According to the Tewksbury TWP WEB site FAQ (see reference below) all plumbing and all electrical work requires a permit. I would expect (in my opinion) they are referring to all significant work and not necessarily minor repairs. I would speak to Tewksbury TWP code officials for the exact definition of the scope of work that requires a permit.
If the electrical and plumbing required more than just normal repairs, i.e. replacement of portions of these systems, I would certainly look at having the work inspected by a professional, licensed and competent plumber and an electrician. If these items were required to be permitted and were not you might always encounter a potential for not obtaining a certificate of occupancy or potentially issues obtaining insurance for the property. To use an old phrase "When in doubt, check it out!".
Good luck on your project!
"Knowledge is power, but sharing knowledge brings peace!"
What requires a permit?
Permits are required for the following work:
Any type of new building (homes, sheds, barns),additions, add a level, dormers, swimming pools (above and below ground), sheds greater than 100 square feet (all sheds need zoning approval), finished basements, fireplaces and wood stoves, pole barns and run-in sheds, hot water heaters, boilers, furnaces (new and replacements), new air conditioning, gas piping (to grills, gas logs and gas appliances), sewer and water connections, radon mitigation, oil and gas tank removals, fire and burglar alarm systems, all plumbing work, all electrical work, siding, roofing, windows (new and replacement), oil and propane tanks (new and replacement).