How much do relays stress the Pi?

[6hearts]

I'm making a element, where my RPi zero turns on/off 4 relays (REES52 Optocoupler 4 Channel 5V Relay Module). I want my circuit to work constantly for as long as possible (ideally for several years) and the relys will be powered on for about 50% of the time days at a time.

Is it OK to connect the relay module power to the 5V pin of the rpi zero or should I power the relays with an external 5V power supply?

My problem is that since I want the relays to constantly work for years, I'm not sure I want to stress the rpi unit if it's not absolutely necessary. On the other hand, it could be that the relays consume very little power and my rpi unit just won't care that much?

[gordon77]

As long as the relays are isolated from the GPIO by optoisolators or transistors /fets which don't exceed available current, and you don't draw too much current from the 5v then there should be no stress

[6hearts]

Drawing how much current from the 5V pin is safe for long-term usage?
I know there is no definite answer, but maybe just an approximation what current I better should not exceed for lets say I month?

[gordon77]

I think a relay board will take around 75mA per relay, so with a decent psu, eg the pi 2.5A, l wouldn't expect a problem. May depend on many USB devices etc you want to use.