Voltage Drop Formulas and DC Cable Charts

Single-phase VD = A ft 2K/C.M.
Three-phase VD = A ft 2K 0.866/C.M.
Three-phase VD = A ft 2K 0.866 1.5/C.M.( for two pole systems)
where A = amperes
L =	distance from source of supply to load
C.M. =	cross-sectional area of conductor in circular mills:
K =	12 for copper more than 50 percent loading
K =	11 for copper less than 50 percent loading
K =	18 for aluminum

VOLTAGE DROP CALCULATION FOR COPPER WIRES
WIRE	THHN AMPACITY	THWN AMPACITY	MCM	CONDUIT DIAMETER (IN)
2,000			2,016,252
1,750			1,738,503
1,500			1,490,944
1,250			1,245,699
1,000	615	545	999,424
900	595	520	907,924
800	565	490	792,756
750	535	475	751,581
700	520	460	698,389	4
600	475	420	597,861	4
500	430	380	497,872	4
400	380	335	400,192	4
350	350	310	348,133	3
300	320	285	299,700	3
250	290	255	248,788	3
4/0	260	230	211,600	2
3/0	225	200	167,000	2
2/0	195	175	133,100	2
1/0	170	150	105,600	2
1	150	130	83,690	1
2	130	115	66,360	1
3	110	100	52,620	1
4	95	85	41,740	1
6	75	65	26,240	1
8	55	50	15,510
10	30	30	10,380
12	20	20	6,530

24NEC ALLOWED CABLE DISTANCES FOR0240 VOLT AC OR DC CABLE-CHART...

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