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Distribution Systems: Secondaries

Secondaries
Secondaries are the conductors originating at the low-voltage secondary winding of a distribution transformer. Secondaries for residential service are three-wire single-phase circuits. They extend along the rear lot lines, alleys, or streets past customer's premises. The secondaries can be overhead lines or underground lines. 

Overhead secondary lines are usually strung below the primary lines and typically in a vertical plane. When secondaries are strung in a vertical plane, they are directly attached to the support pole one above the other. This is in contrast to the primary lines which are often strung on a cross bar or other attachment in a horizontal or "V" shaped plane.


Figure 1. Cabled secondaries
Figure 1. Cabled secondaries
 
Figure 2. Secondaries in a vertical plane
Figure 2. Secondaries in a vertical plane
Figure 3. Cabled secondaries, primaries in a "V" plane
Figure 3. Cabled secondaries, primaries in a "V" plane

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