Why UL1008 Certified Transfer Switches Are More Important Than Ever

With an increasing need for emergency backup power systems in hospitals, healthcare facilities, data centers, and other public facilities, it is crucial to have transfer switches that ensure reliability and safety.

Underwriter Laboratories (UL) conduct rigorous independent research, analyze safety data and risks, and develop standards to help safely commercialize technologies. The UL 1008 standard, created in 1970, sets rigorous safety standards for transfer switches in emergency power systems.

To meet the UL 1008 standard, transfer switches are tested as complete assemblies for performance endurance, safety, and reliability by an independent testing and certification agency. They are evaluated in accordance with Articles 517 (healthcare facilities) and 702 (optional standby systems) of the NEC (ANSI/NFPA 70) and the NFPA for healthcare facilities (ANSI/NFPA 99). Today, most healthcare facilities and facilities with legally required emergency power generally only accept UL 1008 transfer switches.

The performance of emergency power systems and their components, such as transfer switches, is so critical to safety that the 2017 National Electrical Code^® (NEC) includes a new provision outlined in Article 700.3(F) for emergency systems:

“If the emergency system relies on a single alternate source of power, which will be disabled for maintenance or repair, the emergency system shall include permanent switching means to connect a portable or temporary alternate source of power, which shall be available for the duration of the maintenance or repair.”

To meet this provision, you can use a UL 1008 listed POWERTRON MTS (manual transfer switch) when switching from a permanent source of power to an alternate source.

The new provision also states that:

1. Connection to the portable or temporary alternate source of power shall not require modification of the permanent system wiring.
2. Transfer of power between the normal power source and the emergency power source shall comply with 700.12.
3. The connection point for the portable or temporary alternate source shall be marked with the phase rotation and system bonding requirements.
4. Mechanical or electrical interlocking shall prevent inadvertent interconnection of power sources.
5. The switching means shall include a contact point that shall annunciate at a location remote from the generator or at another facility monitoring system to indicate that the permanent emergency source is disconnected from the emergency system.

Manual switching is permissible for switching from the permanent source of power to the portable or temporary alternate source of power, as well as for connecting a load bank.

For more information, contact RONK to learn more about our POWERTRON MTS (Manual Transfer Switch) and how it may meet your application needs.

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