What education, experience, licenses and/or certifications are required to do industrial wiring repairs in PA. Are there voltage limits in which you can work based on education? What makes a person competent?

Cindy,
To legally perform electrical work for the public you need to be a licensed electrical contractor by the State of Pennsylvania. (along with a business permit... etc.)
You can be employed by a licensed electrical contractor without any training at all...
There used to be a 50 volt limit for those who were not licensed for instance communications workers and HVAC installers to do low voltage wiring without a license...
I believe this has changes to 25 volts or less and now at least in NJ even home improvement contractors need to be registered.

What makes a person competent? A better reference is what is a "Qualified Person"?
This is defined in the electrical code as:
"One who has skills and knowledge related to the construction and operation of the electrical equipment and installations and has received safety training to recognize and avoid the hazards involved". (NEC Article 100)

So does that mean that a licensed electrician is "qualified" to do any kind of electrical work?
Speaking for myself, NO, certainly not there is always more to learn...

Cindy, I apologize, I digress a bit... did you have a more specific question?