Turning anything electric on or off is prohibited. This includes lights, hot-water urns, air conditioners, stoves, computers, and telephones. It is similarly prohibited to adjust their intensity or power settings.

It is permitted to set a timer before Shabbat to turn lights and certain other devices, such as air conditioners, on and off during the course of Shabbat (see below for an important limitation). The reason for this permission is that when a device is operated by an electric timer, the labor is performed as a result of an action the person performed before Shabbat, not on Shabbat itself.

It is permitted to use an electric blanket or pillow that was activated before Shabbat, but one must be careful not to remove the plug from the socket.

The use of a timer is permitted for only some electric appliances but not for all appliances. Quiet devices, such as a hot plate, may be activated by a timer. By contrast, noisy devices like washing machines may not be activated by means of a timer, as the noise draws attention, and people might suspect that the device was activated on Shabbat itself. This type of reason, called marit ayin, “the appearance of transgression,” is discussed at length in a separate chapter (p. 454).

Nonetheless, a loud electric appliance which is commonly set on a timer, such as an air conditioner, may be activated by a timer.

It is prohibited to use an elevator on Shabbat. In recent years, a special “Shabbat elevator” has been developed, which stops for predefined periods of time on each floor, without any human action necessary on Shabbat. Some halakhic authorities allow the use of such an elevator. Opinions are divided; each person should follow the instructions of his rabbi.

Staying in a hotel on Shabbat often raises halakhic problems, so one must take great care to avoid violating prohibitions. Some of the common challenges are lights that turn on automatically when a person walks in a corridor, electronic locks for rooms, automatic systems for turning on lights and appliances such as air conditioning upon entering or exiting rooms, and toilets that flush automatically.

The best solution, when possible, is to avoid all these problems by disabling the relevant systems before Shabbat and requesting a manual key to one’s room. If this cannot be done, one should obtain guidance from a rabbi who is knowledgeable about these matters.

In situations where electricity is required for lifesaving activities [pikuah nefesh], such as in hospitals or on military bases, one may use electric devices on Shabbat as necessary for these lifesaving functions.

It is prohibited to extinguish a fire on Shabbat. Nevertheless, if a fire breaks out and there is a concern that it might be life-threatening, one is permitted – and indeed obligated – to put it out. It is generally assumed that a fire does pose a danger to human life. If the fire poses absolutely no danger to anyone’s life but will cause only monetary damage, one may not extinguish it on Shabbat.