Generator and Automatic Transfer Switch Surge Protection

How to Surge Protect Generator and ATS

Service Entrance Disconnect/Utility Feed at Transfer Switch: TPX-1S240-F-150

Downstream Breaker Panels: TPX-1S240-F-100

Protecting a generator and an automatic transfer switch (ATS) begins at the service disconnect. Installing the TPD-150 at the service disconnect provides the first layer of surge protection for the entire facility, including the sensitive electronics inside the ATS.

When generator power comes online, it must be treated as a separate surge pathway. For this reason, a second surge protector, the TPX-100, should be installed at the ATS to protect generator power as it enters the facility. If there is a long outdoor run to the generator where lightning energy can couple into the conductors, or if the generator contains sensitive charging boards and control electronics, an additional unit can be installed directly at the generator for enhanced protection.

Downstream breaker panels then receive the final layer of protection. This layer not only captures any external surges that may bypass upstream devices, but also suppresses the nearly 80% of surges generated inside the home or facility, completing a multi-stage protection strategy that consistently performs best.

Finally, the low-voltage control wiring between the generator and the ATS should also be surge protected. This communication wiring is often the weakest link in the system and is frequently the first component damaged by lightning-induced surges.

This document illustrates the protection locations discussed above: Surge Protect Generators and Transfer Switches

For High Exposure Areas:

Generator Feed at Transfer Switch: TPX-1S240-F or TPX-1S240-CN

Generator: TPX-1S240-F or TPX-1S240-CN

Transfer Switch Output: TPX-1S240-F or TPX-1S240-CN

Installation Note
Depending on the location of the transfer switch, it is recommended in high exposure areas to protect any data line coming from the transfer switch to the home’s network. SPDs should also be placed between the generator and utility inputs and the ATS output. Installing protection upstream from the ATS will protect the circuit boards and power supplies within the ATS. 

NEC Requirements for Surge Protection on Generator-Fed Panels

The National Electrical Code (NEC) requires the installation of surge protection on panels and equipment for emergency, legally required standby, and optional standby generator systems. NEC Articles 700.8, 701.8, and 702.8 mandate that switchboards and panelboards connected to generator systems be provided with surge protective devices to protect downstream equipment from surges and power disturbances originating from generator operation. These requirements recognize that generator systems and automatic transfer switches contain sensitive electronics and that generator-supplied power can introduce both transient surges and power-quality disturbances. Properly installed surge protection on automatic transfer switches and all panels fed by generators is required to ensure reliable operation and to prevent equipment damage during utility outages and emergency power events.

The Importance of Generator and ATS Surge Protection

Ensure Comfort and Safety
In residential settings, generators and ATS equipment are lifelines during power outages, maintaining essential services like lighting, heating, and refrigeration. Commercial facilities rely on these systems for security and business continuity. Surge-induced failures can disrupt these critical functions, impacting the comfort and safety of individuals in both residential and commercial spaces.

Prevent Data Loss
In today's digital age, both modern homes and businesses heavily depend on electronic devices, from computers to smart home systems. Surges pose a significant threat to these devices. When applied properly, TPD surge protection shields both the generator and connected electronics, preventing data loss and preserving system functionality.

Reduce Repair Costs
Repairing or replacing generator and ATS equipment can be a financial burden. TPD surge protection serves as a guardian, mitigating the risk of electrical damage in both residential and commercial settings, helping homeowners and businesses avoid unexpected repair expenses.

Enhance Safety
Surge-induced damage can create safety hazards, including the risk of electrical fires. TPD surge protection contributes to home safety in residential contexts and ensures workplace safety in commercial environments, preventing surges from causing dangerous electrical conditions.

Prevent Costly Downtime
Downtime can result in significant financial losses. Surge-induced failures in generator and ATS systems can disrupt business operations, leading to missed production targets, customer dissatisfaction, and lost revenue in commercial settings. In residential spaces, it hampers daily life. TPD surge protection minimizes the risk of such costly disruptions, ensuring smooth operations for both homes and businesses.

Protect Critical Infrastructure
Commercial facilities often house sensitive electronic equipment, data centers, and HVAC systems that rely on uninterrupted power. Surges can wreak havoc on this critical infrastructure, resulting in equipment failure, data loss, and compromised environmental control. TPD surge protection guarantees the reliability of backup power systems, safeguarding the heart of businesses and ensuring business continuity.

TPD surge protection for generator and ATS equipment is an essential investment for both residential and commercial applications. It ensures uninterrupted power, prevents data loss, reduces repair costs, enhances safety, and protects critical infrastructure, contributing to the convenience, resilience, and cost-effectiveness of homes and businesses alike.

Why Protect All Panels Fed by Emergency Generators?

Disruption to power in facilities such as hospitals, laboratories, and data centers can be dangerous, as power is required to perform critical tasks and services. If one of these facilities loses power, and generators cannot turn on due to damage caused by surges and/or lightning, it could be harmful. Downtime becomes not only a costly consequence, but one that is life-threatening. If surges take out an ATS, the generator will not turn on at all in the event of power loss.

Additionally, generators do not always provide the cleanest power or sinusoidal waveform that electronics need to operate effectively and sustain longevity. It is not unheard of that generators have killed the very equipment they were designed to keep powered. In most cases, installing a quality surge suppressor with enhanced filtering on the electrical panel fed by the generator will protect all equipment on that panel from the dirty generator power. It is extremely important to protect automatic transfer switches so power can continue to be supplied to homes, buildings, and facilities in the midst of an emergency.

Surge Protection for Whole-Home Generators

A power outage can create major problems. To avoid those problems, you may have thought about installing a whole-home or whole-house generator. If you do, consider adding a surge protector to control the flow of power into your home. Today’s custom homes have electrical and electronic equipment similar to the lighting systems and controls, automation systems, HVAC systems, etc. found in commercial facilities, so home electrical panels have the same need of protection from dirty power originating from the use of generators.