What kind of hours would you work as an engineer?
Are you asking about duration-hours or hours of the day?
Duration-wise, it seems to work out to 8-10 hours a day in established companies where one is salaried (as opposed to paid by the hour). In startups it might be considerably more; they're frequently in a kind of desperation mode, trying to get a product (or a feature) out, writing press releases, hiring, trying to close on additional rounds of funding, etc. Engineers aren't necessarily directly involved in all of those aspects, but the smaller the company, the broader the range of tasks handled by any one person.
Hours of the day also varies widely and depends on the type of company. Startups might have super-flexible hours initially, but at some point they have to interact with investors or supply-chain companies or whatever, and that means having somewhat compatible hours. Companies with branches in other timezones may try to align the hours in each location for maximal overlap--or just the opposite, if they require 24x7 support. (It's much easier on everyone if the US engineers handle half the day and the India folks handle the other half; it's daytime for all involved.) I've worked in a fairly conservative semiconductor company, where almost everyone showed up between 7:30 and 9:30 and left about 9 hours later; I've also worked in a number of software companies, and they tend to be much more flexible. Currently I show up around 11:15 and knock off anywhere from 8:30 to 10:30pm, depending on how my project is going and how tired I am toward the end of the day. (I commute by bike, so avoiding traffic is a key goal for me.) I try to average 8 hours of actual work per day, but that can dip as low as 6.5 or go as high as 10.5 depending on various factors.
It really depends on the company and industry you are working for and what project you may be assigned to. You could be working for a major defense contractor that are trying to meet a certain deadlines that would result in greater profitability for the company should they deliver early. This could result in an all hands on deck scenario where the entire team works 10 or even 12 hours a day for an extended period of time. The semiconductor industry is another where their engineers work and alternate work schedule with 12 hour shifts around the clock.
In general many employers have an eight hour day but to be a top performer and move up the ranks in the company it is not unrealistic to work 10 hour days.
Great question. Usually it is 8 hours a day and 5 days a week, but sometimes depending on project we work extra hours and on weekends if the company requires something to be turned around very quickly or if some existing process breaks and a fix is needed immediately as it could be causing loss of service to customers or a loss of reputation to the company. Hope this helps.