<html><head></head><body><div class="ydp1cc9f7ccyahoo-style-wrap" style="font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:16px;"><div><div dir="ltr" data-setdir="false">Perhaps having ETC just work on one unit, to settle on a cause before you take any further action.</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">And while it is possible there was a bad batch, it is also possible that something in your facility. E.g. another piece of equipment failed and momentarily provided an inductive "kick" to much higher voltage. Some units survived the over voltage and some didn't. Or perhaps a lightning strike. While a lighting strike may affect other equipment, it may also have been more limited in how much of your building was affected.<br></div><div><br></div><div class="ydp1cc9f7ccsignature"><div dir="ltr" style="font-family:Helvetica, Arial, sans-serif;font-size:16px;">-Joe<br></div></div></div></div></body></html>