Here is a general idea of a MOSFET alternative for switching the light on and off.
Click to simulate in Falstad.
You can click the switch and the H/L input to see how it operates while running the simulation.
The p-channel MOSFET in series with Light 1 could be FQP27P06.
The n-channel MOSFETs are of much lower power.
Using MOSFETs eliminates both the RFI/EMI ...
There are two things to tackle in your schematic. First is snubber networks. These are used to aid in the prevention (or rapid extinguishing) of sparks between the contacts of switching gear (like relays). You should attach one across the contacts of each relay. It is these sparks that create most of the "airborne" EMI.
A diode across a relay's ...
For those, who are stumbling over this old thread and @igor-liferenko, since this board is still quite common:
This board definitely does NOT invert the inputs.
The comment of Igor Liferenko "tested it and I can say for sure that this board inverts the signal (on low input, there is power on output, on high input, there is no power on output)." is ...