[snickers]

What do you do when the cable your using isn't on table D3? Like 250, or 300?

trying to figure out voltage drop for an underground 400amp parallel runs.
87m approx
I know there is a formula for this somewhere in my books

 

[snickers]

I think I found my answer. If someone would be kind to verify this
Parallel runs of 250kcmil for a 400a service approx 87m (285')


L=RxCMA
-----------
K

(285x17) / 250000 = R

R = .01938ohms per conductor
.01938 x 2 = .03876ohms total
200a x .03876 = V
V = 7.752
(7.752x100) / 240 = 3.23% voltage drop
Should be okay with 250kcmil eh? :wacko:

 

[mwconstruction]

Only allowed 2% on a service.

 

[FrunkSlammer]

See note #6

(6) The distances and currents listed in Table D3 follow a pattern. When the current, for any conductor size, is increased by a factor of 10, the corresponding distance decreases by a factor of 10. This relationship can be used when no value is shown in the table. In that case, look at a current 10 times larger. The distance to the centre of distribution is then 10 times larger than the listed value.

 

[glen1971]

Never used the table... I have been using this calcualtor for over 15 years..

http://www.mc-group.ca/software_downloads.htm

We had an electrical engineer check some of the calcs and they were bang on.. It is nice because it does CEC and NEC calcualtions up to 27.6 kv and motors up to 200 hp...