What would cause my MacBook to kill AC power adapters?

I agree with Mayer your AC power is likely the cause not your MacBook if it is working correctly. You need to think what is down stream of your AC power adapter > your AC service.

You could have quite a few things going on within your AC service that can kill the power adapter:

- Poor wiring wires crossed in the AC outlet - Get a outlet tester to see how their wired. You may need an electrician to fix this if you can't see the problem when you pull the outlet and don't see the wiring incorrectly wired. Make sure you have pulled the fuse or breaker before doing this! If you still have fuses (make sure you have the correct fuses for the given line - no pennies either!) You may need to think about upgrading your fuse panel & house wiring to a newer breaker type panel as you don't have a proper ground service with a fuse panel.

- Reduce the amount of devices plugged into your power outlets/strip and/or replace the strip for a proper surge protector (get a named brand so your sure you getting something good here). If you get a lot of lightning in your area replace the surge suppressor every few years as multiple hits weaken it over time.

- Think about getting a whole house surge protector and make sure your houses ground service is good shape. No corrosion on the grounding wires or ground rod, Ground rod is correctly placed and/or you need more than one given the soil type (dry or not conductive enough). The gage of the ground lines is large enough. - Get a good electrician to review this and monitor the corrosion yearly if needed clean off the rod & rod clamp of an build up and think about spraying with a corrosion protectant.

- Bad power and/or another device within the house has a bad motor or wiring causing voltage spikes and/or leaking to ground. - Talk to your power supplier for a power meter with a logger to test your service for a good week or two. Review the trace daily to see if you can tie your usage of something to what the log report tells you. Otherwise your power service is the cause and they need to address it. You may need to get a UPS for your sensitive electronic equipment to protect them.

- The given service line is too strung out (too many outlets/lights and/or too many in use at the same time) for the service type 15/20 Amp - Isolate out the fuse or breaker and count how many outlets/lights are on the circuit. - Get an electrician in to spilt the line load at the fuse/beaker panel. In the meantime disconnect as much as you can and/or move to a different circuit which has less on it. Ideally, you should use a dedicated 15 Amp service for you laptop and a 20 Amp service for your desktop and it's peripherals.

For the last two points - A good clue you have problems is the lights flickering when you turn something on (within your house) or when your just sitting reading or watching your computer/TV (your power coming into the house is bad).