Planning Rack Power: C13, C19 and PDU Cord Strategy
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Network cables get patch panels, color schemes and Velcro; power cords get whatever was in the box, in whatever length it came. Then someone unplugs the wrong server. Rack power deserves ten minutes of planning, and this is that ten minutes.
1. Count your inlets
Walk the rack and tally connector types: the small trapezoid inlets are C14 (they take C13 cords — servers, switches, most gear); the larger rectangles are C20 (they take C19 cords — big PSUs, UPS units, some PDUs). One cord per power supply, and dual-PSU machines get two. The naming logic is in our power cord decoder.
2. Feed from the PDU, not the wall
Inside a rack, equipment plugs into PDUs with C14-to-C13 jumper cords — IEC on both ends, happy at 100–250V worldwide. The wall (or UPS) side uses NEMA cords sized to the load: 14AWG for anything approaching 15A.
3. Color-code the A/B feeds
Redundant power only helps if you can see it. Run every A-feed jumper in one color and every B-feed in another — our jumpers come in black, blue, green and red precisely for this. During maintenance, "pull every blue cord" is an instruction anyone can execute safely at 2 a.m.
4. Length and load discipline
Use the shortest jumper that reaches with a service loop — excess power cable is heat-trapping clutter that blocks airflow. On load: add up nameplate draw per PDU and keep steady-state usage around 80% of the circuit rating; that headroom absorbs power-on spikes. Gauge rule of thumb: 18AWG to 10A, 16AWG to 13A, 14AWG for 15A — when near a boundary, go thicker.
Fitting out a rack? Send the equipment list — we'll return a cord count by type, gauge and color in one pass.