"I have installed 5 of these at customer sites to date, and have had no problems or call backs.
Pressing the test button causes a 35mA current to flow between live and earth, this trips the RDC to verify its operation. It will also trip the RCD, if fitted, in the main board. It most certainly will NOT trip the 100A main switch or any of the MCB on the board.
The last reviewer point is not valid, as there is no point in installing a RCD protected Spur in a house that has RCD protection in the main board. If you need to fuse down, then just use a fused spur."
"These are dreadful quality . Purchased two of these. Test button didn't work on one (physically faulty out of the packet), and fuse holder snapped on other one first time. Both binned and replaced with Product Code 40097 instead. Much better layout of terminals and more robust. I'm annoyed with myself for having bought them in the first place - should have known better."