Author Topic: Kill switch recommendations and wiring  (Read 124 times)

synthpunk

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Re: Kill switch recommendations and wiring
« on: 08 May 22, 02:28 pm »
Most big toggle switches have a hefty AC current rating, but can skimp on their DC current rating.

If the switch is interrupting a DC line with a reasonable amount of power flowing through it, then the contacts will arc. All switches will do it. If you do it enough times then the contacts within the switch will build up extra carbon and probably flash over.

Switching an AC line makes much smaller sparks, as there’s a reasonable chance the switch will break at a zero crossing as the AC goes through 0 volts 50 times a second, so the sparks are much much smaller. So the switch can switch a higher rated AC current. In most electronics, it makes more sense to switch the ac side of a power supply than the DC side, as the switches are much cheaper.

I don’t think cyclekart electrics will have an ac side, it’s DC or nothing.

So in this application, look for a switch that can handle a large DC current. It will be much more expensive than a normal (AC) switch, due to being built much more robustly.

That’s probably a fairly shonky explanation but hopefully it might make things a bit clearer as to why some switches might fail. A switch that has a 6Amp rating at 250 AC volts  might well fail in a DC setting, as it might only be rated for 0.5 amps DC…