Yeah...
If you flip your main and can't reset it, you need to replace it. There shouldn't be ANY part of your electrical system that you can't operate safely and reliably.
Technically, the NEC does allow it to be run. You still have to figure the areial ratio and size it appropriately though.
There are several situations where I can see a logistical usage of NMB inside of conduit, but in general I would highly advise an alternative. My top two reasons are ease...