Redundant generator inlet & 702.5

[tortuga]

Greetings all I have have a generator with an ATS at a commercial site. The generator is ~100 Amps located outdoors. They are requesting a 50A redundant generator inlet for a portable generator that is onsite for the case when the main generator is down for maintenance and they loose power. They are aware that the 50A generator would not be able to carry the backup loads and that they would have work the ATS manually and flip breakers manually etc.
I believe this site falls under 'optional standby'. Can I just tap a 50A inlet to the 100A generator feeder or do I need to add another transfer switch?
Thanks in advance

 

[d0nut]

Yes you can use the same feeder, but you need to make sure you can't accidentally parallel the permanent generator with your portable generator. If you don't need the portable generator to automatically start, you can just use a double throw switch. If you need to have the portable generator function the same as the permanent generator, several manufacturers make a connection box to meet the Article 700 requirements for a permanent means to connect a portable generator that work well.

 

[tortuga]

Yes you can use the same feeder, but you need to make sure you can't accidentally parallel the permanent generator with your portable generator. If you don't need the portable generator to automatically start, you can just use a double throw switch. If you need to have the portable generator function the same as the permanent generator, several manufacturers make a connection box to meet the Article 700 requirements for a permanent means to connect a portable generator that work well.

Thanks yeah the portable generator will definitely not automatically start, just for the time when the main generator is down.

 

[LarryFine]

I'd say you can not simply parallel two inlets, as the blades on the unused inlet would become energized when the other inlet is in use. Separate isolating means would be needed.

 

[tortuga]

Right thanks Larry, looks like i'll either need a doubble throw 100A switch or put a manual interlock in the backup panel.