when did 800 amp limit for next size up come in?

[electrofelon]

Saw yet another old installation where the used next size up over 800. 10 sets of 500 CU on 4000A. Was the 800 amp cut off fairly recent or could you just do whatever you wanted in the 60's?

 

[infinity]

1965 NEC.

240-5. Overcurrent Protection of Conductors. Conductors shall be pro-
tected in accordance with their ampacity, as given in Tables 310-12
through 310-15, except as follows:
Exception No. 1. Rating of Nonadjustable Overcurrent Protection
of 800 Amperes or Less. When the standard ampere ratings of fuses
and nonadjustable circuit breakers do not correspond with the allow-
able ampacity of conductors, the next higher standard rating may be
used

 

[electrofelon]

Cool thanks!

 

[dkidd]

It would seem that the ampacity limitation of 392.80(A)(2)(b) isn't being met.