TOA Electronics EX-16 manual Cable Installation, Core Diameter Versus Transmission Distance

3.2 Cable Installation

Wire type, number of wire pairs and number of individual wires are to be determined for individual sections of the wiring system according to the guidelines set down below.

*4-wire twisted pair cables are to be used for wiring between indoor terminal boards, intermediate terminal boards, main terminal boards, etc.

*Outdoor wires should be used where wiring passes through inaccessible areas such as in ceilings or under floors. Indoor wires may also be used, however, in cases where there is no risk of deterioration due to exposure to heat, etc.

*The number of cable pairs laid should be determined considering the possibility of future expansion of the system.

*There is a limit to the diameter of cables that can be used to connect stations to the terminals of EX-16. This limit must be taken into con- sideration when planning the wiring of this system. The diameter should measure between 0.016" (0.41mm) and 0.031" (0.79mm).

3.3Core Diameter Versus Transmission Distance

The diameter of the cable to be used should be determined so that the set

limits for speech attenuation (3dB maximum for transmission from the

exchange to the station) and for the DC resistance (DC loop resistance: less

than 300 ohms) are met.

Speech Attenuation, DC Loop Resistance and Service

Distance as Functions of Core Diameter

		Speech	DC Loop	Service
AWG no.	Core	Attenuation	Resistance	Distance
	Diameter	dB per 1000 ft.	per 1000 ft.	ft.
(solid)
	mils. (mm)	(dB per 1 km)	per 1 km)	(km)
22	25.3	0.411	35.1	7,300
	(0.64)	(1.35)	(115)	(2.2)
24	20.1	0.521	54.5	5,500
	(0.51)	(1.71)	(179)	(1.1)

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