Currently, almost all the LED fluorescent lamps power supply are built-in. The so-called built-in power supply can be placed inside the tube. The advantage is that it can directly replace the existing fluorescent tubes, without any changes to the original circuit. Therefore, the shape of built-in power is usually in strip for convenience to insult it to semi-circular lamps.www.ctledlights.com

 There are two built-in power supply, one is non-isolated (Figure 1), one is isolated (Figure 2). Figure 1. Non-isolated LED fluorescent non-isolated power supply is in the LED load and hava a direct connection with 220V, so there is risk of electric shock when touching the load. Aluminum plate isolation insulating layer between 220V and aluminum is usually not easy to pass CE and UL certification. Figure 2. Isolated LED fluorescent lamp power supply is isolated at the input and output with isolation transformer, the isolation transformer may be normal frequency or high frequency. But can also isolate the input and output to avoid risk of electric shock. It is easy to pass CE or UL certification.