I just installed this doorbell and I was just wondering what the reason for the fuse is and if it is necessary when using DC 12v power supply? I have it directly connected to a 12v DC power supply at the moment.
Last edited:
Ezviz DB1 - connected to DC 12v. Reason for fuse if no chime?
- Thread starter tempipcamuser101
- Start date
Fuses aren't meant to protect the device and it matters not if it's AC or DC; they're in place so that a defective device or a overly-high current situation (like a short between the fuse and the device) cannot draw more current than the supply conductor can provide safely. Without a fuse to open and therefore limit the current the conductor or the defective device could overheat and cause a fire.
Granted a doorbell circuit will likely not supply enough current to burn something up but I wanted to insure there is no misunderstanding on your part when and why fuses are needed. Many newer small power supplies and transformers are internally current-limited...it should state so on its label if it is.
It's true that 12 VDC won't hurt you if you grab it with your bare hands because the voltage is not high enough to make it through the high resistance of your skin in order to draw sufficient current to shock (Ohm's law, I = E/R, 4 milli-amperes is dangerous) . However, if the source can supply enough current and the conductors can carry it then you can practically arc-weld with 12 VDC. Ever seen a car battery set a car on fire?
Granted a doorbell circuit will likely not supply enough current to burn something up but I wanted to insure there is no misunderstanding on your part when and why fuses are needed. Many newer small power supplies and transformers are internally current-limited...it should state so on its label if it is.
It's true that 12 VDC won't hurt you if you grab it with your bare hands because the voltage is not high enough to make it through the high resistance of your skin in order to draw sufficient current to shock (Ohm's law, I = E/R, 4 milli-amperes is dangerous) . However, if the source can supply enough current and the conductors can carry it then you can practically arc-weld with 12 VDC. Ever seen a car battery set a car on fire?
Last edited:
This is kinda what I figured - as I understand the purpose of a fuse to be just that - as a fail safe.
Why is it not installed if you use a chime however? Is there a fuse further down the line?
Either as I said in the 2nd paragraph above (internally current-limited) OR..
In some cases a fuse or circuit breaker may supply the transformer primary; too much secondary current (the output of the transformer) will also cause that fuse or breaker to open.
