A test of insulating MCB mains from CEB mains was completed between 7 and 8 July and the results are that ALL the noise signals that we know to be generated by the MCB HVAC system (the variable 50Hz sidebands from the heater and the glitches from the chillers) have disappeared from the magnetometer over the MC pipe and, more important, from the CEB magnetometers.

Attached a technical report with some more details.