Referring this clause
"NFPA 850 220.127.116.11* Unless consideration of the factors in 18.104.22.168 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 22.214.171.124. Where a firewall is provided between structures and a transformer, it should extend vertically and horizontally as indicated in Figure 126.96.36.199."
Is this applicable also between Emergency Diesel Generator/equipment and Transformers?
Since as mention in the clause "between structures and a transformer" only.