Can I use a AC 250V 1A rocker switch for a 5V 4A DC project?

Thread Starter

Bassquake

Joined Feb 16, 2018
46
As title really.

Wondering if ok to use a rocker switch that specifies AC 250V 1A for a 5V 4A power supply plug? It's for a usb hub.
 

OBW0549

Joined Mar 2, 2015
3,566
I wouldn't do it. Aside from the issue of severely overloading the contacts with 4X their rated current, there's the issue of contact resistance and voltage drop: running on only 5 volts, your application is likely going to be VERY sensitive to any voltage drop across the contacts-- and that voltage drop is likely to be very substantial due to the high current.

Buy a proper switch meant for low-voltage, high-current service.

And don't get it from Ebay.
 

Thread Starter

Bassquake

Joined Feb 16, 2018
46
I wouldn't do it. Aside from the issue of severely overloading the contacts with 4X their rated current, there's the issue of contact resistance and voltage drop: running on only 5 volts, your application is likely going to be VERY sensitive to any voltage drop across the contacts-- and that voltage drop is likely to be very substantial due to the high current.

Buy a proper switch meant for low-voltage, high-current service.

And don't get it from Ebay.
Ok will do. Any in particular you recommend?
 

dl324

Joined Mar 30, 2015
12,792
Wondering if ok to use a rocker switch that specifies AC 250V 1A for a 5V 4A power supply plug?
You need to consult the datasheet.

I looked at a datasheet for D4 Cherry switches. They only gave a DC rating for the last one:
clipimage.jpg
And the DC current capability was lower.

This is from C&K:
clipimage.jpg
 

MisterBill2

Joined Jan 23, 2018
8,448
What is not mentioned is if the switch is in the mains power to that 5 volt supply, or if you are wanting to switch the 5 volts line. There is a very big difference. It should be OK switching the mains power, not the 5 volts line.
 

Thread Starter

Bassquake

Joined Feb 16, 2018
46
What is not mentioned is if the switch is in the mains power to that 5 volt supply, or if you are wanting to switch the 5 volts line. There is a very big difference. It should be OK switching the mains power, not the 5 volts line.
It was for the 5v line. Have selected a 6A inline rocker switch now. Thanks all.
 

MisterBill2

Joined Jan 23, 2018
8,448
It is quite unusual to switch the DC power line for a hub. Why do it? That is a puzzle to me. Generally the hub stays on with the computer serving it.
 

Thread Starter

Bassquake

Joined Feb 16, 2018
46
I put a switch on the hubs psu as it was drawing 2 watts even without anything plugged in to the usb ports, compared to 0.1 watts when PSUs switch is off so it's to save electricity (I'm on a meter)!

The hub uses the pc for low power stuff like flash drives or ssds. If I need to plug in a mechanical drive, I can just flip switch to provide more power.
 
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