The cable coming out of my dishwasher ends in an L5 plug of the type that has screw terminals inside for attaching wires. In my continuing quest to inspect all the accessible electrical connections in my new house due to the number of problems I've found, I opened this plug up. Upon doing so, I discovered that the neutral wire was loose and blackened, and that the entire screw terminal was rusty-looking and surrounded by an area of charring (probably someone who didn't understand that you need to rotate an L5 plug to disconnect it yanked too hard). The external neutral prong was blackened as well, but the blackening was so uniform that it looked intentional from the outside, like they just made one prong a different color.
Obviously the plug needs to be replaced, and the burned wire will need to be trimmed back at least a few inches. And even though it looks ok, given that the prong got hot enough to turn black, I should probably replace the receptacle it was plugged into as well (I think I will actually ditch the plug/receptacle entirely and direct-wire the thing; the manual says that's fine). Is this enough, or should I replace the entire burned wire and/or go through the whole circuit looking for other areas that might have overheated? And is it possible there is damage to the dishwasher itself (it's been running fine, as far as I can tell)?
In case it's significant, I should mention that this is a multi-wire branch circuit where the previous owner/my nemesis had connected both hot wires to the same leg inside the panel. This has been corrected, but the neutral could have been overloaded in the meantime. However, my intuition says if that's what was behind the charring, I'd be seeing it all over instead of at just one connection. Plus, based on their documented wattages, the two appliances on the circuit (disposal and dishwasher) shouldn't exceed 15 amps even when both run at the same time.
Best Answer
L5 is rare in residential. L5 and hardwiring would increase cost to maintain the dishwasher or disposal down the line.
I would trim the cord like you're thinking, and replace the outlet too. But I'd say you should install a GFCI there instead of hard wiring it, and here's why:
The dishwasher and disposal both are obviously going to be in contact with a lot of water which (if they break) could leak current to ground through your plumbing (bad bad bad).
It's handy to be able to unplug these things in a pinch, and it's nice to have a second outlet there in case you need to plug in a power tool or a charger or something later.
Unless you would have to move the dishwasher to reach the outlet, replace that L5 with a GFCI.