Accenta Mini House alarm problem?

Help! Every time we switch the electricity off in the house, the alarm goes off. This is highly stressful when undertaking electrical repairs etc. When the power is off, the alarm keypad doesn't work and so we can't punch the code in to disarm the alarm. As soon as the power is switched back on, we are able to operate the keypad. Am I missing an obvious trick here? The alarm is an Accenta Mini. Thanks