Last night Walt escaped a plastic zip-tie handcuff by using electricity from a household socket to create an electrical arc that melted the plastic. Not to belabor this, but when you short out a household electrical socket, this is what it looks like:
There are sparks of hot metal that burst everywhere, and it only lasts for an instant because the circuit’s breaker or fuse pops. It’s also probably going to complicate things to be connected to a very well-grounded metal object like a radiator — to say nothing of stripping the live wire with your mouth, which is wet and much more conductive than skin, producing a circuit that flows directly through your heart as it heads toward your earthed left arm.
In general, that’s how household voltages can kill you: by overcoming the actually-pretty-high resistance of your skin and disrupting your cardiac function. It takes a lot of juice before electricity starts killing you through other means (basically: by cooking you).
On the other hand, if you grant the implausibly-persistent arc welder effect (perhaps Vamonos Pest has a dangerously configured but simultaneously robust electrical system), the grounded radiator would presumably have allowed Walt to apply it against the part of the plastic ziptie that anchored him to the radiator, rather than producing an unnecessary (but dramatic) act of self-mortification.
So yeah: it’s implausible that he would’ve survived the wire-stripping without serious injury. And even making some allowances for an unusual electrical system, Walt could’ve done something less painful.
UPDATE: in comments it’s been pointed out that Walt turned off the power while stripping the wires. I don’t remember that at all, but that’s probably just my own lousy memory. The stuff about the electrical arc still stands, though.