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NEC 700.3(f) Code Change
In 2017, a new provision was added to the NFPA’s National Electric Code® (NEC®). The new provision 700.3(f), legally requires the ability to connect a temporary source of power for emergency system. This system shall rely on a single alternate source of power which can be disabled for servicing or maintenance. The most common way of fulfilling this is a Tap Box. 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. Applications that may apply to the code: Hospitals, Healthcare facilities, Public Communications, places of large assembly (including hotels, theaters, sports arenas, etc.) and industrial processes where the interruption of power would create serious health hazards.

Typical Load Bank Hookup
Tap Box Used in Application:
Typical Temporary Generator Hookup
Tap Box Used in Application:
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