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 (≈0.5–2 W each), especially in tight corridors, small rooms, or decorative installs where discreet form factor matters. If you expect longer home runs, multiple landings, or many heads on one circuit, compare options in 12V vs 24V for remote heads before committing.
How to budget load (plain-English math)
Manufacturers list a unit’s remote capacity in watts (W) at 90 minutes. Your plan passes the math test if you keep the total head load within the host’s listed capacity—with margin for temperature and aging.
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
Design buffer: target +20–30% headroom for ambient, battery aging, and future adds.
Typical per-head ranges: 0.5–2 W for compact LED heads; 3–5 W for higher-output MR-style heads. Always use the cut-sheet value for your model.
Wire gauge & distance (3.6V sensitivity)
At 3.6 V, small drops matter. Keep runs short, minimize splices, and size conductors so end-of-line heads stay bright at the end of the 90-minute test. 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 + back). If drop pushes heads dim or unstable, step up the gauge (e.g., AWG 18 → AWG 16 → AWG 14), shorten runs, or increase system voltage on new designs.
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; avoid long chains that accumulate drop.
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Polarity discipline: Mark
+/–at the unit and each head; reversed polarity is a common cause of “dead” heads on new installs.
Example builds (worked scenarios)
Example A — short corridors: Three 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. Use star topology; AWG 16 is typical for short runs—confirm distances using the wire-gauge tables noted earlier.
Example B — one longer branch: Two higher-output heads at 2 W each on a long corridor → 4 W total (borderline on small units). Reduce run length (place host closer), upsize conductors, or consider stepping system voltage on a new design (see the 12 V vs 24 V article linked above).
Example C — mixed loads: One 2 W head + two 0.75 W heads → 3.5 W total. If the host lists 4 W remote capacity, you have ~0.5 W nominal headroom—tight. Either pick a higher-capacity host or reduce a head’s wattage if your photometrics allow.
Inspection-ready checklist
- Compatibility: Unit voltage and head voltage must match; if mixing brands, verify with the compatibility matrix.
- Light levels: Aim/space heads for uniformity—see the spacing guide for overlap logic.
- Wiring docs: Keep a one-line diagram, head schedule (W, qty), conductor gauge, run lengths, and your drop math in the job folder.
- Functional tests & logs: Monthly quick test + annual 90-minute; keep logs. See the UL 924/NFPA 101/NEC 700 overview for what AHJs expect.
Troubleshooting checklist
- Dim far head: Recalculate on round-trip length; upsize wire or shorten the run. Confirm terminal torque and clean terminations.
- Intermittent flicker at end-of-test: Margin too tight; reduce load, add a second host, or move to 12 V on future revisions.
- One head dead: Check polarity at head and host, confirm voltage at head under load, and verify the head’s rated watts/voltage.
- Glare complaints: Tilt a few degrees off the walk line; widen beam on low mounts or narrow on higher mounts to shift the hot spot.
FAQ
How many 3.6V heads can one unit support?
Divide the host’s remote watt budget by a head’s watt draw and keep 20–30% margin. Example: 4 W budget ÷ 1 W/head ≈ 4 heads (tight); better at 3 heads for buffer.
When should I step up from 3.6V?
When runs are long, head count is high, or the far head dims at end-of-test. Consider 12 V/24 V designs and re-select AWG accordingly.
Does daisy-chain wiring ever make sense at 3.6V?
Only for very short, low-load branches. Prefer star topology to isolate runs, balance voltage drop, and simplify troubleshooting.
This article focuses on 3.6 V remote head wiring and load planning. For broader fundamentals (terminology, system selection, and universal sizing steps), use the core remote-head sizing & wiring guide linked in the CTA above.