Certain conditions must be observed to ensure optimal transformer installation :

The transformer room must be well-ventilated
Electrical distances must be maintained
Fire protection regulations must be respected
The dielectric volume must be factored in

Statutory constraints depend on local standards. For example, in France:

French legislation requires 3 types of protective device, which has a direct impact on the transformer itself

Environmental protection: discharges of transformer oil are strictly forbidden (decree no.77-254 of 08.03.1977)
There must be an appropriate dielectric retention system
Protection from internal faults: the method of protection is defined by the type of metering used