They make clip on lockouts for residential breakers. https://www.amazon.com/dp/B004J173I8/ref=twister_B007NAGJJG?_encoding=UTF8&psc=1 https://www.amazon.com/dp

They make clip on lockouts for residential breakers. https://www.amazon.com/dp/B004J173I8/ref=twister_B007NAGJJG?_encoding=UTF8&psc=1 https://www.amazon.com/dp/B004J173I8/ref=twister_B007NAGJJG?... Personally, I just lock the panel. If your panel can't be locked a big piece of masking tape across the door, holding it shut, with "NOPE. call <you>" written with a sharpie should do the job. :) FWIW, the first photograph in that WP article with the tagged panel is one of mine... from close to 15 years ago.