# Machine saftey category 3



## Peewee0413 (Oct 18, 2012)

Do you know anything about machine safety?

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## Peewee0413 (Oct 18, 2012)

Probably need to read up on all the categories. The company probably uses 3 as a target, and wants to know you understand stuff like safety relays or redundancies. 

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## gpop (May 14, 2018)

https://machinerysafety101.com/2011/09/19/category-3-architecture/


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## accurateproelectric (Jun 30, 2019)

Yes, I was aware of machine safety but was not aware of categories. 
so far what I dig out. is...

CATEGORY 1: “A single fault can lead to the loss of safety function.”
Example: A door switch contact failing in the closed position resulting in the machine continuing to run
CATEGORY 2: “A single fault can lead to the loss of safety function and the loss of safety function shall be detected.”
Example: A door switch contact failing in the closed position resulting in the machine continuing to run but a second door switch triggers a warning light.
CATEGORY 3: “A single fault does not lead to the loss of safety function.”
Example: a door switch contact failing in the closed position but a second door switch alerts a safe controller which shuts down the machine. The distinguishing detail from Category 4 is that there can be multiple switches used on each channel of the controller.
CATEGORY 4: “An accumulation of safety faults does not lead to the loss of safety function.”
still digging out more...


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## joebanana (Dec 21, 2010)

What category is "spontaneous, rapid, self disassembly"?


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