Not clear whether you mean the supply side or the load side of the transformer, or both. They are both covered by NEC 760: Fire Alarm Systems.
As suggested by Rick Napier, the transformer (as a listed component) can only (legally) be installed according to the manufacturer's instructions, which are incorporated by reference into its "listing" and label, in addition to following NFPA 72, specifically 10.6.2, citing the NEC. You would start with the installation instructions for that specific panel or power supply.
Assuming it includes an equipment grounding conductor, the NEC does not permit "connection devices or fittings that depend solely on solder" for that. NEC 250.8(B).
The people who designed and tested the unit are usually the only ones who ever read the applicable UL or other standards for that type of device, i.e., UL 864 or UL 1481 or equivalent, at least until something bad happens.