A practical, math-first guide to wiring 3.6V remote heads: how to budget load in watts, pick the right wire gauge, and keep voltage drop under control—so your remote-capable system passes inspection without overbuilding.
Last updated: October 2025
Why 3.6V—when it makes sense
Many compact heads and legacy remote-capable units operate at 3.6 V DC. It’s a solid choice for short runs with a handful of low-watt heads (e.g., 0.5–2 W each). If you expect longer home runs or many heads on one circuit, compare options in 12V vs 24V for remote heads before you commit.
How to budget load (the plain-English math)
Manufacturers list a unit’s remote capacity in watts (W) at 90 minutes. Your plan passes the math test if:
Total remote head load (W) = number of heads × watts per head
Pass rule: Total remote head load (W) ≤ unit’s remote capacity (W) at 90 min
Tip: Add a 20–30% design buffer for temperature, aging, and future changes.
Typical per-head ranges: 0.5–2 W for compact LED heads; 3–5 W for higher-output MR-style heads. Always use the spec’d wattage from your cut sheet.
Wire gauge & distance (why 3.6V is sensitive)
At 3.6 V, small drops matter. Keep runs short, minimize splices, and size conductors to hold drop within your design limit (often ~5%). For ready-to-use math and one-way distance tables by AWG, see the wire gauge & distance tables.
Rule-of-thumb: Calculate voltage drop on the round-trip length (out and back). If drop pushes heads dim or unstable, step up the gauge (e.g., AWG 18 → AWG 16 → AWG 14) or shorten the run.
Wiring topologies (star vs. daisy-chain)
- Star (home-run) topology: Best for 3.6 V. Each head (or small cluster) gets a shorter, dedicated run from the unit—easier to balance load and control drop.
- Short daisy-chains: Acceptable for very low-watt heads on very short runs. Keep head count per chain small.
- Document polarity: Mark +/– at the unit and each head; mis-polarity is a common troubleshooting headache.
Example builds (conceptual)
Example A: (3) compact heads at 1 W each → 3 W total. With a unit that provides ≥4 W remote capacity at 90 min, you’re within spec with buffer. Star topology with AWG 16 for short runs is typical; confirm distances using the tables.
Example B: (2) higher-output heads at 2 W each on one long corridor. 4 W total—borderline on small units. Reduce run length (closer unit), upsize conductors, or consider stepping voltage (see 12V vs 24V).
Inspection-ready checklist
- Compatibility: Confirm unit voltage and head voltage match; if mixing families, verify with a spec sheet or a compatibility matrix.
- Light levels: Aim and space heads per layout guidance (corridors, stairs, open areas)—see the spacing guide.
- Wiring docs: Keep a one-line diagram, head schedule (W, qty), conductor gauge, run lengths, and your math in the job folder.
- Functional test & logs: Perform push-button tests and retain logs; verify labeling and signage meet UL 924/NFPA 101/NEC 700 requirements.
This article focuses on 3.6 V remote head wiring and load planning. For broader fundamentals (terminology, system selection, and universal sizing steps), see the core remote head sizing & wiring guide.