I had a timer switch on my front porch lights that worked great. I recently had a generator installed in my home. The generator is 13Kw and doesn't do the entire house, but mainly the essentials. the day the generator was installed, my front porch lights started flickering when they turned on. I replaced the timer switch with a standard switch and they worked just fine. I then replaced the timer with a new one and it does the same thing. The gentleman who installed the generator says that he had nothing to do with the flickering lights, though it seems coincidental that the day he changed the wiring for the generator, the problem occurred. Is there anything I can do before I call another electrician?