Transformer/Tap Conductor Secondary Protection

[ayerforce]

Okay, somebody on here has to be older than me and remember this!
In what year (years?) did NEC article 240 and article 450 come together to require the standard protection that we almost assume will exist for transformer secondaries (450) and secondary conductors (240) today?
NFPA 70 is not retroactive in this case (right?). Thus, I need to differentiate between a RECOMMENDED revison and a REQUIRED revision to a customer's distribution system, originally installed in the mid 1970's. Here's one of several similar scenarios I found today:
200 ampere fusible switch in Saflex 240V 3ph 3-wire corner grounded delta panelboard with NON-200 fuses>>
110' of 1/0 THW copper in 1-1/2" rigid>>
50kva 240 delta x 208Y/120 transformer>>
85' of 2/0 THW copper in 2" rigid>>
Square D QO Series 42 circuit main lug only panelboard, chock full of QO120 branch circuit breakers.
I apologize for the somewhat pedantic details, but was this ever NEC compliant? No secondary protection for the transformer? No tap rule for the secondary conductors? 200 ampere protection for 1/0 copper conductors feeding the transformer primary?
The next one I found was almost identical, except they used three single phase 15kva transformers connected delta/wye via a wireway and then served a main lug only 30 circuit panelboard.
Thanks in advance!

 

[augie47]

"Okay, somebody on here has to be older than me"
You rang ???

Unless it's hidden elsewhere, the install you describe would not have been allowed in the 1971 NEC.
1971 240.15 required OCP at the point of supply with the transformer exception limited to 25' primary + secondary
and 384.16 required main OCP on L&A panelboards such as the one you describe (similar wording to 408.36 now)

 

[ayerforce]

Great info. Thanks for the quick response!

 

[kwired]

Three wire delta to three wire delta would be able to have primary side protection only, but of course with the 208/120 secondary you don't have that.