Voltage Drop Calculator

Voltage Drop in Long-Distance Transmission

Long-distance transmission of electrical power can result in voltage drops due to several factors, including resistance in transmission lines, inductive reactance, and the skin effect.

Factors Contributing to Voltage Drop

Resistance in Transmission Lines: The longer the transmission line, the greater the resistance it presents to the flow of electrical current, leading to voltage drops.
Inductive Reactance: Transmission lines exhibit inductive reactance, which opposes changes in current flow and contributes to voltage drops.
Skin Effect: In alternating current systems, the skin effect causes current to flow mainly near the surface of the conductor, increasing effective resistance and voltage drops.

Mitigation Strategies

To mitigate voltage drops in long-distance transmission, several strategies can be employed, such as:

Using higher voltage levels to reduce current flow and voltage drops.
Installing shunt reactors or capacitors to compensate for inductive reactance.
Optimizing line design by using thicker conductors or advanced materials.
Implementing active voltage control systems to monitor and adjust voltage levels in real-time.

Regular maintenance and monitoring of transmission lines, as well as ongoing upgrades to infrastructure and technology, are essential to ensuring the reliable and efficient transmission of electrical power over long distances.

How to Calculate Voltage Drop

To calculate the voltage drop, input the current, length, material, AWG, and type of circuit. The calculator will use the appropriate formula to determine the voltage drop.

For AC Single-phase and DC circuits:

$$ V_{drop} = \frac{2 \times I \times \rho \times L}{A} $$

For Three-phase circuits:

$$ V_{drop} = \frac{\sqrt{3} \times I \times \rho \times L}{A} $$

Example Calculation

Let's calculate the voltage drop for a copper wire (AWG 10) with a current of 15 A, a length of 50 meters, and a single-phase AC circuit.

Given:

Current, $ I = 15 $ A
Length, $ L = 50 $ m
Resistivity of copper, $ \rho = 1.68 \times 10^{-8} $ Ω·m
Cross-sectional area for AWG 10, $ A = 5.261 $ mm² = $ 5.261 \times 10^{-6} $ m²

Using the formula for AC Single-phase:

$$ V_{drop} = \frac{2 \times 15 \times 1.68 \times 10^{-8} \times 50}{5.261 \times 10^{-6}} $$

Calculating the voltage drop:

$$ V_{drop} = \frac{2 \times 15 \times 1.68 \times 10^{-8} \times 50}{5.261 \times 10^{-6}} = 4.9 \text{ V} $$

AWG to Cross-Sectional Area and Resistance

Use the table below to find the cross-sectional area and resistance for different AWG sizes:

AWG	Cross-Sectional Area (mm²)	Resistance (Ohms per 1000m)
0000 (4/0)	107.22	0.1608
000 (3/0)	85.029	0.2028
00 (2/0)	67.431	0.2557
0 (1/0)	53.475	0.3224
1	42.408	0.4066
2	33.631	0.5127
3	26.67	0.6464
4	21.151	0.8152
5	16.773	1.028
6	13.302	1.296
7	10.549	1.634
8	8.366	2.061
9	6.634	2.599
10	5.261	3.277
11	4.172	4.132
12	3.309	5.211
13	2.624	6.571
14	2.081	8.285
15	1.65	10.448
16	1.309	13.174
17	1.038	16.612
18	0.823	20.948
19	0.6527	26.415
20	0.5176	33.308
21	0.4105	42.001
22	0.3255	52.962
23	0.2582	66.784
24	0.2047	84.213
25	0.1624	106.19
26	0.1288	133.9
27	0.1021	168.85
28	0.081	212.92
29	0.0642	268.48
30	0.0509	338.55
31	0.0404	426.9
32	0.032	538.32
33	0.0254	678.8
34	0.0201	855.96
35	0.016	1,079.3
36	0.0127	1,361
37	0.01	1,716.2
38	0.007967	2,164.1
39	0.006318	2,728.9
40	0.00501	3,441.1

