i am confused, what rating of mcb used to protect l5508d1a nd l5504d2a
You can determine the rating by looking at the maximum input current and the maximum output current. Typically it could be 10A input and 1amp output or 2amp as per your part numbers. You can protect both input and output.
These units are rated at 8x 1A or 4 x 2A which is a total of 8A, hence an 8A MCB would be used. If you are in Aus, and RCD is needed on all lighting circuits and 8A RCD/MCB combo's are not redily available so it is typical to use a 10A unit. you could have an RCD upstream and use an 8A breaker to protect the dimmer, but any fault on the system that trips the RCD will also take out every other lighitng circuit fed by tht RCD. Circuit protection on the outgoing channels is not requried (Aus) but if you feel you want them you can add them. Mick
