Answer:  The State of California and the City of Los Angeles both have laws that require smoke detectors to be installed in all "dwelling units intended for human habitation." However, in a single family home, this is primarily accomplished when a property is sold. If you mother has been living in her residence for many years, she probably doesn´t have other safeguards like water heater strapping or a gas shut off valve. In her case, ignorance isn´t bliss. It´s dangerous.

Most residential fires are caused by fireplace sparks, candles or electrical problems. According to the Los Angeles Fire Department, studies have shown that in residential fires causing death, 60% of those residences did not have smoke detectors, had disconnected the smoke detectors, or had dead or missing batteries.

In the City of Los Angeles, smoke detectors are required in each sleeping room and the areas giving access to them. They need to be located on the ceiling at least four inches from the wall or on the wall four to twelve inches from the ceiling to the top of the detector. Smoke detectors in a single family home can be of the battery-operated type or wired into your house electrical system, otherwise known as "hard wired" as required in two or more units. There are also dual function detectors that are hard wired but have a back-up battery in case of power failure. Tests have shown that smoke detectors of either the ionization or photoelectric type should provide adequate warning to the occupants for most residential fires. Ionization detectors respond slightly faster to open, flaming fires than the photoelectric type, but the photoelectric detectors respond faster to smoldering fires with little or no visible flame. Choosing between photoelectric or ionization type is up to you as both types meet the accepted safety standards.

If you choose battery operated smoke detectors, they must be maintained and the batteries be replaced regularly. Batteries should not be removed because of nuisance alarms such as what happens to your aunt. Suggest to her that she install a door to close off the kitchen. If you use hardwired detectors, consider purchasing a couple of battery type and mounting them in strategic places as a back-up system.

Relatively new is interconnecting smoke detectors which produce a simultaneous response to the presence of smoke. When one detector is activated, all detectors sound. This network of fire protection alerts the whole house. However, be warned that fire can damage the wiring of the home. This compromises the integrity of any hardwired smoke detector unless it also uses a battery back-up. While costs can range from less than $500 to a few thousand dollars for the electrical enhancements that create a smoke detection network, these expenses can often be reduced by combining the work with a remodeling project or other electrical improvements that you can suggest to your mother.

Because your mother is elderly, there are certain considerations that should be addressed. In general, households with elderly or handicapped occupants need a higher level of protection in order to provide additional escape time. As an example, a supervised alarm system where the alarm is monitored by an alarm company that would call the Fire Department, or in the case of someone with a hearing loss, detectors that activate lights, bed shakers or fans.