Material Properties

Material	Conductivity, σ (Ω⋅m)⁻¹	Resistivity, ρ (Ω⋅m)	Temperature Coefficient, α (°C)⁻¹
Silver	6.29×10⁷	1.59×10⁻⁸	0.0038
Copper	5.95×10⁷	1.72×10⁻⁸	0.0039
Gold	4.10×10⁷	2.44×10⁻⁸	0.0034
Aluminum	3.77×10⁷	2.65×10⁻⁸	0.0039
Tungsten	1.79×10⁷	5.60×10⁻⁸	0.0045
Iron	1.03×10⁷	9.71×10⁻⁸	0.0065
Platinum	0.94×10⁷	10.60×10⁻⁸	0.0039
Steel	0.50×10⁷	20.00×10⁻⁸	0.006

24V Voltage Drop Chart (3% drop)

Wire Gauge	5W (0.2 A)	10W (0.42 A)	20W (0.83 A)	30W (1.3 A)	40W (1.7 A)	50W (2.1 A)	60W (2.5 A)	70W (2.9 A)	80W (3.3 A)	90W (3.75 A)	100W (4.2 A)
22 AWG	107 ft.	52 ft.	27 ft.	17 ft.	13 ft.	10.5 ft.	9 ft.	7.5 ft.	6.8 ft.	6 ft.	5.3 ft.
20 AWG	170 ft.	85 ft.	43 ft.	27 ft.	21 ft.	17 ft.	14 ft.	12 ft.	11 ft.	9 ft.	8 ft.
18 AWG	270 ft.	134 ft.	68 ft.	45 ft.	33 ft.	27 ft.	22 ft.	19 ft.	17 ft.	15 ft.	14 ft.
16 AWG	430 ft.	215 ft.	109 ft.	72 ft.	54 ft.	43 ft.	36 ft.	31 ft.	27 ft.	24 ft.	22 ft.
14 AWG	680 ft.	345 ft.	174 ft.	115 ft.	86 ft.	69 ft.	57 ft.	49 ft.	43 ft.	39 ft.	36 ft.
12 AWG	1090 ft.	539 ft.	272 ft.	181 ft.	135 ft.	108 ft.	90 ft.	77 ft.	68 ft.	61 ft.	56 ft.
10 AWG	1730 ft.	784 ft.	397 ft.	263 ft.	197 ft.	158 ft.	131 ft.	112 ft.	98 ft.	97 ft.	82 ft.

12V Voltage Drop Chart (3% drop)

Wire Gauge	5W (0.42 A)	10W (0.83 A)	20W (1.7 A)	30W (2.5 A)	40W (3.3 A)	50W (4.16 A)	60W (5 A)
22 AWG	27 ft.	14 ft.	7 ft.	4.5 ft.	3.5 ft.	2.8 ft.	2.2 ft.
20 AWG	43 ft.	18 ft.	9 ft.	6 ft.	5 ft.	4 ft.	3 ft.
18 AWG	68 ft.	34 ft.	17 ft.	11 ft.	8 ft.	6 ft.	5 ft.
16 AWG	110 ft.	54 ft.	27 ft.	18 ft.	13 ft.	10 ft.	9 ft.
14 AWG	170 ft.	86 ft.	43 ft.	29 ft.	21 ft.	17 ft.	14 ft.
12 AWG	275 ft.	134 ft.	68 ft.	45 ft.	34 ft.	27 ft.	22 ft.
10 AWG	430 ft.	199 ft.	99 ft.	66 ft.	49 ft.	39 ft.	33 ft.

What is 3% voltage drop rule

This condition causes the load to work harder with less voltage pushing the current. The National Electrical Code recommends limiting the voltage drop from the breaker box to the farthest outlet for power, heating, or lighting to 3 percent of the circuit voltage.

How much voltage drop is acceptable

The acceptable voltage drop is typically within 5%, but it can vary based on electrical system requirements, load conditions, cable types, length, and national/regional electrical standards.