what is the voltage drop for a no. copper wire 50 feet long to carry 12.5 amperes

Copper Wire Resistance and Voltage Drop

AWG stands for "American Wire Judge" and is a standardized wire approximate arrangement  used in the US since 1857 for diameters of round, nonferrous, electrically conducting wire.  The cross-sectional area of a wire determines it's resistance and current-carrying capacity.  The large the wire bore, the less resistance it has to the flow of electrons, and the more than current it can carry without overheating.  The table below list copper wire resistance for various gauges of copper wire.  These should be used as a rule of pollex as there are other factors that play into the current ratings of wire including ambience temperature, insulation temperature limit, air convection, etc.  You should consult the National Electric Code (NEC) for specific guidelines.

AWG Wire Sizes and Resistance

	AWG approximate	Conductor Diameter Inches	Conductor Diameter mm	Ohms per 1000 ft.
	0000	0.46	xi.684	0.049
	000	0.4096	10.40384	0.0618
	00	0.3648	9.26592	0.0779
	0	0.3249	8.25246	0.0983
	i	0.2893	7.34822	0.1239
	ii	0.2576	six.54304	0.1563
	three	0.2294	v.82676	0.197
	4	0.2043	5.18922	0.2485
	v	0.1819	4.62026	0.3133
	6	0.162	four.1148	0.3951
	vii	0.1443	three.66522	0.4982
	8	0.1285	3.2639	0.6282
	9	0.1144	2.90576	0.7921
	ten	0.1019	2.58826	0.9989
	xi	0.0907	2.30378	1.26
	12	0.0808	2.05232	1.588
	13	0.072	i.8288	2.003
	14	0.0641	1.62814	2.525
	15	0.0571	i.45034	three.184
	16	0.0508	1.29032	four.016
	17	0.0453	1.15062	5.064
	18	0.0403	one.02362	6.385
	nineteen	0.0359	0.91186	viii.051
	20	0.032	0.8128	10.fifteen
	21	0.0285	0.7239	12.8
	22	0.0254	0.64516	16.fourteen
	23	0.0226	0.57404	20.36
	24	0.0201	0.51054	25.67
	25	0.0179	0.45466	32.37
	26	0.0159	0.40386	40.81
	27	0.0142	0.36068	51.47
	28	0.0126	0.32004	64.9
	29	0.0113	0.28702	81.83
	xxx	0.01	0.254	103.2
	31	0.0089	0.22606	130.1
	32	0.008	0.2032	164.one

The diagram beneath shows many of the common copper wire sizes used when wiring a dwelling.  General ampacity ratings are listed as well but you should consult the tables below for more accurate ampacity ratings.  This illustration is meant to prove relative sizes of the common gauges of wire.

Common Copper Wire Sizes

This tabular array provides the amperage rating for common insulated conductors including Romex.  Insulated conductors should have the temp rating and blazon (i.due east. THWN 75ºC) printed on the outside of the cablevision.  Yous tin can then follow the chart below to see how much current y'all are immune to put through the usher.  This table assumes non more than three conductors in a raceway or cable or earth (direct buried) and is based on ambient temperature of 30ºC (86ºF).

Ampacities of Insulated Conductors

Size	Temperature Rating of Conductor						Size
AWG	60ºC	75ºC	90ºC	60ºC	75ºC	90ºC	AWG
	(140ºF)	(167ºF)	(194ºF)	(140ºF)	(167ºF)	(194ºF)
	Types	Types	Types	Types	Types	Types
	T TW UF	THW THWN XHHW Use	RHH THHN XHHW	T TW UF	THW THWN XHHW USE	RHH THHN XHHW
0	Copper			Aluminum
14	20	20	25	----	----	----	----
12	25	25	30	20	twenty	25	12
x	30	35	40	25	30	35	ten
8	40	50	55	thirty	forty	45	8
6	55	65	75	40	fifty	60	half dozen
iv	seventy	85	95	55	65	75	four
3	85	100	110	65	75	85	3
2	95	115	130	75	90	100	two
one	110	130	150	85	100	115	1
0	125	150	170	100	120	135	0
00	145	175	195	115	135	150	00
000	165	200	225	130	155	175	000
0000	195	230	260	150	180	205	0000
250	215	255	290	170	205	230	250
300	240	285	320	190	230	255	300
350	260	310	350	210	250	280	350
400	280	335	380	225	270	305	400
500	320	380	430	260	310	350	500

The table below provides the maximum number of THNN conductors that you tin can put in a given size conduit.  Correction factors should be used if putting more 3 conductors in a raceway.

Maximum Number of THNN Conductors in Conduit

Conduit Size (inches)
AWG	1/2	3/four	i	1 1/four	i 1/2	2	ii ane/2	3	three 1/2	4	five	half-dozen
14	13	24	39	69	94	154
12	10	18	29	51	lxx	114	164
10	6	11	18	32	44	73	104	160
eight	iii	5	ix	16	22	36	51	51	106	136
6	one	four	6	11	15	26	37	37	76	98	154
4	i	2	4	7	9	sixteen	22	22	47	60	94	137
3	1	ane	3	6	8	13	xix	29	39	51	eighty	116
2	ane	1	3	5	7	eleven	16	25	33	43	67	97
1		ane	ane	3	v	viii	12	18	25	32	50	72
0		1	i	three	four	7	10	15	21	27	42	61
00		1	i	2	three	6	8	13	17	22	35	51
000		i	one	1	3	5	7	11	14	18	29	42
0000		1	one	1	2	iv	half dozen	ix	12	xv	24	35
250			1	1	1	3	4	7	10	12	20	28
300			1	1	1	3	4	6	viii	eleven	17	24
350			1	1	1	two	3	five	7	9	xv	21
400				1	1	one	three	5	6	8	13	19
500				1	one	1	2	4	5	7	11	16

Ampacity Correction Factors for more than 3 conductors in Raceway

No. Conductors	4 to half dozen	vii to 9	10 to 20	21 to xxx	31 to forty
Factor	0.8	0.7	0.5	0.45	0.four

Why practise I need larger gauge wire to deport more current?

The larger the copper wire size the less resistance and hence the more current information technology can carry without over-heating. Resistance impedes to the flow of electrons and causes a voltage drop across the wire.  You want to avoid voltage drops on your wiring equally much as possible because they generate rut and wasted energy.  The calculator below will help determine how much voltage driblet you will get with a given copper wire and its associated resistance.

Voltage Drib Calculator

This calculator determines the voltage drib for an aluminum or copper wire of whatsoever gauge.  You lot should by and large target less than 3% voltage driblet in a given excursion. Wire resistances are based on NEC 2008, Table eight at 75^oC.

Voltage Driblet Estimator Download

The following Excel spreadsheet is a voltage drop calculator that is a piddling more avant-garde.  It can be used to make up one's mind recommended wire gauges, maximum distances, or maximum amperage.

Voltage Drop Calc (.xls, 650KB)

Grounding Conductor Size Calculator

Select rating of circuit breaker ahead of equipment, conduit, etc. Not Exceeding (Amperes)
Required size of Copper grounding conductor	Required size of Aluminum grounding conductor
*Calculator based on 2008 NEC Tabular array 250-122.  Calculator specifies minimum size grounding conductors required for grounding a raceway or equipment. Do not utilize this calculator for sizing hot conductors.

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Source: https://www.buildmyowncabin.com/electrical/copper-wire-resistance.html

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