Saftely testing conditioners ...
I PAT (electrical safety) tested an IEC cable last week (video here) using our certified PAT test machine and it failed although it seems to work perfectly and there is no problem with the three conductors end to end. The cable included a 'surge protector' and it seems that this protection device proves a permanent leakage path from live/neutral to ground that takes the insulation leakage outside the safety standard. The test box does not know and does not make any allowance for the anti-surge drain circuitry inside the cable - it just senses a leakage path.
So, whilst not personally a believer in power conditioning/surges here in the UK with a well behaved spike-free supply, it could well be true that there are real measurable differences between the supply delivered to your equipment directly or via a conditioner/spike eliminator. This automatic tester will not proceed along the full test routine for this cable because it fails the basic safety test. Strictly speaking, I should discard it.
Serious point: how confident are you about the electrical safety of your system? Has it ever been checked by a qualified person?
Alan A. Shaw
Harbeth Audio UK