I'm building my own PCB to power 8 in-wall LED's for a stairwell. I'd like to protect the LED's with fuses, but I'm unclear on how the voltage on fuses work. My specs are as follows:

LEDs: 5V, 600mA, 3W LED (x 8)

LED Driver Output: +5V, 5.0A, 35W DC

I think I understand how the amperage works with the fuses, but I'm not sure if the fuses need to be 5v or if they can be higher.

I'm not an electrical engineer, so I don't know what I'm doing, but here's where I'm at:


I have two questions.

  1. Can I go with a higher voltage fuse such as this: https://www.amazon.com/dp/B00X772B3M/ref=cm_sw_r_sms_c_api_i_P9r3EbTMEDREB
  2. Is there anything I'm missing in my circuit?

I appreciate any advice anyone can give.

Regards, TY

  • 1
    \$\begingroup\$ the voltage rating on a fuse is how much voltage the fuse will hold back, when it is blown, before it starts to arc and provide no protection \$\endgroup\$ – jsotola Jun 12 '20 at 19:08
  • \$\begingroup\$ That's extremely helpful. Thank you! \$\endgroup\$ – travyo Jun 12 '20 at 19:11
  1. You can use a higher voltage rating fuse.

  2. The schematic needs improvement. PTC is too slow to protect LEDs from overcurrent. Using a PTC to limit LED current is not as straightforward as it might seem. You need to add series resistor to limit the current. You can use a "led resistor calculator" for the values. For example: http://www.ohmslawcalculator.com/led-resistor-calculator

In your circuit depending on exact components you are wasting around 20 % on the series resistors. Consider using a dedicated LED driver, that adjusts the current or use a higher voltage and have several LEDs in series, so that smaller percentage of voltage is left over the resistor.

  • 1
    \$\begingroup\$ Definetly linking the LEDs in serie or with two series, would be much better. If typical LED voltage is 5V (check this) then one serie on 40V will do the job. Or two series with, preferably two separate 20V supplies. If you can find a constant current supply which matches the serie voltage and power, then it's even better. \$\endgroup\$ – Fredled Jun 12 '20 at 23:00
  • \$\begingroup\$ Beware that the wires must be thick enough. \$\endgroup\$ – Fredled Jun 12 '20 at 23:01

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.