After generator was installed (Generac Model 0052540 w/Auto Txfer) started to experience whole house "flicker" whenever any appliance turns on... tricky thing is, this happens even when we switch to 100% generator power. Power Co and Electrician have gone over "everything" and come up with nothing. There is also a sharp quick buzz sound from somewhere outside just prior to the flicker. Thank you for your suggestions.

Sometimes a loose connection on the neutral in the meter base will cause this. Have the power co check it out.

The neutral in the meter base is not it. The neutral from the genset comes into the ATS, and then to the Neutral in the Main Panel. When on gen power, there is no current flowing, or at least should not be, in the neutral in the meter.

A loose neutral in the meter would only be a problem on utility power.

I am assuming this is a 2 pole ATS. Even if it is a 3 pole, with one pole switching the neutral, still no effect by the meter is expected.

Thous the flickering does sound like a neutral issue, there may be a loose connection in the ATS or the main panel.

For anyone to trouble shoot this from here, you really need to pin down where the buzzing is coming from. Some photos of the inside of the ATS and panel would help, along with photos of the outdoor portion of the service.

I have to also assume everything is done properly, such as grounding, etc. so any additional details would be helpful.

Thank you for the response. tkrussell I sent you a personal message, sorry was not aware this method is not suggested as indicated by the admin. Just now. Please advise, I shall repost if necessary. Many thanks

Re-post if you like. Admin asks that PM messages be avoided so that other people can see the questions and the answers and hopefully benefit by the responses.