Specifications

Abbreviations used in this section:
American Wire Gauge .......	AWG	Nichrome Heater Wire .........	NC
Single Lead Wire .............	SL	Heavy Duty Lead Wire ........	HD
Duo-Twist™ Wire ............	DT	Manganin Wire .................	MW
Quad-Twist™ Wire ...........	QT	Copper Twisted ................	CT
Quad-Lead™ Wire ...........	QL	Nonmagnetic ....................	NM

Material Properties		Phosphor bronze	Copper	Nichrome	Manganin
Melting range		1223 K to 1323 K	1356 K	1673 K	1293 K
Coefficient of thermal expansion		1.78 × 10^-5	20 × 10^-6	—	19 × 10^-6
Chemical composition (nominal)		94.8 % copper, 5% tin, 0.2% phosphorus	—	80% nickel, 20% chromium	83% copper, 13% manganese, 4% nickel
Electrical resistivity (at 293 K)		11 µΩ•cm	1.7 µΩ•cm	120 µΩ•cm	48 µΩ•cm
Thermal conductivity (W/(m•K))	*0.1 K*	NA	9	NA	0.006
	*0.4 K*	NA	30	NA	0.02
	*1 K*	0.22	70	NA	0.06
	*4 K*	1.6	300	0.25	0.5
	*10 K*	4.6	700	0.7	2
	*20 K*	10	1100	2.6	3.3
	*80 K*	25	600	8	13
	*150 K*	34	410	9.5	16
	*300 K*	48	400	12	22

	AWG	Resistance (Ω/m)			Diameter (mm)	Fuse current air (A)	Fuse current vacuum (A)	Number of leads	Name	Insulated diameter (mm)	Insulation type	Insulation thermal rating (K)	Insulation breakdown voltage (VDC)
	AWG	4.2 K	77 K	305 K	Diameter (mm)	Fuse current air (A)	Fuse current vacuum (A)	Number of leads	Name	Insulated diameter (mm)	Insulation type	Insulation thermal rating (K)	Insulation breakdown voltage (VDC)
Phosphor bronze	32	3.34	3.45	4.02	0.203	4.2	3.1	1	SL-32	0.241	Polyimide	493	400
								2	DT-32	0.241	Polyimide
								4	QT-32	0.241	Polyimide
								4	QL-32	0.241	Polyimide
	36	8.56	8.83	10.3	0.127	2.6	1.4	1	SL-36	0.152	Formvar^®	368	250
								2	DT-36	0.152	Polyimide	493	400
								4	QT-36	0.152	Formvar^®	368	250
								4	QL-36	0.152	Polyimide	493	400
Nichrome	32	33.2	33.4	34	0.203	2.5	1.8	1	NC-32	0.241	Polyimide	493	400
Copper	30	0.003	0.04	0.32	0.254	10.2	8.8	1	HD-30	0.635	Teflon^®	473	250
Copper	34	0.0076	0.101	0.81	0.160	5.1	4.4	2	CT-34	0.254	Teflon^®	473	100
Manganin	30	8.64	9.13	9.69	0.254	4.6	4.3	1	MW-30	0.295	Heavy Formvar^®	378	400
	32	13.5	14.3	15.1	0.203	3.8	3.5	1	MW-32	0.241	Heavy Formvar^®		400
	36	34.6	36.5	38.8	0.127	2.6	2.5	1	MW-36	0.152	Heavy Formvar^®		250

Phosphor bronze wire

Phosphor bronze wires (QL, QT, DT and NM), are suitable for almost all cryogenic applications. The low magnetoresistance of these wires make them the ideal choice for magnetic field use.

Physical Properties

Melting range: 1223 K to 1323 K (950 °C to 1050 °C)

Coefficient of thermal expansion: 1.78 × 10^-5

Thermal conductivity: 48 W/(m • K) at 293 K

Electrical resistivity (annealed): 1.15 × 10^-7 Ω • m at 293 K

Specific heat: 376.4 J/(kg • K)

Stress relief temperature (1 h): 423 K to 498 K (150 °C to 225 °C)

Chemical composition: nominal 94.8% copper, 5% tin, 0.2% phosphorus

Insulation

Polyvinyl Formal (Formvar^®)
Magnet wire is insulated with vinyl acetal resin, as a smooth uniform film. Formvar^® has excellent mechanical properties such as abrasion resistance and flexibility. The film will stand excessive elongation without rupture. When stressed during winding, Formvar^® has a tendency to craze upon contact with solvents such as toluol, naphtha, and xylol, therefore, it should be given an annealing preheat prior to varnish application. Formvar^® can be removed mechanically during terminal preparation. Formvar^® is rated to 3525 VAC for 32 AWG, 2525 VAC for 36 AWG.

Polyimide (ML)
ML is a film coated insulation made with polyimide resin. It is a Class 220 thermal life insulation with exceptional resistance to chemical solvents and burnout. It will operate at temperatures in excess of 493 K (220 °C) for intermittent duty. ML is unaffected by prolonged exposure to varnish solvents and is compatible with virtually all systems. Polyimide insulation is rated to 3525 VAC for 32 AWG, 2525 VAC for 36 AWG.

Note: At Lake Shore, we strip both Formvar^® and Polyimide mechanically using an Eraser Rush Model RT-2 mechanical stripper.

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