700.3(F) is a new provision in NFPA’s 2017 National Electrical Code® (NEC®) for legally required systems. It requires provisions to be able to connect a temporary source of power for emergency systems which rely on a single alternate source of power which will be disabled for maintenance or repairs. 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 repair1.
The permanent switching means to connect a portable or temporary source of power shall comply with:
- Connection to the portable or temporary source of power shall not require modification of the permanent system wiring.
- Transfer of power between the normal and emergency sources shall not exceed 10 seconds (in accordance with NEC 700.12).
- Mechanical or electrical interlocking shall prevent inadvertent interconnection of power sources.
- 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. It shall be permissible to utilize manual switching to switch from the permanent source of power to the portable source of power and to utilize the switching means for the connection of a load bank
ESL’s TripleSwitch is 2017 NEC 700.3 (F) compliant when used in conjunction with an ATS.
Diagrams below represent TripleSwitch™ operating functions during various conditions.
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Source: NFPA’s 2017 National Electrical Code® Handbook