Customers often ask: what exactly is the difference between isolated and non-isolated drivers, and which one is better in terms of quality? This is a very common but easily misunderstood question.
It’s important to note that we can’t simply say whether isolated or non-isolated drivers are “better” in quality—because there’s no absolute superiority between the two. Instead, the right choice depends on the specific application and requirements.
Now let’s discuss the specific differences between isolated driver and non-isolated driver.
The core difference between isolated and non-isolated designs lies in whether electrical isolation exists between the high-voltage input (AC 220V) and the low-voltage output (DC low voltage). Isolated driver: After AC 220V enters, it is first rectified into high-voltage DC. Then, through a switching circuit and transformer, the high voltage is converted to low voltage. The transformer is key—it transfers energy via magnetic field coupling, achieving physical isolation between the input (primary) and output (secondary) circuits. Finally, the low-voltage AC is rectified into the DC required by the LED. This voltage is so low that even direct human contact poses no danger.
Non-isolated driver: After rectifying the AC power (AC 220V), the voltage is directly stepped down and stabilized through switching circuits and components such as inductors and capacitors before being supplied to the LED. Throughout this process, the high-voltage input and low-voltage output are directly connected within the circuit without any physical isolation layer. When powered on, touching the output terminals with bare hands poses an electric shock hazard.
The second major difference lies in their conversion efficiency. Due to the distinct voltage conversion methods between the input and output of isolated and non-isolated drivers, their conversion efficiencies also differ. Non-isolated drivers typically achieve 93%-96% conversion efficiency, while isolated drivers generally operate at 88%-92%. For lighting fixtures of the same wattage, differing conversion efficiencies result in varying amounts of light energy produced.
For example, a 200W lamp powered by a non-isolated power supply ultimately yields 192W of light energy (200W × 96% conversion efficiency = 192W), achieving relatively higher luminous efficacy. The same 200W lamp using an isolated power supply yields 184W of light energy, 8W less than the non-isolated configuration. Since we utilize the light energy from the fixture, not the electrical energy, higher light output from the same electrical consumption indicates greater energy efficiency. Therefore, non-isolated drivers are generally preferred for lighting with higher lumen efficiency. Additionally, for this 200W luminaire, the isolated power supply consumes 16W of power, while the non-isolated power supply consumes 8W. Consequently, the isolated power supply requires thermal management for 16W of power dissipation, whereas the non-isolated power supply requires thermal management for 8W. This explains why isolated power supplies are typically larger in size than their non-isolated counterparts.
The third difference lies in their safety. In terms of the driver alone, for an isolated power supply, the input is connected to 220V high-voltage AC, while the output can be touched by hand. Under the same conditions, for a non-isolated power supply, the output cannot be touched by hand due to the risk of electric shock. After we install the driver into the lighting fixture, the output wires are connected to the light source board. Under normal circumstances, the circuit of the light source board is not connected to the housing, so there is no risk of electric shock when touching the metal shell. However, if the insulation layer of the driver’s input wires breaks and conducts electricity, safety hazards may arise.
Additionally, some customers may misunderstand the surge resistance capabilities of isolated and non-isolated power supplies, assuming isolated power supplies offer superior surge protection. In reality, when lighting fixtures and large equipment are connected in parallel circuits, neither isolated nor non-isolated power supplies are suitable. The true distinction lies not in whether a power supply is isolated or non-isolated, but in whether it employs dual-stage PFC or single-stage PFC technology. Naturally, we also do not recommend connecting any lighting fixtures and large equipment circuits in parallel, as this can cause damage to the lighting fixtures.
Of course, the costs of the two are also different. The cost of isolated power supplies is significantly higher than that of non-isolated ones, because isolated power supplies include additional transformers and have a larger physical size.
There is no absolute superiority in quality between isolated and non-isolated designs. When used appropriately, their theoretical lifespan and reliability show no fundamental difference. The key factors determining performance are the quality grade of the components used, the quality of the circuit design, and the effectiveness of thermal management.
If any more difference, let’s discuss together.
