If I work for one company doing maintence and I go to a competitors business to do side work doing the same things is it unethical?

It depends.
1. What do you mean by maintenance? Computers or buildings/grounds?
2. Do you have a contract that says you can't?
3. Will you be too tired to do either job as well as you did the one job?

I would call that a conflict of interest no matter what it is. Yes, unethical in your words. You have to be loyal to one if they are paying you.

It depends.
1. What do you mean by maintenance? Computers or buildings/grounds?
2. Do you have a contract that says you can't?
3. Will you be too tired to do either job as well as you did the one job?


1. Working on machines like cleaning them and oiling them
2. No contract as far as competition
3. No not tired at all still preform as well as I always have at my first job.

This is just a side job to help support my family

I would call that a conflict of interest no matter what it is. Yes, unethical in your words. You have to be loyal to one if they are paying you.

Really, pretty broad brush.

If the main place of work, is aware and approves of you working the second job, and is aware it is for the other company, there is no problem. It is only a ethics issues if it is all done in secret.

I disagree that it is a conflict of interest. That would only be so if you have knowledge of proprietary information about the machines.
I disagree that you need to tell your first employer. You don't have a contract prohibiting work elsewhere.

Based on what you have said, I believe that the answer is that the second job is ethical and that no one needs to know.

There is no conflict, nor is it unethical to work a second job, nor a need to disclose working a second job, unless it's prohibited in writing.

Millions have 2 and 3 jobs to make ends meet.

Just to make sure, The main company you work for is not in the business of doing maintenance, you just work for them doing maintenance on their machines.

If that is the case, then the only ethical issue would be if you passed along info about one company to the other or did anything that would give one competitor and advantage over the other.