Categories: Heating materials , Resistance materials
Standard tolerances for wire and ribbon are given below. Size tolerances do not apply to material manufactured to resistance tolerances and vice-versa.

Tolerances on electrical resistance

RESISTANCE OF WIRE AT 20°C (68°F)

Diameter ≤ 0.127 mm (0.005 in) ± 8%.

All dimensions > 0.127 mm (0.005 in) ± 5%.

RESISTANCE OF RIBBON

For cold rolled strips and ribbon, all widths and thickness’ ± 5%.

TOLERANCES ON DIMENSIONS

Tolerances on diameter of wire according to the EN 10 218-2 T4 standard

Wire size Max deviation from nominal value Max ovality
mm in mm in
d Tol = ± 0.015·√d Tol = ± 0.002976·√d Tol ≤ 0.015·√d Tol ≤ 0.002976·√d

Caption=Max ovalitya – b

TOLERANCES ON DIMENSIONS OF COLD ROLLED RIBBON

Ribbon is normally specified with a resistance tolerance. If requested, dimension tolerance on width can be applied as below.

Width, mm (in) Thickness, mm (in)
0.07 – 0.2 0.2 – 0.5 0.5 – 0.8
(0.0028 – 0.008) (0.008 – 0.020) (0.020 – 0.031)
0.5 – 1.5 +0.02 – 0.04 +0.01 – 0.03
(0.020 – 0.059) (+0.0008 – 0.0016) (+0.0004 – 0.0012)
1.5 – 2.5 +0.04 – 0.07 +0.03 – 0.04 +0.02 – 0.04
(0.059 – 0.098) (+0.0016 – 0.0028) (+0.0012 – 0.0016) (+0.0008 – 0.0016)
2.5 – 4.0 ±0.08 +0.12
(0.098 – 0.157) (±0.0031) (+0.0047)