Low-voltage magnetic track systems (12V/24V DC) cannot run off mains power directly — every installation needs a driver (LED transformer) that converts AC mains to the DC voltage the track feeds on. In field failures of low-voltage track installations, the driver is the single most common point of failure: undersized, poor quality, sealed away without access, or mismatched to a dimmer. This guide shows you how to specify one correctly, whether you buy from us or from anyone else.
Rule 1 — Size the driver with headroom (the 80% rule)
Add up the rated wattage of every light head on the circuit, then choose a driver whose rated output is at least 25% higher:
Minimum driver capacity = total fixture wattage × 1.25 (equivalently: keep the actual load at or below 80% of the driver’s rated output)
Worked example: a jewelry cabinet with 12 heads at 2 W each draws 24 W. Minimum driver capacity = 24 × 1.25 = 30 W. A driver run continuously at 100% of its rating runs hot, and heat is what kills drivers early — the headroom is what buys you years of service life.
Rule 2 — Never mix voltages
- 12V heads require a 12V DC driver; 24V heads require a 24V DC driver. Mixing voltages on one track does not “dim” the lights — it destroys them.
- On longer track runs, prefer 24V: at the same wattage it draws half the current, which means less voltage drop and more consistent brightness from the first head to the last.
- If the far end of a long run looks dim, do not upsize the driver — add a second power feed point or split the run across two drivers instead.
Rule 3 — Plan the circuit, not just the driver
- As good engineering practice, keep one power feed to roughly 20 heads or fewer. Smaller circuits limit the blast radius when something fails and make future extensions easier.
- Feed the track from the end closest to the driver to shorten cable runs.
- Write down the head count and wattage per circuit on your installation drawings — the electrician on site should never have to guess.
Rule 4 — Match the dimming protocol before you order in bulk
Dimmable drivers come in different protocols (TRIAC/phase-cut, 0-10V, PWM, DALI). A driver that does not match the wall dimmer or control system produces flicker, audible buzz, or a dead dimming range. Whatever protocol your project uses, test one sample driver with the actual dimmer on site before committing to the full order.
Rule 5 — Place the driver where it can be serviced
- Mount the driver outside the display cabinet where possible — in a ventilated service space, cabinet base, or ceiling void with an access panel.
- Never seal a driver inside an enclosed cabinet with no airflow.
- Leave a service loop and label the driver with the circuits it feeds. When a driver is eventually replaced (all drivers have a finite life), this turns a half-day fault into a 10-minute swap.
Supplier checklist — what to require in writing
| Rated output (W) and output voltage | Must match your calculation from Rule 1 |
| Efficiency and power factor | Ask for the figures; quality drivers publish them |
| Protection features | Short-circuit, over-load and over-temperature protection |
| Certification for your destination | CE/RoHS for the EU, UL/ETL for North America — confirm per market before ordering |
| Dimming compatibility sheet | Which dimmer brands/models the driver is tested with |
| Sample burn-in | Run one sample for 24–48 hours under your real load before bulk shipment |
Frequently asked questions
Do magnetic track lights need a transformer or driver?
Yes. 12V/24V DC magnetic track systems are low-voltage and require a driver between mains power and the track. Mains must never be connected directly to the track.
Can one driver power two separate tracks?
Yes, if the combined wattage stays within 80% of the driver’s rating and the voltage drop over the total run is acceptable. For longer or separate runs, one driver per track is simpler to service and diagnose.
Why do my track lights flicker?
The usual causes, in order of likelihood: a dimmer incompatible with the driver, a driver running at or beyond its rating, poor contact between a head and the track conductor strips, or loose wiring at a connector. Isolate by testing one head directly at the power feed.
What happens if the driver is undersized?
Overloading shortens driver life dramatically — heat builds up, protection circuits trip intermittently (flicker or shutdown), and the driver eventually fails. It is the most common and most avoidable failure in low-voltage track installations.
What we can help with
Tell us the number of heads, their wattage, and your destination market, and our team will check the driver sizing for your layout and quote the matched driver together with the track and heads. See our magnetic track lighting system overview, the full configuration checklist for the rest of the BOM, or request a quote.