I was thinking that a powerful set of electromagnets in high risk doorways could be used to stop active shooters. By placing them in doorways. The magnet size could be mitigated. Also, they could be activated situationally to mitigate collateral damage. How practical is this idea? I know it would take a hefty amount of steel and copper but it it was less than 100k wouldn’t that be worth it? Combine that with an automatic detection system and it would definitely make it harder for the shooters to hurt people. I’m fully aware that non-magnetic weapons are on the market

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    $\begingroup$ Unlikely if military facilities don't use them. What stops the shooter from shooting the door first? I also think you underestimate the size of the magnet. Also, I don't think your regular 120V utility is going to be able to run the magnet and I don't think schools have an industrial utility available. You also say doorways (plural) but then talk about the cost as if there was just one door. Note that such a magnet should be considered a deadly device and would likely damage everything ferrous around it when turned on (like the building itself). IMO you might as well have trip mines. Cheaper. $\endgroup$
    – DKNguyen
    Jun 4 at 7:31
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    $\begingroup$ Having recently had a scan in an mri machine, given the size of that how big will your proposed device be? $\endgroup$
    – Solar Mike
    Jun 4 at 8:22
  • $\begingroup$ "... a powerful set of electromagnets in high risk doorways could be used to stop active shooters." Stop them how? Pull the guns out of their hands as they walk through the doorway? What about the keys in my pocket or my artificial hip joint? $\endgroup$
    – Transistor
    Jun 4 at 22:07
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    $\begingroup$ I'm having trouble deciding if your idea is to keep the door from opening, or pull the weapon out of his hand, or what? $\endgroup$
    – RC_23
    Jun 4 at 22:47
  • $\begingroup$ I’m voting to close this question because it's beyond ridiculous $\endgroup$ Jun 6 at 13:39

1 Answer 1


How practical is this idea? Not practical at all.

First, we'll start with doing it even if it were free. You can't turn this monster magnet on until the event happens. We aren't going to de-magnetize every crdit card of every person who enters a school. A shooter who enters a room then starts shooting isn't deterred at all. Second, once it's turned on, no armed response can occur.

Second, we'll deal with the practicality of such an installation. We will need power, and a lot of it. So probably we now need 480V or 2300V feeds. I doubt schools in the US (no other nation seems to need this anyway) have lighting on anything other than 120V except in the stadium, which are likely no more tham 240V. Getting high voltage into the building means new power drops and distribution systems. Now we need to install these things. How many do we need? Every classroom door? So the shooter will just shoot through doors anstead of walking through them?

The whole things seems like massively wasted resources for minimal gain. My suggestion is that this will be solved politically, not through engineering, and recent history has shown that there is zero political will to tackle the actual issue.


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