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amps, volts and mains switches

Posted by UkIan

UkIan

amps, volts and mains switches
October 28, 2014 07:21PM

Registered: 9 years ago
Posts: 376

I'm sure I should know this, but it turns out I don't. I'm looking online for a new switch to fit in the mains cable of my printer power supply. I use the nice LED lighting ones.

I vaguely remember how power supplies work, but I can't remember the maths. If my printer is using 30A at 12V, what rating mains switch do I need? Mains voltage here in the UK is 230V, so what amps should it support?

Thanks

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UkIan

Re: amps, volts and mains switches
October 29, 2014 02:02AM

Registered: 9 years ago
Posts: 376

Convert to watts and back again. Does that work?

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Traumflug

Re: amps, volts and mains switches
October 29, 2014 06:05AM

Registered: 13 years ago
Posts: 7,616

Unless you have an industrial connection to the power grid, your connection maxes out at 16 amps anyways and most mains switches allow these 16 A.

That said, 12 V * 30 A / 0.8 (PSU efficiency) = 450 watts. 450 W / 220 V = 2.05 A.

Generation 7 Electronics	Teacup Firmware	RepRap DIY

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UkIan

Re: amps, volts and mains switches
October 29, 2014 06:41AM

Registered: 9 years ago
Posts: 376

I'm documenting the whole heated bed build. It's a but like robert's bed but built by an idiot, so I'm trying to ensure the last picture isn't of the house on fire smiling smiley