No questions or suggestions seemed inapropriate for a volage drop thread.
On the social side, its notable that UK standard, 2008 BS7871, used formulas to accomplish its task in 400 pages vs the 2008 NFPA-70 in 800+ pages of idiot tables requiring convoluted adjustments to more cross-referenced tables.
It took me years to load these lookup-table formulas & adjustments into a spreadsheet, just to start over again in 2008, when the NEC changed Table-8 conductor properties to harmonize w/ Canadian Standards.
If I dared to learn BS7871, it might be cause enough to take a long vacation from the NFPA, become an undocumented laborer in the UK, and piss off their licensed contractors.
theory is one thing
practice another
adjustments are seldom needed, the most used I would venture is >3 cond derating
as far as temp the tables are conservative
amb is 30 C
the insul 75 C is at rated ampacity
pf 0.85
2 x D/1000 x Z x I will suffice >95% of the time
the other 5% niether std has tables for all possibilities
there are other factors
load profile, util v is usually higher, equip rated for 100% at a drop
ie, 480 motor rated at 460 or >4% drop
and table fla are usually high and motors are seldom run 100% loaded
so you may 'calculate' 3%, but it will operate lower
so if a calc is off even 30% (unlikely), 3% vs 4% does it matter?
for bldg wire moot
I look at discussion like this as mental excercise or thought provoking
not really going to change the way many do things
now v drop upon motor starting, all the way to the util xfmr
how many look at stuff like that? lol
