IMHO I completely know how things like this happen.  You build a Datacenter to hold say 20 full height racks.  You fill that up in a few years, and people keep on wanting to put more and more servers into that Datacenter, take over another floor or two in the building to keep up with the growth, then run out of space again, need a bigger UPS to keep all the power clean, and a bigger Generator in case the power fails and you need to keep everything going.  Big UPSs and Generators and AC set you back a few mil each but because of budget constraints you can't go for the biggest so they all run at 50% utilisation which is what you want so if one or two of them fails or is out of action you still have enough backup supply to keep it all running, you can only go for what will just keep it all going and all of them run at 90%, then the Infrastructure manager for the Centre says "you can't put any more in before you take some out".  Then project manager "A" who needs to get their project over the line complains up the food chain to the senior mgmt saying this project is vital, and there isn't anywhere else where we can house these servers, senior manager comes down to Infrastructure manager saying make it so.  Then Infrastructure manager says there is a risk and you need to accept it mr senior manager, and senior mgr says I accept the risk.

Instead of just one project have 200 projects and the problem just becomes unmanagable.  All you need is someone to do something silly say put a stack of new SAN disk in and power them all on at the same time without checking the power consumption or the current rating on the current circuit, blow the circuit because it's overloaded and kiss goodbye to it all.

Now I am not saying this is what happened at Telecom, but it is whats happened to me at a govt department 5+ years ago when you have an in-house managed datacenter where whoever screams in the right ear wins and the Datacenter manager doesn't have complete right of Veto for any new hardware.  If it were managed by a third party they know it would be their ... if it all blew up so they wouldn't let things like that happen.  Not to say that managed datacenters don't cost you 2-3X more than doing it yourself the bigger the center gets.

It's even better in this day and age with Blades, where you have a 7U blade enclosure which sucks as much power and pumps out as much heat as a fully populated rack in "the old days" holding 14x3U servers.  You can squeeze 3 enclosures into a single rack with 14 blades per enclosure and you figure it out.....

I would really love to know what actually happened, but I doubt anyone other than those in the know (who aren't talking) will ever know the full story.