FED-STD-228A
4.6 The resistance shall be measured and recorded, then converted to ohms per unit length. The
temperature, conductor length, and conductor size shall be measured and recorded.
5. Temperature correction.
5.1 When the measurement is made at any other than a reference temperature, the resistance may be
corrected for moderate temperature difference to what it would be at the reference temperature as
follows:
Resistance T =
Rt_______
1 + αT(t-T)
where:
RT=Resistance at reference temperature, T.
Rt=Resistance as measured at temperature, t.
ΑT=Known or given temperature coefficient of resistance of the specimen being measured at reference
temperature, T.
T=Reference temperature
t=Temperature at which measurement is made.
NOTE: The parameter αT, in the above equation, varies with conductivity and temperature.. For copper of
100 percent conductivity and a reference temperature of 20°C, its value 0.00393. Values at other
conductivities and temperatures will be found in NBD Handbook 100 of the National Bureau of Standards.
Table 2 lists temperature coefficients for the common electrical conductor materials.
6.0 Report.
6.1 The report shall include:
6.2 Specimen length.
6.3 Conductor size.
6.4 Resistance measured.
6.5 Test temperature.
6.6 Correction calculation (if applicable).
6.7 Method of measurement.
6.8 Calculation to appropriate unit length resistance.
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