I say “seemingly out of spec” because I am not an electrician, and this requires more understanding of wire classifications than I possess. Regardless, we found a story a little while ago about devices that ship with power cables that are labeled for voltages and amperages that are significantly lower than what they are capable of carrying.
The minimum requirement for cables with a C13 connector is American 18 gauge (AWG), and they must be able to carry 10 amps. I own the device from the blog posting, like many others at PC Perspective. Again, the device itself (minus the cord that plugs it into the wall) is perfectly fine. The allegation is that the power cord (that goes between the wall and the transformer power brick) cannot carry its full, labeled wattage. The head claims that it can carry 250V at 10A, which is 2500W.
My cable, close up.
We cut open the insides of the cable to see what gauge wire was used, and we were able to remove the insulation with an 18 gauge wire stripper. This is where my lack of applied electrical skills fail me. The power cable feels as flimsy as a quarter-inch audio cable, but I am not qualified to measure the actual internal wires' thickness. It might meet the minimum (18 AWG) requirements, or it might just be thick insulation. I wouldn't trust it, especially not at hundreds or thousands of watts. The blog post author apparently tested their own cable under load, and they claim that it started to melt at 2.6A 123V (320W).
The blog author's wire vs a standard cable's wire. It's hard to tell how thin the Vantec one is, because the standard cable was twisted.
Image Credit: Fry's Acid Test
Now, to power a single hard drive and USB controller, you are not going to be drawing those hundreds or thousands of watts from the wall. The main concern is if you swap cables around with other devices. For instance, if that cable would be attached to a high-end gaming desktop, then it could easily see wattages in that range that are sustained for most of a play session, or even higher.
So I guess the takeaway from this is do not trust every power cables that you receive. Make sure your high-power devices are using the cable that came with them, or one from a vendor that you trust. Just because it says it can handle any given load, does not mean that it can.