Last Updated on August 10, 2021
As you may know, the Rosetta stone was the key to translating ancient Egyptian Hieroglyphics. It had the same message written in Ancient Greek, a more recent Egyptian script and ancient Hieroglyphics and that was the key to understanding the long-dead language of classical Egypt.
While the National Electrical Code (NEC) is not written in Hieroglyphics, the language can be somewhat dense and the practical meaning isn’t always crystal clear. In particular, the new requirements added to Sections 700.3 and 702.12 in 2017 and 2020 are of interest to anyone responsible for installing or maintaining safety-related back-up and emergency power systems.
So, with a tip of the hat to the linguists, philologists and archaeolexicoligists who may be reading this, we will attempt to translate NEC-speak into everyday English you can use to implement the Code
700.3(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:
(1) Connection to the portable or temporary alternator source of power shall not require modification to the permanent system wiring.
Translation: You can’t simply disconnect the existing wiring and hardwire the back-up generator. It’s both unsafe and time consuming. A better solution is a permanent docking station like a Trystar unit that is UL listed and able to receive a CamLock extension cable.
(2) Transfer of power between the normal power source and the emergency power source shall be in accordance with 700.12.
Translation: Back-up power has to be up and running within 10 seconds. A Trystar docking station has available options for Auto Start contacts or a Two Position Auto Start Selector Switch to ensure your back up generator is up and running on demand.
(3) The connection point for the portable or temporary alternate source shall be marked with the phase rotation and system bonding requirements.
Translation: Phase rotation and system bonding have to be identical between the primary and back-up power sources. A Trystar docking station has a phase rotation monitor and a bonding and phase rotation commissioning sheet or placard on the product for the life of the product.
An integrated phase rotation monitor is also standard. One green light indicates a correct connection. A red light indicates a mismatch and the system presents instructions on how to correct the problem
(4) Mechanical or electrical interlocking shall prevent inadvertent interconnection of power sources.
Translation: The docking station should make it impossible to parallel the permanent and temporary generator or backfeed the permanent generator, protecting the electrician or technician working on the the Generator. Trystar docking stations offer four different standard configurations that cover more than 60 percent of all common applications. Custom configurations are available to cover the rest.
5) The switching means shall include a contact point which 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.
Translation: Everyone makes mistakes, and it’s entirely possible for a technician to take a permanent generator off-line for maintenance and then re-connect it but not actually perform all of the steps required to make it available in an emergency.
Trystar’s alarm annunciator panel includes both audible and visual alarms that indicate when the primary generator is unavailable for any reason to prevent this kind of mistake.
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.
Informational Note: There are many possible methods to achieve the requirements of 700.3(F). See figure 700.3(F) for one example.
Exception: The permanent switching means to connect a portable or temporary alternate source of power, for the duration of the maintenance or repair, shall not be required where any of the following conditions exists:
(1) All processes that rely on the emergency system source are capable of being disabled during maintenance or repair of the emergency power source.
(2) The building or structure is unoccupied and fire suppression systems are fully functional and do not require an alternate power source.
(3) Other temporary means can be substituted for the emergency system.
(4) A permanent alternate emergency source, such as, but not limited to, a second on-site standby generator or separate electric utility service connection, capable of supporting the emergency system, exists.
NEC 702.12(C) Power Inlets Rated At 100 Amperes or Greater, for Portable Generators
Equipment containing power inlets for the connection of a generator source shall be listed for the intended use. Systems with power inlets shall be equipped with an interlocked disconnecting system.
Translation: Disconnecting a 100-amp connector while power is applied is very dangerous and must be prevented. Trystar docking stations use a patent-pending solenoid interlock that prevents opening the access door or accessing the connectors while the generator is running or if the camloks are energized. The access door is also alarmed to indicate if it is not fully closed. These safety features are unique to Trystar docking stations.
Exception No. 1: If the inlet device is rated as a disconnecting means.
Exception No. 2 Supervised industrial installations where permanent space is identified for the portable generator located within line of sight of the power inlets shall not be required to have interlocked disconnecting means nor inlets rated as disconnects.
NEC 700 applies to any building occupied by large numbers of people including, but not limited to, hotels, sports arenas, libraries, hospitals, nursing homes, K-12 schools, colleges, universities and many others. Trystar offers a full line of NEC 700 compliant docking stations with capacities up to 5,000 amps and SCCR of up to 65K which are suitable for both new and retro-fit applications. Go to Trystar.com for more information, or call us at 507-333-3990 to see how a Trystar Docking station fits into your new build or retrofit plans.