Electronic – Pull Switches – why so expensive

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I would like to use a pull switch as a trigger for an alarm that I'm building. When the switch is triggered it will turn on a siren and potentially a strobe light. I've found plenty of options out there, but the prices are a bit staggering.

Take this one for example, it's $238. I was thinking $20 would be expensive! My alarm isn't going to be used in an industrial environment and the items I'm securing aren't worth enough to justify spending that kind of money for a switch.

I think a simple pull type light switch would be sufficient, but I need the cable to break away from the switch when activated and not damage it in the process.

I guess I have two questions:

  1. Why is this switch so expensive?
  2. What other options are there for a N.O. pull cable switch that stays closed after being activated? I'm open to ideas of building my own switch.

Best Answer

Why is this switch so expensive?

  • The switch you reference is made to be used as an emergency stop via a length of pull cord (think of a stop-request cord on a transit bus ). It is made to latch open once pulled (i.e. it's a mechanical one-shot). It is more than a simple pull switch.
  • It is rated IP67, which equates to dustproof and immersion proof. It is made for demanding industrial applications including washdown and nontrivial shock and vibration.
  • It is a safety device made by a name brand company.

What other options are there for a NO pull cable switch? I'm open to ideas of building my own switch.

Many switches can be used as a pull switch depending on the specifics of your application. Something as simple as this can have a string tied to it such that the switch actuates when the string is pulled.

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If you need the cable to break away from the switch, there are plenty of mechanical ways to accomplish this. A breakaway lanyard is made to open at a certain tension. There are also more repeatable "tension fuse" type devices based on magnets for various applications; take a look through a big industrial catalog for ideas.

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