Should We Laugh at the Jewish Light Switch?

There’s a light switch made specifically for observant Jews. What’s it like to use the KosherSwitch?

David Zvi Kalman
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The KosherSwitch arrives (traditional elements of the Sabbath experience not included).
The KosherSwitch arrives (traditional elements of the Sabbath experience not included).Credit: David Zvi Kalman
David Zvi Kalman

The light switch was born perfect. Few inventions can make this claim. So little have the switches changed that a switch made 100 years ago will work in a house built last week—and a switch made last week will work in a house built 100 years ago.

Attempts at improvement have failed; one cannot improve on perfection. Unless, of course, you’re intentionally trying to make an inferior product, in which case the sky (or the ground) is the limit. Introducing the KosherSwitch, a switch inferior to the original in every way but one: according to its inventors, it can be operated on Shabbat without violating the prohibition on using electricity.

Normally a light switch costs $2. I paid $45 back in May to be one of the first to receive a KosherSwitch. Last week it finally arrived.


This is the most nicely packaged loophole I have ever purchased. The fact that it has UL certification means it can be installed without worrying that it will burn down the house. Plus, the switch, it says, is “Endorsed by leading Orthodox Rabbis."

Let’s see what’s inside.

Inside the box

Reassuringly, it looks like a light switch. The construction looks solid. I still feel safe installing this.Credit: David Zvi Kalman

Reassuringly, it looks like a fairly generic light switch. The construction feels solid. I still feel safe installing this.

The switch looks fairly generic until one opens the tiny compartment on the bottom. Prying it open, I gain access to second, smaller switch with two options: "Normal" and "Sabbath."

Magic / More MagicCredit: David Zvi Kalman

In other words, how does one mark the transition from the six days of creation to the Sabbath? By flipping a switch.


The multitool turned out to be optional.Credit: David Zvi Kalman

Some Jewish rituals, like installing a mezuzah or constructing a sukkah, require Jews to be handy. Until the KosherSwitch, though, electrical work had never been a necessity of observance.

At this point I discovered that the switch wouldn’t work in most parts of my house, since it required a neutral wire, which older houses don’t always have and which normal light switches don’t need. I had wanted it to be a conversation piece for the living room, but it ended up in the bathroom instead, next to a GFCI outlet, which prevents people from getting electrocuted.

On the right, a device that might save your life. On the left, a device that might save your soul.Credit: David Zvi Kalman

The KosherSwitch in action

So, how does it work?

In “Normal” mode, the switch does what switches do. The End.

Switch it to “Sabbath” mode, though, and everything changes. By which I mean: a tiny green light turns on.

This is a good time to explain how “Sabbath" mode is supposed to work, according to the creators. When the green light is on, flipping the switch won’t do anything, since it’s not directly connected to any circuitry. It’s just a piece of plastic. Green means that it’s OK to flip the switch.

At random intervals, though, the light will turn red.

The red light means an internal sensor is checking whether the plastic switch is in the on or off position. When it finds out, it will turn the light on (or off).

But here's the twist: the sensor is designed to randomly malfunction. This means that it might take several green/red cycles before the KosherSwitch registers that I’ve flipped it.

These two types of randomness are ostensibly what make the KosherSwitch kosher. Supporters say that these random delays and malfunctions allow me to flip the switch and not be responsible for the consequences under Jewish law.

When the light is green, the creators say it’s OK to flip the switch.Credit: David Zvi Kalman

This isn’t the place to evaluate their argument. What I want to do is describe what it feels like to actually use the switch.

That’s so random

Sabbath mode creates random delays between flipping the switch and turning on the light. But random can mean many things: a truly random KosherSwitch might change in 20 seconds or not for a thousand years. I wanted to know: how random is the KosherSwitch?

The first random element is how long the light takes to cycle between green and red. Timing 10 cycles, I found that the light was green for 8 to 16 seconds, then red for 5 to 6 seconds. On average, the light was green for 11.6 seconds, then red for 5.7 seconds.

The second random element is the randomly malfunctioning sensor. To find out how often it malfunctioned, I flipped the switch and counted how many times the light turned red before the bathroom light turned on/off. After 21 incredibly boring trials, I found that on average the sensor worked on the third try. The sensor never malfunctioned more than five times in a row.

What does this all mean for the user? Imagine you’re leaving the bathroom. You check that the light is green, then flip the switch. Nothing will happen for at least five seconds, which is normally how long it takes for a switch to work. On average, it will take 45 seconds for the light to go off, and it will almost certainly be off before two minutes are up.

Why is this light different from all other lights?

The red light is on: No, can't do that on Shabbat.Credit: David Zvi Kalman

Are these intervals random? Yes — but they’re random within some pretty specific bounds. If the light was red for 10 minutes, or if the switch took an hour to register a change, you wouldn’t want it. Perhaps it's random from a Jewish legal perspective. From the user’s perspective, the switch’s behavior is very predictable.

That being said: the KosherSwitch still doesn’t feel like a normal switch, mainly because it’s worse. Normal switches are basically instantaneous; the KosherSwitch’s five-second minimum is an eternity by comparison. Normal switches can be operated almost unconsciously; to operate the KosherSwitch, I need to stare at a little green light.

These differences seem small, but in comparison to the elegant simplicity of the ordinary switch, the KosherSwitch comes across as weird and awkward — which, I think, is exactly what its creators wanted, because these “features” set the KosherSwitch clearly apart from ordinary switches without making it obnoxious to use. Its oddities are a pretty strong reminder that today is a little different.

Ultimately, I probably wouldn't use the KosherSwitch on Shabbat — for me, it’s not worth entering into religious debate for such a minor benefit. But that doesn’t take away from my admiration for the engineers, who have created not just a professional-looking product, but a carefully calibrated experience that attempts to create for its users a unique (though entirely artificial) sense of Shabbat’s difference.

The light switch was an early manifestation of a desire for easy living that keeps leading us to integrate electronics ever more deeply into our lives. The friction between that trend and Shabbat observance will only grow in the years to come. This device doesn’t solve this problem, but its design principles might point the way towards a solution down the road. The KosherSwitch is less than perfection—but it’s also more than a joke.

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