Ic it wasn’t obvious already, don’t use chargers with damaged cables. Even if the shocks aren’t bd enough to get you to stop, the fire risk of sending 180W through a damaged cable is probably not worth it.
If you buy a cheap, off brand charger, keep an eye on it while it’s plugged in. I’ve seen several models catch fire. This was a problem in the 60W charger era, and it’s only gotten worse.
Some laptops allow faster charging than what the charger they came with can provide, and their chargers can usually power more than other models need. The 180W charger that came with your laptop is enough, no need to spring for the 240W. Unfortunately, at the time this laptop came out, there was no way for a standard like USB to provide this much power, so you’ll have to stick with a Dell charger. You can try buying similar “for parts” laptops off the internet if you want to get a good deal.
When I doubt about compatibility, you can always check the online manual for recommended part numbers, or call Dell to ask. I don’t think there’s that much variety in Dell chargers these days.
If you want to be sure not to get shocked again, buy a new one and be careful not to damage it. Hard to tell what state second hand chargers are in.