At home? No, you shouldn't be responsible, since you're relying in good faith on the services of a purportedly-qualified professional. On an industrial worksit

At home? No, you shouldn't be responsible, since you're relying in good faith on the services of a purportedly-qualified professional. On an industrial worksite? Absolutely, the owner should be responsible for safety. Otherwise it's too easy for big companies to throw up their hands and say "oh, that tower crane that collapsed and killed a bunch of people on our construction project? Sorry, it's owned by a shell company in China. Good luck collecting any damages from us!"