I noticed the same thing with several strings of LED Christmas lights. Though they are on a regular circuit breaker. I assumed something was wrong with the switched cord I used. It looks like an extension cord but has a switch on one end and combination male/female plug on the other end.

It's interesting that the blue and green are the brightest, red barely glows, and the yellow and orange no glow at all. Although they don't glow bright enough to see where your going.

Grud,

The arc fault breakers that I have (in MN, USA). Look like a regular CB except they have a yellow test button and if you pull the panel cover they have a white wire coming from inside that is hooked to the ground / neutral bus.