relay durability

[Sharon24]

i amm working on automated aquarium light...

and its going to be on a relay

 

now my question is the relay is strong enough to switch 220v for 4 or 8 hours a day?

any alternatives?  

[W-L]

3 minutes ago, Sharon24 said:

i amm working on automated aquarium light...

and its going to be on a relay

now my question is the relay is strong enough to switch 220v for 4 or 8 hours a day?

any alternatives?  

If your want it to be silent and not click a relay every so many hours you could get a solid state relay to switch the main power on and off the the lights. 

 

[DragonTamer1]

A relay's longevity is not usually measured by the amount of time it is on or off, it is usually measured in the number of cycles (the act of the relay turning on or off) that it is expected to go through before failing (usually 10,000 cycles for very cheap and 100,000 for a good one). The switch inside the relay can also accumulate carbon over time which will shorten it's lifespan, though not by any meaning full amount.

 

A relay also has a contact rating and it is important not to exceed this. You will need to look into how many amps your light will draw at 120V (assuming you are on the North American power grid), and you should look for a relay that can handle twice as many amps at that rated voltage.

 

A solid state relay takes the mechanical aspect out of switching but also is more sensitive to over-voltages.

 

A list of parts with the maximum contact current of 20A. Not all have an AC rating for the contacts but it's usually 10 times more voltage than the DC voltage with the same amount of current.

 

http://www.mouser.com/Electromechanical/Relays/_/N-5g31?P=1z0x3ca&Keyword=relay&FS=True