I doubt they sparked (tested) the installation correctly as they damaged my power supplies.
I am almost but not quite certain it is their fault. They did a good job otherwise and I want to stay on the right side of them. As they are nice and do a lot of work for us. Also two of them were quite young.
The standard they test to is a local standard, named AS/NZS3000. Which probably has derived the insulation test based on some international standard.
The test is pretty easy.
Just Apply 500vdc (high impedance source) between each of the 'live' conductors(including Neutral) and Earth and make sure there is at least 1 Meg ohm of resistance.
In Australia we have a slightly modified TN−C−S Earthing system. So at one point in the building the Earth is shorted to the Neutral.
If the link between Earth and Neutral isn't disconnected before testing and your device in in circuit then you will get 500v into the device from Active to Neutral.
I have myself once damaged an oven doing this test, so these days I am careful about it. Most devices wouldn't have a problem with this.
One thing I forgot to mention was that the devices are hard wired in, and have circuit breakers in, the AC devices have RCDs on the output.
They all have power into the box.
I was hoping they were galvanically isolated but now I am not so sure.
I had a quick look for schematics but haven't found any yet.