There’s a reason you shouldn’t use guitar cables to connect an amplifier to a speaker cabinet, or speaker cables to connect a guitar to an amp. Speaker and guitar cables are not the same. Guitar cables are meant to carry the relatively weak signal from your guitar pickups to an amplifier. Guitar cables also need to keep interference from getting into your signal, to prevent noise and hum being picked up. To accomplish these tasks, guitar cables use a small central conductor to carry the low-level signal from the guitar to the amp and an outer shield of twisted or braided wire strands or metal foil to shield the signal from airborne interference.
Speaker cables must carry a very strong signal because they’re carrying the sound after it’s been amplified. Speaker cables need to have large conductors compared to instrument cables. However, because the signal is so much stronger than any outside interference, they don’t need to be shielded.
So even if they look the same on the outside, the two types of cable are quite different and not interchangeable. Use a speaker cable to connect your guitar to your amp, and it will be a magnet for electrical interference noise. Use an instrument cable to plug your amp into your speaker cabinet and the small conductor may not be able to handle the power output and could cause major problems.
Always use the correct cables for the job!