Referring this clause
"NFPA 850 22.214.171.124* Unless consideration of the factors in 126.96.36.199 indicates otherwise, it is recommended that any oil-insulated transformer containing 500 gal (1893 L) or more of oil be separated from adjacent structures by a 2-hour–rated firewall or by spatial separation in accordance with Table 188.8.131.52. Where a firewall is provided between structures and a transformer, it should extend vertically and horizontally as indicated in Figure 184.108.40.206."
Is this applicable also between Emergency Diesel Generator/equipment and Transformers?
Since as mention in the clause "between structures and a transformer" only.