HOW-TO GUIDE
Why Does My LED Power Supply Keep Shutting Off? How to Troubleshoot It
By the OhmSavvy Research Team ·
Let a hot driver cool before touching it
- Allow a driver that's shut down from overheating to cool before handling it.
- Disconnect power before inspecting or reconnecting any LED strip sections.
- Don't exceed the driver's rated wattage even temporarily to "test" whether it holds.
1Check your LED load's total wattage
Add up the rated wattage of every strip or fixture connected to the driver, including anything added since the system last worked reliably, and compare the total against the driver's maximum rated output. A load at or beyond that limit is one of the most common, simplest causes of repeated shutdowns.
2Measure output voltage right at shutdown
With the meter connected across the driver's DC output and the system running, watch the voltage as the shutdown occurs (or immediately check it right after). Output voltage dropping to 0 V at the moment of shutdown is the expected behavior of a driver's protection circuit doing its job.
| Pattern observed | Likely cause |
|---|---|
| Shuts off quickly, cools, then works again briefly | Thermal protection — check ventilation and ambient temperature |
| Shuts off the moment load is applied | Overload or a short somewhere in the connected LEDs |
| Shuts off randomly with no clear pattern | Possible internal driver fault — consider a replacement |
| Output voltage never recovers after shutdown | Driver has failed outright, not just tripped a protection feature |
The wattage check from step 1 is simple arithmetic, so work it on paper first. Take an illustrative 16.4 ft (5 m) reel of 12 V strip rated at 14.4 W per meter: 5 × 14.4 = 72 W. On a 60 W driver that load is 120% of capacity, which is exactly the situation that produces the top trace. A widely used rule of thumb is to keep the load at or below about 80% of the driver's rating for headroom and cooler running, so this strip wants a driver of at least 72 ÷ 0.8 = 90 W. Use the per-foot or per-meter figure printed on your own strip's spec sheet rather than these example values.
3Check for overheating
Check the driver's installation location for adequate ventilation, and confirm any built-in cooling fan is actually spinning and unobstructed. Many drivers include thermal shutdown specifically to protect themselves, so a pattern of shutting off after running a while, then working again once cooled, strongly suggests heat as the trigger.
Disconnect sections to isolate a shorted strip
4Check for a short in the LED circuit
With the driver off and unplugged, check resistance across the output terminals with the LED load still connected. A reading at or near 0 Ω (rather than the higher resistance expected through working LEDs) suggests a short somewhere in the connected strip or fixture wiring.
Which meter to use
A meter with DC volts and resistance ranges covers this whole test. See the full best multimeters roundup.
Meters in our reviews
DC volts and resistance for driver and LED-circuit diagnosis.
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Frequently asked questions
How do I know if I'm overloading the driver?
Add up the rated wattage of every LED strip or fixture connected to the driver and compare the total against the driver's maximum rated output wattage, printed on its label. Running right at or above that limit is a common and simple cause of repeated shutdowns, especially after adding more LEDs to an existing run.
Why would a driver work fine for a while, then start shutting off?
Thermal protection is a common cause: a driver installed in a poorly ventilated space can run fine when the surrounding temperature is cool, then start tripping its thermal protection once ambient temperature rises (seasonally, or simply after running for a longer stretch). Check the installation location's ventilation if shutdowns correlate with heat.
Could a short in the LED strip itself cause the driver to shut down?
Yes — a damaged LED strip with a short somewhere along its length can trip a driver's short-circuit or overcurrent protection, shutting it down even though the driver itself is healthy. Disconnect sections of the LED run and reconnect them one at a time to isolate a shorted section.
Does cutting an LED strip at the wrong point cause this kind of problem?
Yes, if cut somewhere other than the marked cut points (usually indicated by a line and scissor icon on the strip), you can create a short or an open circuit at that exact spot. Inspect any recently cut ends closely if the problem started after modifying the strip length.
My driver has a cooling fan — could that be the actual problem?
Yes — a failed or clogged cooling fan on a driver that relies on active cooling can cause it to overheat and shut down even under a normal load it would otherwise handle fine. Check that any fan is spinning freely and that vents aren't blocked by dust.
