It sounds like money is more important then the lives of his customers and employees. He needs a realty check.
We went by the NFPA books, so they were checked every six months, i believe this is what nfpa said. But also I worked on a Reserve base where we had more power than the outside business. But maybe you need to try this also. Is there away to shut him down or try fines. Get the health dept. involved this may help, you will probly be hated but if you save one live it worth it. Look at some of the places that have burned. I found flies by the grill and went off on the people and also last weeks fries laying around and went off on them. Let me know what happens.
I have issued a citation to the manager, $1,086.50 is the maximum fine. I am trying to see how everyone else has handled it so that if the judge ask about it, I can answer.
I have tagged and shut down the appliance and advised the business owner/manager that using the appliance would subject him to a fine and arrest. I then advised both the the police and building departments of my actions.
We require that all appliances be labeled and certified by a recognized testing agency such as UL or FM. In one case, we closed down the business until the listing was verified and repairs were made. A jeweler once installed a kiln in his place of business. I was unable to find a label on the oven so ordered them to discontinue using the appliance and tagged it. The appliance was listed by a reputable testing agency in Germany. Once it was verified that it had been tested, the Chief granted them permission to use the appliance.
You have to be careful though - not all testing agencies, outside the United States are reputable.