Emergency Generator 2hr Ratings

[tkb]

When wiring an emergency generator, 700.10(D)(3) requires that the control wiring comply with 700.10(D)(1), this is also true for the generator feeder wiring.
700.10(D)(1) requires that the wiring be 2hr rated.

If the ATS is located in a 2hr rated room, 700.10(D)(2), and the generator is outside of the building, and the wiring is underground from the ATS in the 2hr rated room to the generator, does this wiring have to be 2hr rated?

Would the conduits to the emergency generator have to be 2hr rated or concrete encased, or because this is outside the building a 2hr rating is not required?

If a 2hr rating is not required because it is outside the building, is there a code reference?

Also, what’s up with the change in 700.1(D)(3) to monitor the control wiring?
Is that a generator manufacturer issue?

 

[texie]

When wiring an emergency generator, 700.10(D)(3) requires that the control wiring comply with 700.10(D)(1), this is also true for the generator feeder wiring.
700.10(D)(1) requires that the wiring be 2hr rated.

If the ATS is located in a 2hr rated room, 700.10(D)(2), and the generator is outside of the building, and the wiring is underground from the ATS in the 2hr rated room to the generator, does this wiring have to be 2hr rated?

Would the conduits to the emergency generator have to be 2hr rated or concrete encased, or because this is outside the building a 2hr rating is not required?

If a 2hr rating is not required because it is outside the building, is there a code reference?

Also, what’s up with the change in 700.1(D)(3) to monitor the control wiring?
Is that a generator manufacturer issue?

As you describe the installation of within the 2 hour room, underground and outside, that wiring would not have to be 2 hour rated.
The control wiring change you mention, I think you meant 710.10(D)(3). Yep this is kinda of big change after all these years of a simple open or closed 2 wire circuit. And I think a good change.. This will be a genset manufacturer issue. I'm guessing they will redesign the 2 wire start circuit to incorporate an end of line resister at the ATS end so that an open or short will cause the genset to start regardless if the start contacts in the ATS are open or closed. Similar to a supervised alarm circuit. With the modern electronic controllers used on NFPA 110 certified gensets today I don't think this will be hard for them to incorporate.

 

[tkb]

As you describe the installation of within the 2 hour room, underground and outside, that wiring would not have to be 2 hour rated...

I agree, but is there a code article that would confirm this?
Article 700.10(D)(1) does not have an exception for circuits outside the building or underground.

 

[shortcircuit2]

700.10(D)(5) calls for encasement by a minimum of 50 mm (2 in.) of concrete. IMO this applies to feeders outside a building and underground.