Printer tripping AFCI (Arc Fault) breakers: possible solution

[Sommerfeld2018]

Like several others who have posted here, I have a printer that has been regularly nuisance-tripping an AFCI (Arc Fault Circuit Interrupter) circuit breaker.   For background, these breakers look for high frequency electrical noise on the circuit that is typical of an electrical arc from a short circuit, which might start a fire.   Unfortunately it's also noise typical of some laser printer print engines like the one in my M479fdn.

The AFCI breaker on the circuit is made by Square D.   You can get the breaker to tell you the reason for the previous trip and in all cases it diagnosed an Arc Fault.   I tried the printer on two different AFCI-protected circuits and had the same result.

The triggering events seemed to involve printing something in color; it typically trips part-way through the first page, creating a bit of a mess as the toner doesn't get properly fused to the paper.

But unlike others I think I have found a workaround: an isolation transformer.   I purchased a Tripp Lite IS1000 isolation transformer about a month ago; the printer (and nothing else) is now plugged into the transformer.    I have not had a nuisance trip since I made this change.   (If I do get a nuisance trip in the future, I promise to update this post or make a followup post).

The isolation transformer is expensive but was probably cheaper than hiring an electrician to install a dedicated circuit with a non-ACFI breaker for the printer.    Unfortunately the next smaller/cheaper one they make is rated at 500W and the printer is rated at 550W.

Hope this helps someone!