Tests showed fluorescents causing interference to AT&T 4G service.

Suppose you have a non-FCC-related business – a hair salon, let’s say. And suppose it uses fluorescent lights. You wouldn’t think that that alone makes the business subject to FCC jurisdiction.

Ronald Bethany probably didn’t think so. He runs the Perfect Cuts Salon in San Antonio, Texas, in half of a tiny strip-mall building. Hairdressing does not come among the FCC’s stated responsibilities.

But radio interference does. The salon’s fluorescent lights emitted a stray radio signal at 705 MHz, part of a band licensed to AT&T for the delivery of 4G service to smartphones and tablets. This particular frequency is used for transmissions from a mobile device to a cell tower, such as the cell tower that rises up directly behind the Perfect Cuts Salon.

When AT&T received interference, it probably suspected the strip mall, as this kind of interference usually does not travel far. An AT&T staffer stopped by and, presumably with Mr. Bethany’s consent, turned the salon lights off and on. Sure enough, the interference went off and on at the same time. Mr. Bethany contacted General Electric, which made the lights; GE offered to replace them. So far, so good.

But Mr. Bethany turned down GE’s offer. He wanted cash instead so he could handle the replacement himself. GE refused. AT&T, still getting interference, went to the FCC, which sent an agent to the salon. Although this time Mr. Bethany did not permit the on/off test, the agent used direction-finding equipment to confirm that the lights were causing the problem. The agent told Mr. Bethany he had to fix them. Mr. Bethany refused, unless someone paid him.

Now the FCC has upped the ante. It sent Mr. Bethany an official citation that requires him to fix the lights or face possible financial penalties. And, yes, the FCC can do that.

Radio interference from non-radio devices has been popping up lately. We saw another lighting-fixture case just a few months ago that also involved 4G frequencies, and before that, a problem with a well pump. There are no technical standards for these kinds of devices, as regards radio interference. In practice, though, in the aggregate, they probably cause more trouble than do the closely-regulated transmitters and digital devices.

But the interference is simple to fix. If your phone or tablet is not responding properly, you can always try turning off the lights.