The sizing is also dependant on how knowledgable the person requesting it is.
I've had experienced phone guys ask for #6, but the hotrod "I'm the HEAD of this company's IT Department" just told me yesterday that he thought that the #2/0 that he requested during the initial design wouldn't be big enough and is whining that it should be changed out to be larger. The less these folks know, the more that they're likely to blame their problems on 'improper grounding'. Heck, these are the same folks who invented cutting off the ground plug on the equipment to 'solve' the noise problems on their little networks.
What's located in this room? A single 19" rack, a third filled with patch panels and 1 router.
Where's it located in their existing building? In a storage room plugged into an extension cord and working just fine.
BTW, I get the same grief about isolated grounds for computer equipment when it's just a standard PC. I always ask if they have a PC at home; do they have an IG receptacle at home; and why do they think that what works at home won't work in the office.
