Assuming that pressing the button on most detectors is a battery test. How are mains wired detectors tested?

Hi Larry

Mains powered smoke alarms are tested just the same. The test button checks the electronics and, of course, the sounder.

Harry

Assuming that pressing the button on most detectors is a battery test. How are mains wired detectors tested?

To clarify what Harry said.

Pressing the button on a detector is NOT a battery test.

When the test button is pressed the detection device (be that ionisation / optical / other) is "fooled" into believing "contamination" is present, so the detector sounds for a short while. The battery voltage is monitored by different electronics of the detector, and if in the testing process the battery voltage becomes too low the sounder will chirp at regular intervals to indicate this.

It is the same for mains / battery / combination detectors.

We have mains wired detectors that beeped once this morning at 5.30. They did a similar thing about 2 months ago, but no sound inbetween (other than us pressing the test button on each unit). Any suggestions why this happened?

The make, model and details of the system would be needed but check out they are having similar problems to you.

My local building control officer has specified the installation of a mains operated smoke detector in the living area of my home. Is it a legal/insurance/building requirement for this to be installed by a qualified electrician? Can it be installed by a competent person who's not qualified?
Thanks
Madelaine

It appears you are involved in building regulations and you could be subject to the Smoke Detectors Act 1991 or it could be a compensatory requirement, this is why the building control officer has specified the installation of a mains operated smoke detectors. Because you are involved in Building Regulations in England and Wales, Approved Document: Part P applies which requires domestic electrical installations to be designed and installed safely according to the "fundamental principles" given in British Standard BS 7671 Chapter 13. This means you need a professional electrician to install them and certify them for the BCO to grant a completion certificate.

Following on from what Tom says, I should like to point out that although ideally an electrician should install the smoke alarms, not all electricians are Part P registered. So although any electrician can install them, not all electricians can issue a certificate that says the work complies with Part P.