electrical specification on Cat 5 cable

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 Question by kevin cheung posted 30 Jun 2000
 electrical specification on Cat 5 cable
I would like to know if there is any standard on the electrical specificaion of the Cat 5 cables.
I am interested in knowing the resistances, inductance and characteristic impedance of Cat 5 cables.
 Answer by Roman Kitaev posted 19 Jul 2000
The ANSI/TIA/EIA-568A standard gives the following specs for electrical parameters for Cat5 horizontal 4-pair cables:

1) DC resistance
The resistance of any conductor shall not exceed 9.38 Ohm per 100 m (328 ft) at a temperature of 20 Celsius.

The resistance unbalance between two conductors of any pair shall not exceed 5% when measured at a temperature of 20 Celsius.

2) Mutual capacitance
The mutual capacitance of any pair at 1 kHz and measured at 20 C should not exceed 5.6 nF per 100 m (328 ft).
The capacitance unbalance to ground at 1 kHz of any pair shall not exceed 330 pF per 100 m (328 ft) at 20 C.

3) Characteristic impedance
Horizontal Cat5 UTP cable shall have char. impedance of 100 Ohm +- 15% from 1 MHz to 100 MHz.

Additionally, the standard provide requirements for:
1) Attenuation (up to 100 MHz)
2) Near-end Crosstalk (up to 100 MHz)
3) Structured Return Loss (SRL) (up to 100 MHz)
4) Propogation Delay

Best regards,
Roman Kitaev, RCDD

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