General Question About Switches

[vne147]

If a switch's data sheet says it's rated for 2A at 250V, can I assume that it is safe to push 4A at 125V through it, and 8A at 62.5V, and so on?

I am trying to pick a 3PDT switch for a project. If found one that is the right physical size but the data sheet says it's only rated for 2A at 250V. I will need it to carry between 3 - 4 A at 6V. Should I find another switch or should this one work?

Thanks.

 

[smanches]

No. Those are both separate ratings. It can take up to 2A and take up to 250V. It's not a power rating, so you can't convert it to power first.

 

[crutschow]

Your assumption is not correct. The switch rating is the maximum voltage and current it can handle, it's not a power rating. You can not increase the current at a lower voltage. If you want 4A at 6V then you need a 4A switch.

 

[vne147]

Thanks for the quick responses. It didn't really make sense to me for it to be a power rating but I saw one data sheet that said:

Rating: 2A/250VAC; 5A/120VAC or 28VDC

I wasn't sure how to interpret the two different current ratings there.

 

[crutschow]

Thanks for the quick responses. It didn't really make sense to me for it to be a power rating but I saw one data sheet that said:

Rating: 2A/250VAC; 5A/120VAC or 28VDC

I wasn't sure how to interpret the two different current ratings there.

In that case they are rating a higher current at a lower voltage since the rating is based, in part, on the arc damage to the contacts that occurs when the switch is opened under load. You can break a higher current at a lower voltage. But for this switch you would never want to break more than 5A, no matter how low the voltage.

 

[vne147]

In that case they are rating a higher current at a lower voltage since the rating is based, in part, on the arc damage to the contacts that occurs when the switch is opened under load. You can break a higher current at a lower voltage. But for this switch you would never want to break more than 5A, no matter how low the voltage.

Ahhh, OK that makes sense. Thanks. I'm glad I asked.