I was trying to give a practical example of a grama the other day, and couldn't think of one. While there are plenty of devices which employ gramas deliberately (grama switches, shabbat electric wheelchairs, etc.), I couldn't think of a simple example people actually encounter in normal life that would be considered a grama. Can anyone help me out?
If you leave someone's front door open, and their dog runs away, that is a gramma (bava kamma 55b).
If you startle someone and they bang into something and hurt themselves, that is a gramma (bava kamma 56a).
One classic example is person A throwing something off of a roof, and person B removing the cushion before it hits the ground. Person B performed a damage in the form of a Grama. So an everyday life example that would fit like that would be removing a safety from a device, where someone else then comes along and triggers it. A bit dated (who sees a fuse box anymore?), but someone who replaces a fuse with a piece of metal that won't break when overloaded, which then causes an electrical fire when someone overuses the electricity would be an example of Grama.
This is assuming you distinguish between Grama and Garmi in the content of the action itself. Otherwise, burning someone's loan documents causing them to be unable to collect a loan (which is Garmi) is another example.
Sources at the link. The fuse box example is unsourced.
A "shabbos mode" oven that allows you to reset the temperature on Yom Tov after a random delay would seem to be an example. A hot water heater would not be grama because you are adding the cold water as you are taking away the hot water.
There is a device that claims to allow hot water to be used on Shabbot using a "double random" method and keeping the temperature just below "yad soledet bo" but I have only seen ads for it and do not know the details. They do claim to have a haskama from some rabbonim whose names I recognize as reliable, but I have not seen anything except their web site.
Due to the halachic complications that technological innovations have placed upon the Jewish consumer, the Star-K has been working with some manufacturers to design ovens that are more user friendly to the Jewish consumer (see appliance section for names of appliance manufacturers). Some of the common problems found in new ovens are twelve hour safety cut off, lights, icons and temperature displays that may be turned on by opening the oven door, and time bake features that must be manually turned off to silence the bell. In certified models, many of these features are disabled. (See appliance section for details of individual models.)
In addition, some Sabbath mode features such as temperature adjustment are quite practical and allow for easier use of the ovens on Yom Tov where the restrictions of cooking and burning are lifted when done under prescribed conditions. However, the Sabbath mode features do not in any way circumvent the regular restrictions involved in food preparations on Shabbos Kodesh.The laws of Bishul, Havarah, Shehiyah and Chazarah must still be observed even when using a Sabbath mode oven (see memo regarding oven use on Shabbos).
Please note that these are limited to the oven and do not apply to the use of the stovetop.
Torah observant Jews know that turning on the hot water faucet during Shabbos causes cold water to be heated, which transgresses the melacha of Bishul, cooking. What many don’t know is that even turning on what you think is cold water can also be a problem – if it’s a one-handled faucet.
Let’s first analyze why using hot water causes cold water to be heated. In a typical home setting, cold water arrives from the city supply under pressure. Turning on the hot water faucet allows this cold water into the hot water tank which, in turn, forces out the hot water already in the tank. Since the water in the tank is typically more than 120oF, the minimum temperature for bishul on Shabbos, the incoming cold water is immediately heated by the hot water that is already in the tank. 1
In a one-handled faucet, both hot and cold water are controlled by one handle. Generally, it works as follows: When turning on the faucet with the handle set in the middle position, there will be an even mixture of hot and cold water. As the handle is turned towards the right, a valve closes off the hot water and the water will be mostly cold; if the handle is pushed all the way toward the right, the water will be only cold. In this case, to avoid Shabbos transgressions, one would use the one-handled faucet with the handle turned towards the far-right position.2
Nevertheless, this handle poses a Shabbos challenge since one always has to remember to first push the handle lever towards the far right before turning on the faucet. This is not how it is normally done, as usually someone who wants cold water turns on the faucet with the handle facing the middle and then pushes it over to the right. Force of habit might cause one to do this on Shabbos. Also, a guest or child may not realize that this is an issue at all, and may unwittingly transgress the issur of bishul on Shabbos!3 An additional concern is that some one-handled faucets do not have a way of turning “all the way to the right.” They turn 360 degrees around and around. A person can easily misjudge where to turn the handle.
There are some one-handled faucets which have another problem, since by design they never shut off the hot water completely. This means that even when the handle is turned completely towards the right, some hot water still comes out.
Turn the hot water shutoff valve underneath the sink to the “off” position every erev Shabbos.5 This could also be done on Shabbos, as there is no melacha involved.
Install a two-handled faucet to avoid the problem.
If the hot water in the tank is less than 120oF, one would not be heating the cold water coming in. However, letting cold water in would be forbidden anyway since it activates the gas or electric heat.
Some one-handled faucets swivel from front to back and are functionally identical to faucets that swivel from side to side.
Older shutoff valves will not bear repeated turning week after week and may eventually leak. It is best to install a lever type control that turns off the water with a twist of 90 degrees. One can reroute the control so it is close to the opening of the under-sink doors, making it easy to reach.
It depends what you mean by grama. Assuming you mean grama with a time delay, than setting a timer such as a "shabbos clock" could be considered grama. Or using hot water from a faucet which causes cold water to take its place in a boiler and subsequently be boiled.
A Chabad rabbi told me that Chabad considers water filters which stay in place all the time an example of a "grama" with respect to Shabbos use (they allow their use Shabbos.)