The box for my burglar alarm makes a constant humming noise. This is the main system box not keypad. It is a bosch alarm and is wired into the house so I can't turn it off unless I turn the mains power off. It has wireless sensors which receive signal from antennae on the box. The box is in my bedroom so the humming is driving me crazy at night. Is it normal for alarms to hum?

Is the humming new, or did it always do it? Most likely the noise is from a transformer that steps down your house mains voltage to something lower (like 12 or 24 volts). Transformers can hum, but some more than others. If your unit is new, I'd argue for a replacement. If it is not new, then you might try to replace the step-down transformer. If you do this, I'd make sure it is of the proper capacity for your system, as an overloaded transformer will certainly hum.

Best of luck,
WallyH