When is a circuit breaker required in a circuit?

[2DPrinter]

So i am doing a homemade ebike with a razor motor, 24v batteries, and a throttle and controller. Would this need a circuit breaker?

[mariushm]

Well, you would have to look requirements for having a street legal electric bike or whatever that would classify as.

 

Some kind of fast battery disconnect would be a good idea, just in case for example you crash the bike and you don't want a short to burn your bike... or to disconnect the battery in case firemen throw water on the bike shorting wires which could overheat and burn with flames, doing more damage.

[Kilrah]

You want a fuse/breaker anytime an overload or short would lead to catastrophic results...

[Hackentosher]

For that application, I would strongly recommend a fuse because they're dead nuts reliable and I believe they can be faster than breakers. The size of the circuit interrupter depends on the lowest maximum continuous current consumption of any one device in the power system. For example, if your battery can safely deliver 100 A but your motor controller can only consume 40 A, then I would put a 40 A fuse between the battery and motor controller.

[2DPrinter]

On 1/30/2022 at 4:17 PM, Hackentosher said:

For that application, I would strongly recommend a fuse because they're dead nuts reliable and I believe they can be faster than breakers. The size of the circuit interrupter depends on the lowest maximum continuous current consumption of any one device in the power system. For example, if your battery can safely deliver 100 A but your motor controller can only consume 40 A, then I would put a 40 A fuse between the battery and motor controller.

thank you this is very helpful!