[GreenKeys] Telco Color Codes

[Don Robert House]

>Has anyone ever seen a 48VDC color code that labels the positive as
>BLACK and the negative as RED?  I seem to recall that RED is always
>positive.
>
>Jack WA2HWJ

Jack,

Black is GROUND or RETURN

Red is BATTERY

In the case of telecommunications systems Ground is always Positive. 
Battery is always Negative.
The reason for this is to keep the copper pairs from "de-plating" due 
to electrolysis.  In smaller gauges the positive ground wire is 
alternating RED / BLACK and the negative battery is solid RED.

Don
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Don R. House
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