Can I pursue a PhD while working as an Instructor/Lecturer? So, I'm applying for jobs as an instructor/lecturer.  They explicitly only require a master's degree, which I have, in addition to some valuable industry experience.  It's plausible that I could get one of these jobs.

If I get one of the jobs, I would be hoping to potentially stay in academia for longer, so logically it would help me to have the PhD I currently lack.  Ideally, I'd like to pursue my PhD part-time while working as an instructor.  My thought is that this would give me the opportunity to eventually get a professor position, later in my career, once I complete the PhD.

My questions:


Is this something that universities are okay with their instructors doing?  
Or is it not okay for someone to be teaching undergrads while simultaneously doing graduate research?   
If I wanted to do this, would it be more appropriate to pursue the PhD at the same institution as or a different institution from the one that I'd be working at?


Some additional helpful info:


All of the schools that I'm applying at have part-time PhD programs, so I have no reason to believe that the part-time study schedule is an issue.
I'm not in the U.S., so the specific rules of American academia don't necessarily apply.  For example, here, we rarely have grad students teach classes.
Most universities are fine with having PhD students working as instructors/lecturer/teaching assistant at the same time, and it's actually quite common. I have personally been teaching at undergrads level while doing my PhD, and most of my friend who did a PhD were in the same situation. 

However, it depends on the amount of hours you are spending a week with teaching: if it's taking all of your time, you might not be able to do research in good conditions, and it might be hard to find a professor that would agree to supervise you if you're not available to work on your PhD. Basically, if you combine a part-time teaching/part-time PhD, that should be fine, but if you combine a full-time teaching with a part-time PhD, that might not reasonable. 

Concerning where you should apply for the PhD, in general, you can do it in a different university than the one where you're teaching. However, in some cases, it might be more interesting to do it at the same place because you might not have to pay the tuition fees.