New Codes for Residential Surge Protection
One of the significant additions to NEC 2020 are codes that now call for surge protection in residences. Article 230.67 stipulates that all electrical services to dwellings must have surge protection devices (SPDs) installed at or near the service entrance, and that SPDs “shall be an integral part of the service equipment or shall be located immediately adjacent thereto.”
SPDs are devices that safely intercept and discharge power surges and spikes to ground before overvoltage can damage valuable electrical equipment. Sudden surges can occur and travel along any metallic conductor and are capable of damaging, degrading, or destroying valuable electronics in the process. In fact, they are the most common cause of equipment damage.
Voltage surges a major risk
Surges can come from both external and internal sources. While dramatic, direct lighting strikes actually comprise a small percentage of external surge events. Far more common are proximity strikes, in which transient voltage from distant lightning travels along transmission lines or buried copper cabling to a facility. External surges can also occur when substation capacitors switch based on power needs or when power is restored following a brownout or blackout.
The vast majority of surges, however, are generated inside homes and commercial facilities, such as when HVAC systems, refrigerators, or other large electrical motors and equipment cycle on or off. Beyond the expense of replacing damaged electronic equipment, there is also the cost of lost data, productivity, and human safety.
A layered approach to stopping spikes
Article 230.67 of NEC 2020 specifies two types of SPDs and recommends the use of at least one of them for new residential electrical service. Type 1 SPDs are installed before the main device in the load center, while Type 2 SPDs are positioned on the load side. There is another type of SPD that is commonly in use called Type 3 SPDs; these are also installed on the load side, but closer to actual equipment or devices, such as surge protected power strips. Type 3 SPDs are not required by NEC 2020, but as part of current best practices, can still help protect sensitive electronic equipment with an additional layer of protection.
Surge protection in practice
Let’s take the example of a typical network surveillance system that includes IP security cameras. The first step is to make sure there is a Type 1 SPD at the main service entrance of the house or building as the first line of protection, with either a Type 1 or 2 SPD installed on any distribution panels within the facility. Then, we would start with the network switches at the head end and specify Type 3 surge protection on the power connections. The next step is to apply an appropriate surge protector on any network cables leaving the building or cabling that may be exposed to internally-generated surges. We would then install single channel Surge protectors close to each camera. This is because a surge can travel in either direction along a cable as it seeks a path to ground. If the SPD is at the head-end only, you risk losing the camera. With this overall layered approach, the entire system is protected from damaging electrical surges at every point where such surges could enter the system.
Compliance with NEC codes inconsistent
Despite the NFPA’s prominent role in establishing guidelines for electrical safety, NEC 2020 does not set federal or state law. States must officially adopt NEC standards themselves. As it turns out, adoption is a bit of a patchwork. According to a 2018 report by the NFPA and the Fire and Life Safety Policy Institute, the speed at which states adopt NEC codes varies significantly across the country. For example, between three cycles of NEC revisions from 2008 to 2014, approximately one third of states skipped one or more updates.
To further complicate the matter, in most cases, adoption of NEC updates happens at the state level through an official electrical board. However, in some states, adoption is left to counties or municipalities, which can put some residents at greater risk than people living in an adjacent county.
Because of this, we recommend that when it comes to protecting equipment from electrical surges, following NEC guidelines in terms of installing surge protection devices is the smartest course of action. The only way to stop a voltage surge is through proper installation of SPDs.