Smoke detectors in sub stations

[Hassel4]

Are smoke detectors required in sub stations? I understand it depends, so let's take two settings. These are double-ended sub units (13,800 to 480 volt), dry type and gas filled 1500 kva transformers.
The first setting has sub units in a walled concreate room, no sprinklers (1950s vintage).
The second have the sub units in mechanical space behind fencing, sprinkled.

 

[ron]

You need to review the Fire Code that is enforced in your jurisdiction at the time that the electrical permit was initiated. That will give you some direction.