Okay, I was asked to move this discussion out of the modded EVSE thread, so here goes, from the top:
After receiving my modified L1 EVSE and the corresponding adapters for my 240V dryer outlet, I'm hearing significant electrical noise from various devices with speakers in my condo while charging at 240V. Most annoyingly, I hear it from my computer display (an Apple LED Cinema Display) and boy is it bloody irritating after an hour or so! It's also audible on a set of powered computer speakers as well as across all the speakers in my home theater driven by my Sony ES receiver/amp, though less so. I believe it to be power line noise (as opposed to radiant).
1) The noise is generated only when charging at 240V, not when charging at 120V and of course never previously.
2) The noise occurs with different devices (though not everything) and on every circuit I tried. It occurs on circuits with or without GFCI. These outlets do pass ground testers.
3) This same noise is audible directly from my electrical subpanel while charging at 240V. It's normally silent. (My subpanel is up in my living space, two flights above my garage.)
4) My 240V source is a dedicated 30 amp circuit for my dryer with the old style 3-prong outlet. (NEMA 10-30)
5) Two noise filters tested against the computer display didn't help. Another old noise filter (SL Waber WaveTracker) that I dug out of the closet fried itself (flash+burnt smell) when I tried to use it. (It had been sitting in storage for many years.)
I eventually broke out a handheld AM radio, tuned it to find interference and walked around to find… AC electricity in my walls!! Amazing!
Also, lots of noise down around in the garage, inside the car, at different specific points within the garage, along the charging line and the EVSE and a different kind of noise (static/white noise) around the plug adapter. But none of that is probably interesting.
Unless folks can tell me that all this electrical noise is normal and unavoidable while charging at 240V, I'm going to stop using 240V and go back to charging only at 120V. And I guess I need to get an electrician to come in and check this out. I'm not sure how I'm going to handle the raised eyebrows at the modified EVSE, but we'll see.
If you'd like to hear this electrical noise for yourself, here you go:http://crimdom.net/misc/noise-sample.mp3
And if someone would like to drop by north San Jose and plug in their LEAF here to eliminate my car (and its on-board charger and noise filter) as the issue, let me know!