Original Post — Direct link
@ZOS_JessicaFolsom

https://forums.elderscrollsonline.com/en/discussion/575323/pc-mac-patch-notes-v7-0-5-blackwood-update-30 Itemization and item sets

Item sets that proc events that deal damage or heal now scale similarly to abilities, based on specific stats, which will now be called out in the tooltip. Check each section to see which sets scale with what! The following scaling methods are currently available, which may expand or change in the future:
Damage focused proc-based events will scale with the higher of your Weapon or Spell Damage.

***You must have 5,478 Weapon or Spell Damage to reach the original value of many sets.
Healing focused proc-based events will scale with the higher of your Max Magicka or Stamina.
**You must have 38,350 Max Magicka or Stamina to reach the original value of many sets.
Tanking focused proc-based events will either scale with your Max Health, and in some rare cases, will use the higher of your Physical or Spell Resistance.
*You must have 38,350 Max Health or 27,890 Physical or Spell Resistance to reach the original value of many sets.

***Sets that use Weapon and Spell Damage now require 6574 of either in order to reach their original values, up from 5478, resulting in approximately a 17% reduction.
**Sets that use Magicka or Stamina now require 39,901 of either in order to reach their original values, up from 38,350, resulting in approximately a 4% reduction.
*Sets that use Health now require 43,968 to reach their original values, up from 38,350, resulting in approximately a 13% reduction.
Sets that use Physical or Spell Resistance now require 30,680 of either, up from 27,890, resulting in approximately a 9% reduction.
over 3 years ago - ZOS_GinaBruno - Direct link
It should be 6,574. Sorry about that! Simply a copy paste error but it has since been updated in the patch notes.