Blue Elephant is biting me

[m_c]

If things aren't earthed properly, then the various filtering capacitors in the drives/PSUs can cause floating voltages.

So I'd want to know why you have a "floating earth"?
All metal parts of the cabinet/machine should be earthed.
If they're not, then I'd be looking to see why they aren't.
It could be that somebody has disconnected them as a bodge to stop an RCD tripping, as filtering capacitors can leak enough current to earth to trip RCDs, and with the number of drives in your machine, it could be leaking enough current to trip a typical 30mA RCD.

[jaypee89]

If things aren't earthed properly, then the various filtering capacitors in the drives/PSUs can cause floating voltages.

So I'd want to know why you have a "floating earth"?
All metal parts of the cabinet/machine should be earthed.
If they're not, then I'd be looking to see why they aren't.
It could be that somebody has disconnected them as a bodge to stop an RCD tripping, as filtering capacitors can leak enough current to earth to trip RCDs, and with the number of drives in your machine, it could be leaking enough current to trip a typical 30mA RCD.

The floating earth appears to be by design, All the standard expected earths are connected together on a terminal strip mounted inside the cabinet. The actual earth from the supply is connected to the neutral points on the system. It's a 3 phase no neutral system.
That's an interesting comment about the capacitors leaking to earth, something I can test further with

[m_c]

The floating earth appears to be by design, All the standard expected earths are connected together on a terminal strip mounted inside the cabinet. The actual earth from the supply is connected to the neutral points on the system. It's a 3 phase no neutral system.
That's an interesting comment about the capacitors leaking to earth, something I can test further with

That doesn't sound right.
The standard earths should be earthed, as that's safety critical.

I'm not sure why you'd earth the neutrals on a non-neutral system, or even why they'd have a neutral if it's a no-neutral machine.
Are there any transformers in the machine to isolate/step down voltage for anything?