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Remote Head Voltage Drop Instruction

12V vs 24V for Remote Heads: Distance, Voltage Drop & Wire Size

When should you choose 12V or 24V for remote heads? This guide explains how voltage choice affects run length, voltage drop, and wire size—with practical rules, example layouts, and an inspection checklist.

Last updated: October 2025

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Why voltage matters (and how drop shows up)

Lower-voltage systems are more sensitive to resistance in long runs and small conductors. As runs get longer or current increases (more heads, higher-watt heads), the voltage at the last head can sag—causing dim or unstable output.

Basic idea: Vdrop ≈ 2 × L × I × Rwire (use round-trip length)

Keep drop within your design limit (commonly ~5%). If drop is high → shorten runs, step up conductor gauge, reduce head count per run, or consider 24V.

Choosing 12V or 24V (rules of thumb)

  • 12V — Shorter runs, few heads, interior paths, compact rooms. Easier to integrate with small remote-capable units.
  • 24V — Longer runs, exterior canopies/corridors, higher total load, or where you want smaller-gauge conductors for the same distance.
  • Confirm distances: Check the wire gauge & distance tables for one-way max distances at a ~5% drop target.

Wire-size method (quick, repeatable)

  1. List each run’s heads and wattage per head to get total load (W).
  2. Convert load to current at your chosen supply voltage.
  3. Estimate length (panel → far head → back). Use round-trip for drop.
  4. Pick an initial AWG from the distance tables.
  5. Iterate: if drop exceeds target, go up a gauge or split the run.

Layout & topology (it’s not just the math)

  • Star (home-run) topology: Best for long runs and precise control of drop; fewer cumulative losses per head.
  • Short daisies: Acceptable for low-watt heads on very short paths; keep head count per chain small.
  • Aiming & spacing: Good optics reduce how many heads you need. See the remote head spacing guide and, outside, IP65 spacing & aiming.
  • Compatibility: Match head voltage to the remote-capable unit and confirm families with a compatibility matrix.

Examples (conceptual)

Example A – Exterior canopy, long run: Multiple heads along a covered walkway. Start at 24V, home-run segments, and select AWG using the tables. Aim beams to overlap slightly between fixtures.

Example B – Small interior corridor: Two to three compact heads near doors and turns. 12V is often sufficient with short home-runs and a moderate AWG. Confirm spacing with the spacing guide.

Inspection-ready checklist

  • Voltage choice documented: 12V or 24V rationale + expected distances and load.
  • Wiring math on file: Current, round-trip length, AWG, and drop target.
  • Coverage: Door thresholds, landings, and first section of path are evenly lit; verify aiming on site. If outdoors, apply IP65 spacing & aiming.
  • Compliance docs: Keep spec sheets and test logs; see the code requirements overview for what AHJs expect.

This article focuses on the voltage choice (12V vs 24V) and its impact on conductor size and distance. For fundamentals and step-by-step sizing, use the core remote head sizing & wiring guide.