"The likelihood of the failure is low, provided you have a competent electrician."
Bollocks. The likelihood of problems is going to be medium, at best, in anything other than a brand-new datacentre.
Being a competent electrician means you can rely on them not doing anything 'directly dangerous' it says nothing about their ability to understand a complex system that has been modified, probably outside of the applicable regulations, in places that are simply not visible. For example, a competent electrician will know that mixing phases from a three-phase supply is 'a bad thing'TM but there is no easy way that I am aware of to test whether some incompetent has actually done this.
As with anything, you have to ask whether the operation is routine for that electrician, or is there any chance of a mis-understanding? I don't blame the sparkies for this - clearly they were just chucked in there and told to get on with it - no doubt without anyone mentioning how important it was.
Biting the hand that feeds IT
