What do the measures on this component mean?

Related post: http://forum.arduino.cc/index.php?topic=442047.0


I am trying to use the following component: http://tinyurl.com/zoa25ft . What do the measures on the component mean? Can it handle electricity from 120 volts?

The circuit in question is: http://imgur.com/a/JAL2B

If the switch is open, then what is happening to the electricity? Will the switch overheat, bust, or etc?

It's rated for 250V, though I would be hesitant to rely on those wimpy little relays for handling line voltage.

If the switch is open, no electricity will flow.

It seems that you are unfamiliar with basic electrical principles, like the concept of a circuit. You should not be working with mains voltages with your current level of expertise.

Do not create multiple threads on the same topic.

The right side mark is for a UL recognized component.


AC voltage is easier to open than DC so it has a higher rating. As far as why are the numbers different? It has to do with the standards used to test. I suspect it can open 10A at 250VAC in the USA just as well as any place else, but if it burns down my house (on a 230V circuit) then insurance may be able to deny payment because it was only rated to 125VAC. Also since it is only a recognized component (and I did not pay an electrician), that may add some strength to their ability to deny payment.

Here's the datasheet for the SRD-05VDC-SL-C, which explains the part number.

The contacts are Form C, which means it has 3 contact terminals NO (normally open), COM (common) and NC (normally closed).

The contacts have 5 different ratings based on the type of load being switched, the voltage, and whether its AC or DC.

Not a great choice for switching a refrigerator/freezer load, especially if its frostless, as the defrost cycle can can use 800W (6.7A @ 120V). The compressor load is inductive could be up to 400W (3.3A @120V). The relay contact rating for inductive load is only 3A 120VAC.

It would probably work but expect reduced life expectancy and lower reliability.

An induction motor load requires a proper snubber circuit across the relay or it will fail pretty
quickly due to heavy arcing.

Surely the better solution is to replace the broken thermstat on the fridge? It ought to be a
standard spare part.