Resistance Wire
Resistance wire is used to control the amount of current in a circuit. High resistivity is better since a shorter wire can then be used. When the stability of the resistor is of primary importance the alloy’s temperature coefficient of resistivity and corrosion resistance are very important in material selection. When it is used for heating elements for applications such as electric heaters and toasters, high resistivity and oxidation resistance is important.
Sometimes resistance wire is insulated by ceramic powder and sheathed in a tube of another alloy. Such heating elements are used in electric ovens and water heaters, and in specialized forms for cooktops.
Nichrome, a non-magnetic 80/20 alloy of nickel and chromium, is the most common resistance wire for heating purposes because it has a high resistivity and resistance to oxidation at high temperatures. When used as a heating element, it is usually wound into coils. One challenge when using nichrome wire is that common tin-based electrical solder will not bond with it, so the connections to the electrical power must be made using other methods such as crimp connectors or screw terminals.
If you have any questions or comments, please contact us.
Calculator tool
Enter the resistivity value (OHMS/CMF) of any alloy from the chart below into the RESISTIVITY cell (double click the cell to highlight/clear/input your selection). Enter the desired diameter of the wire into the DIAMETER cell and the calculator will give minimum and maximum resistance values for standard 5% range, and special order 3% range. All values are for 20C.
Properties of Major Alloys
| Material | Chemical Composition (%) | Resistivity at 20°C | Coefficient of Linear Expansion Between 20-100°C | Tensile Strength (PSI at 20C) | Specific Gravity | Pounds Per Cubic Inch | Magnetic Attraction | Approx. Melting Point (°C) | ||
|---|---|---|---|---|---|---|---|---|---|---|
| OHMS/ CMF | TCR 0-100°C | Min. | Max. | |||||||
| MWS-875 | 22.5 Cr, 5.5 AI, .5 Si, .1 C, bal. Fe | 875 | .00002 | .000012 | 105,000 | 175,000 | 7.10 | .256 | Strong | 1520 |
| MWS-800 | 75 Ni, 20 Cr, 2.5 AI, 2.5 Cu | 800 | .00002 | .000014 | 100,000 | 200,000 | 8.10 | .293 | None | 1350 |
| MWS-675 | 61 Ni, 15 Cr, bal. Fe | 675 | .00013 | .0000137 | 95,000 | 175,000 | 8.247 | .2979 | Faint | 1350 |
| MWS-650 | 80 Ni, 20 Cr | 650 | .00010 | .0000132 | 100,000 | 200,000 | 8.412 | .3039 | None | 1400 |
| ALLOY 42 | 42 Ni, bal. Fe | 390 | .0010 | .0000029 | 70,000 | 150,000 | 8.10 | .295 | Strong | 1425 |
| MWS-294 | 55 Cu, 45 Ni | 294 | .00002* | .0000149 | 60,000 | 135,000 | 8.90 | .321 | None | 1210 |
| MWS-294R | 29 Ni, 17 Co, bal. Fe | 294 | .0033 | .0000033 | 65,000 | 150,000 | 8.36 | .302 | Strong | 1450 |
| Manganin | 13 Mn, 4 Ni, bal. Cu | 290 | .000015** | .0000187 | 40,000 | 90,000 | 8.192 | .296 | None | 1020 |
| Alloy 52 | 50.5 Ni, bal. Fe | 260 | .0029 | .0000049 | 70,000 | 150,000 | 8.25 | .301 | Strong | 1425 |
| MWS-180 | 23 Ni., bal. Cu | 180 | .00018 | .0000159 | 50,000 | 100,000 | 8.90 | .321 | None | 1100 |
| MWS-120 | 70 Ni, 30 Fe | 120 | .0045 | .000015 | 70,000 | 150,000 | 8.46 | .305 | Strong | 1425 |
| MWS-90 | 12 Ni, bal. Cu | 90 | .0004 | .0000161 | 35,000 | 75,000 | 8.90 | .321 | None | 1100 |
| MWS-60 | 6 Ni, bal. Cu | 60 | .0005 | .0000163 | 35,000 | 70,000 | 8.90 | .321 | None | 1100 |
| MWS-30 | 2 Ni, bal. Cu | 30 | .0013 | .0000165 | 30,000 | 60,000 | 8.90 | .321 | None | 1100 |
| Nickel 205 | 99 Ni | 57 | .0048 | .000013 | 60,000 | 135,000 | 8.90 | .321 | Strong | 1450 |
| Nickel 270 | 99.97 Ni | 45 | .0067 | .000013 | 48,000 | 95,000 | 8.89 | .321 | Strong | 1452 |
*TCR at 25-105°
**TCR at 15-35°C
Note: Available bare or insulated. See the insulation guide.
Resistance Alloy Data
Resistivity of some common materials
| Material | Resistivity (OHM-CMIL/FT) | Resistivity (10−6 OHM-CM) |
|---|---|---|
| Aluminum | 15.94 | 2.650 |
| Brass | 42.1 | 7.0 |
| Carbon (amorphous) | 23 | 3.95 |
| Constantan | 272.97 | 45.38 |
| Copper | 10.09 | 1.678 |
| Iron | 57.81 | 9.61 |
| Manganin | 290 | 48.21 |
| Molybdenum | 32.12 | 5.34 |
| Nichrome | 675 | 112.2 |
| Nichrome V | 650 | 108.1 |
| Nickel | 41.69 | 6.93 |
| Platinum | 63.16 | 10.5 |
| Stainless Steel (304) | 541 | 90 |
| Steel (.5% carbon) | 100 | 16.62 |
| Zinc | 35.49 | 5.90 |
Common Alloy Trade Names
| MWS Wire | Carpenter Tech. | Driver-Harris | Harrison | Hoskins | Jelliff | Kanthal | Molecu |
|---|---|---|---|---|---|---|---|
| MWS - 875 | Alchrome 875 | - | HAI-FeCr Al25 | Alloy 875 | - | Kanthal A-1 | - |
| MWS - 800 | Evanohm | Karma | HAI-431 | Chromel R | Alloy 800 | Nikrothal L | Moleculoy |
| MWS - 675 | Tophet C | Nichrome | HAI-NiCr 60 | Chromel C | Alloy C | Nikrothal 6 | Electroloy |
| MWS - 650 | Tophet A | Nichrome V | HAI-NiCr 80 | Chromel A | Alloy A | Nikrothal 8 | Protoly |
| MWS - 294 | Cupron | Advance | HAI-CuNi 102 | Copel | Alloy 45 | Cuprothal 294 | Neutroloy |
| MWS - 294R | Kovar | - | HAI-373 | - | - | - | - |
| MWS - 180 | 180 Alloy | Midohm | HAI-180 | Alloy 380 | Alloy 180 | Cuprothal 180 | - |
| MWS - 120 | Balco | Hytemo | HAI-380 | - | Alloy 120 | - | Pelcoloy |
| MWS - 90 | 90 Alloy | #95 Alloy | HAI-90 | Alloy 290 | Alloy 90 | Cuprothal 90 | - |
| MWS - 60 | 60 Alloy | Lohm | HAI-60 | Alloy 260 | Alloy 60 | Cuprothal 60 | - |
| MWS - 30 | 30 Alloy | #30 Alloy | HAI-30 | Alloy 230 | Alloy 30 | Cuprothal 30 | - |