I am using the TinkerKit Relay Module and recently they changed the relay mounted on the board from a white one with 10A250V~ to a black one with 10A125V~.

In my country the voltage is 220V~. Can I use the black relay in my application, safely? May be there problems that I have to be careful?

  • 2
    Definitely no!!!
    – Gerben
    Mar 16 '15 at 14:06
  • 1
    Though it will most likely work, safely is wrong. If it is rated at 125V, it will work safely up to 125V only :) Mar 16 '15 at 14:29
  • 1
    In fact the answer is maybe. It all depends on the detailed relay specifications. Many relays have a current rating at one voltage, and a lower rating at a higher voltage. There is, of course, a maximum voltage, independent of current and vice versa.
    – Milliways
    Mar 17 '15 at 6:51
  • The link is not good. Are you using this T010010 model? uk.rs-online.com/web/p/…
    – user31481
    Oct 28 '17 at 10:44

The part is obsolete now according to Mouser. The simple answer is no, you cannot use a 120 volt part at 220 volts. The higher voltage can breakdown the lower voltage rated parts. It really has nothing to do with the "power" rating as there will be very little power actually dissipated in the relay. The current handling of the contacts is one issue and that seemingly didn't change but the voltage rating change is basically saying that this part cannot work at 220volts.


You should not use the 10A125V relay in place of the 10A250V relay. If we use the formula: Watts = Volts X Amps. The 125 volt relay can handle a maximum of 1250 watts. The 250 volt relay can handle a maximum of 2500 watts. Wow, the 125 volt relay can only handle 1/2 the wattage. Like the 3 commenters have said, the maximum amperage AND maximum voltage requirements must ALSO be met to use the relay.

  • Agreed. Even if it "seems to work" for a while there is a very real danger of fire or electrocution if the relay specs are not met, and you are connecting mains voltage here.
    – Nick Gammon
    Aug 29 '17 at 7:09
  • 4
    Wattage is completely irrelevant: the relay doesn't handle the watts, the load does. The relevant parameters for the relay are the maximum voltage it can handle when open and the maximum current it can handle when closed. Note that it never handles voltage and current simultaneously. Aug 29 '17 at 8:05

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