Other problems required more complicated solutions. How can doctors, nurses and others who must work on the Sabbath take notes but not break the law against writing on the Sabbath? A pen with disappearing ink. Because the notes are not permanent it is not considered writing under Jewish law.
The institute's 23 staff members spend much of their time responding to callers from Israel, the United States and around the world who have questions about what type of fish is kosher, where they can buy a Sabbath-friendly telephone or how Jewish law applies to in vitro fertilization and organ transplants.
Lately, institute staff members worked overtime before the Jewish high holidays, starting with Rosh Hashana -- the Jewish new year -- which began Friday. Many Jews, Orthodox and secular, develop a heightened interest in Jewish law and traditions around the holidays, staff members say.
The question posed by Israel's electric company is one of the rare cases in which the institute does not have a solution on file. On the Sabbath -- from sundown Friday to sundown Saturday -- some electric company employees must tend the coal-fired power plants. But many members of the ultra-Orthodox Jewish community believe the state-run corporation should not break Sabbath rules. To distance themselves from the power company, some ultra-Orthodox communities such as Mea Shearim in Jerusalem and Modiin Illit in the West Bank have broken away from the national power grid, using private generators on the Sabbath.
But the Israel Electric Corp. is looking to win these customers back, searching for a way to produce power on the Sabbath within the guidelines of Jewish law.
"We operate the power stations so the number of workers is kept to a minimum. But there are certain members of the ultra-Orthodox community that don't accept it, and that's why we are looking for solutions," said David Golan, a spokesman for the utility.
Halperin is looking for ways to automate the work on the Sabbath. He hasn't found an answer yet, but says he is confident that one will be found that will satisfy electricity producers and Jews who adhere strictly to Jewish law.
A minority in Israel strictly observes all the Jewish laws studied at the institute. Many Israelis drive on the Sabbath and never worry about eating kosher. Still, the Israeli government, which helps fund the institute, says that secular Jews take an interest in observing certain Jewish laws.
"There is a large movement of people coming back to roots and religious observance, and they are looking for traditions, and the institute is where they can come for guidance in those traditions," said Yitzhak Cohen, Israel's minister in charge of religious councils.
Searching for loopholes in Jewish law might appear to be little more than theological hairsplitting. But institute staff members say their goal is not to find ways to circumvent divine laws so that Jews can watch television or drive on a day meant for family, quiet and prayer.
"We are not here to eradicate the Sabbath," said Rabbi Shmuel Strauss, who teaches the applications of Jewish law at schools and public seminars.
"If the loophole is there, it is there to be used in a situation of need," he said.
When Israel's first astronaut, Illan Ramon -- a member of the Columbia crew who died when the shuttle broke apart on re-entry in 2003 -- went to space, he wanted to know when to observe the Sabbath. Because he was orbiting Earth so quickly, sunset and sunrise occurred about every 90 minutes. Halperin told him he should observe the Sabbath during the hours when it would occur at the launching pad.
For an organization that boasts of offering high-tech guidance on the use of satellites, submarines and medical equipment, the institute itself is decidedly low-tech, a warren of musty offices in a decrepit stone building in Jerusalem.
On a recent morning, an engineer with a white beard worked in a tiny room with vise grips, electrical plugs and other materials. Nearby, a secretary filed decisions and queries in folders stacked from floor to ceiling. Down the hall, a group of Talmudic scholars with beards and black caps sat hunched over Hebrew texts, exploring Jewish law as it applies to medical issues.
At the far end of the building is the drab office of Halperin, who founded the institute in 1965 and remains its guiding force.
A tall man in a black suit coat, black pants and black hat, Halperin sat behind a desk littered with paperwork, answering calls on his cell phone with one hand while scribbling notes with the other.
That morning, he had received a query from an Israeli hospital about a food warmer used on the Sabbath. Could it be used to warm both dairy and meat dishes, which must remain separate? In this case, Halperin ruled that it could.
He received a query from an Israeli woman with muscular dystrophy who used a mechanized wheelchair to get in and out of bed. Would she be able to use the wheelchair on the Sabbath? Yes, he told her; his engineers and scholars would help her find a solution.
"Every moment there is something new," Halperin said.