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Bt Connections / Telephone Extension / Phone Fault Bt Info
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<blockquote data-quote="PBC_1966" data-source="post: 96185" data-attributes="member: 7302"><p>Some conversions to 431/631 jacks were wired that way, but you'll also find green &amp; brown the opposite way round.</p><p></p><p>In the GPO days, blue &amp; orange from the incoming line were B &amp; A respectively, with green being used for local earth where required for party line operation or PBX recall. Hence green was often used on 4 for local earth to PBX extensions with the new jacks, and brown for the bell feed/shunt on 3 for domestic extensions.</p><p></p><p>These days, many people are totally unfamiliar with the older color code, so it's not unusual to find the wiring completely mixed up from the old standard where somebody has tried to add an extension in more recent times.</p><p></p><p>Larger sizes can also be found in some domestic properties. 4-pair is not that unusual:</p><p></p><p>Pair 1 - Orange / White</p><p></p><p>Pair 2 - Red / Slate</p><p></p><p>Pair 3 - Blue / Brown</p><p></p><p>Pair 4 - Green / Black</p><p></p><p>The line current will depend upon the resistance of the loop, which is largely dependent upon distance from the exchange. On long loops, you may see a considerably lower current, down to about 25mA.</p><p></p><p>On the 48V vs. 50V issue, these are the nominal voltages which are specified on opposite sides of the Atlantic. In North America the nominal battery voltage is always shown as 48V, but in the U.K. it's always been 50V.</p></blockquote><p></p>
[QUOTE="PBC_1966, post: 96185, member: 7302"] Some conversions to 431/631 jacks were wired that way, but you'll also find green & brown the opposite way round. In the GPO days, blue & orange from the incoming line were B & A respectively, with green being used for local earth where required for party line operation or PBX recall. Hence green was often used on 4 for local earth to PBX extensions with the new jacks, and brown for the bell feed/shunt on 3 for domestic extensions. These days, many people are totally unfamiliar with the older color code, so it's not unusual to find the wiring completely mixed up from the old standard where somebody has tried to add an extension in more recent times. Larger sizes can also be found in some domestic properties. 4-pair is not that unusual: Pair 1 - Orange / White Pair 2 - Red / Slate Pair 3 - Blue / Brown Pair 4 - Green / Black The line current will depend upon the resistance of the loop, which is largely dependent upon distance from the exchange. On long loops, you may see a considerably lower current, down to about 25mA. On the 48V vs. 50V issue, these are the nominal voltages which are specified on opposite sides of the Atlantic. In North America the nominal battery voltage is always shown as 48V, but in the U.K. it's always been 50V. [/QUOTE]
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