even with proper grounding, there is still potential for surge damage through a copper broadband connection. In a rural setting, homeowners and businesses should consider optical isolation between the modem and the rest of their network as extra insurance.