NEC 700.3(F) Requires Alternative Back-Up Power While Servicing the Main Generator
NEC 700.3 (F) – is a new code added to address repair of the emergency system. This new section was added in order to make certain that emergency systems remain in action when the main emergency source is taken offline for service, maintenance or testing.
This update legally requires the installation of a permanent channel to connect an alternative power source such as a portable generator, as back-up when the main generator is offline. See an excerpt of the code below:
(F) TEMPORARY SOURCE OF POWER FOR MAINTENANCE OR REPAIR OF THE ALTERNATE SOURCE OF POWER.
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. The permanent switching means to connect a portable or temporary alternate source of power shall comply with the following:
- Connection to the portable or temporary alternate source of power shall not require modification of the permanent system wiring.
- Transfer of power between the normal power source and the emergency power source shall be in accordance with 700.12.
- The connection point for the portable or temporary alternate source shall be marked with the phase rotation and system bonding requirements.
- 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 or temporary alternate source of power and to utilize the switching means for connection of a load bank.
In order to fulfill this requirement, mission critical facilities are instructed to have a transfer switch installed in order to switch to an alternative back up power solution when needed. Once the transfer switch and generator connection cabinet has been installed, renting a portable generator is all that is needed to back up the emergency system when the main generator needs to be offline for testing or maintenance.