Under what circumstances is it safe to climb a tower without a helper or observer?
Why Tower climbing is a high-risk activity: a fall, a dropped tool, a sudden illness or an equipment failure can leave a solo climber with no way to get help. Standard amateur safety practice is that someone should always be on the ground to observe, keep the area clear, handle ropes and call for assistance. That applies no matter how routine the job seems or how high you go.
Watch out The choices that carve out exceptions for no electrical work, no mechanical work, or heights under 20 feet all sound reasonable, but a fall from even a short height can be fatal, and the pool allows no exception at all.
Tower questions with an absolute answer: never climb alone. No height or task makes solo climbing safe.