It creates a coil like that, and inductive currents can blow both ends. I mean the miner controller + the rooter.
... Ethernet cables contain twisted pairs, and the minimum standards make your comment utterly nonsense. You shouldn't run Ethernet cables along a power line, but coiling an Ethernet cable cannot hurt anything.As suggested above, maybe lightening could cause some issues... but that's the lightening causing a problem, not the fact you coiled up an Ethernet cable.
QG