I wonder if someone can throw some light onto a problem with a new piece of kit.
Last week i purchased a Seaward NTB1 RCD isolation box, which i thought would be handy when testing RCDs without the fear of tripping the main RCD on the board of the building.
The problem i am having is, when i use this box it doesn't trip the RCD under test and just makes 2 buzzer sounds for the 2 tests.
I had the first box changed because i thought it was faulty, but the replacement is doing the same.
I'm using a PT300 for the tests, which works fine when testing RCDs without the isolation box.
Any ideas, or is it better to get my money back, and put up with tripping the main RCD each time?