can I use a 240w cable on my 2020 MacBook Air
I have a Retina, 13-inch, 2020 and its cable just broke
the cable it came with was only for 30w
im scared it will be too much for the laptop
MacBook Air 13″, macOS 14.4
Question marked as
Using a cable that is rated for 240 watts of USB-C Power Delivery should not hurt the laptop.
The way that USB-C Power Delivery works is that the two sides negotiate how much power to deliver, in which direction. The original standard allowed up to 20V at up to 5A for a total of up to 100W. The revised standard allows up to 48V at up to 5A for a total of up to 240W.
The two sides are supposed to agree before sending a lot of power over the wire. As another safety precaution, cables supporting Power Delivery are supposed to have embedded chips to let devices know that they support USB-C Power Delivery. Every USB-C cable is supposed to be able to safely carry 5V @ up to 3A (up to 15W) of traditional USB power; but if you try to use a cable that ISN'T rated for Power Delivery for that purpose, devices should notice the absence of the chips and refuse to, say, send 100W over that wire.
A cable that can safely carry 240W (48V @ 5A) will be able to safely carry whatever lower amount of power that your MacBook Air and your power adapter negotiate. The mere fact that the cable can carry 240W will not lead your power adapter to dump 240W onto the wire if it is incapable of supplying it, or if the Mac can't handle that much.