# wire gauge?

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trying to figure out what gauge of wire to use running from a bank of 4 s460's to a 3524 panel...any suggestions are appreciated...shane

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Re: wire gauge?
cdncam wrote: »
trying to figure out what gauge of wire to use running from a bank of 4 s460's to a 3524 panel...any suggestions are appreciated...shane

Use the voltage drop calculator listed in this post:

http://www.uwgb.edu/nevermab/voltage_drop_calculator_.xls
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Re: wire gauge?

Here’s my take on this question using the 2005 US National Electrical Code:

(1) NEC 690.8(A)(4): maximum inverter current = ((3500 VA / 85% efficiency) / 21 VDC min) = 196 A.
(2) NEC 690.8(B)(1): Conductors and overcurrent protection devices must be rated for 125% of maximum current, so 196 A x 125% = 245 A.
(3) Recommended DC input breaker is 250 A, which is next standard size up from 245 A; looks OK to me.

(4) Wire ampacity based on conditions of use (inverter max power spec based on 25 C ambient):
(a) 90 C wire corrected for 25 C ambient and two conductors run in conduit between battery box and breaker panel: Ampacity requirement = 250 A / 1.05 = 238 A; 4/0 AWG wire (260 A) meets requirement per NEC 310.16.
(b) 90 C wire corrected for 25 C ambient, derated for 75 C breaker terminal spec and “free air” (not in conduit) connection to breaker: Ampacity requirement = 250 A / 1.05 = 238 A; 2/0 AWG wire (265 A) meets requirement per NEC 310.17.
Worst case condition of use is (a), so 4/0 wire is required. Looks like this is in agreement with recommendations from OutBack forum.

HTH,
Jim / crewzer