Hello,
I have 2011 Escape XLS - bare bones as possible.

Most things I've been able to muddle through with the help of this and similar forums. But this has got me perplexed.

I was installing a second power socket by tapping off the cigar lighter power lines. After several fails, I removed everything and checked voltage to the wires that connect to the original outlet. With the truck off I get ~11.6 volts. With the truck running it reads ~12.4. I checked with multiple meters, and checked alternator output @ 14.5 volts. I realize that running at least 12v should be sufficient to operate anything plugged into the outlet, but it does not not seem to. I also did check for a short using the original wiring and it showed 0 ohms. I would think that if a fuse had blown I should see nothing at the cigar lighter outlet. Right? 

Any ideas as to why this is happening?

Make: Ford
Model: Escape
Year: 2011
Trim: XLS FWD
Style/Body: SPORT UTILITY 4-DR
Engine: 2.5L L4 DOHC 16V

 

Something you need to keep in mind,
Power sockets are protected by fuses to limit current draw. If that number is exceeded the fuse will open and no power will get to the socket.
If you tap into that circuit and have 2 items loading the circuit and exceeding the fuse rating the fuse will do it's job and open. So we should know just how much current your items will be using.
It is better if you also install a fuse to protect the second socket. Things do happen and that is the better way to go.

Now to the problem at hand,
There should be the same voltage at the socket as at the battery, UNLESS, there is a poor connection in the line from where the line starts to where you are getting the reduced voltage. You have the meter ,now all you need to do is load the circuit and do voltage drop testing at all the connections involving that socket. The connection has to be pretty bad to show a drop of 0.8 volts with no load. What is the voltage at the battery with the engine off? That is our starting point. Before going any further that number is important to know.

 

It's very possible that that is the correct voltage. Much of the interior is fed a regulated power source, and 12 volts plus or minus half a volt sounds fine. Find the fuse that feeds that power outlet and test the voltage there. Odds are it will be the same, and normal operation.

If you want to be sure, put a decent sized load on the power outlet. If the voltage doesn't change then its how its supposed to be.