Class 1 Div 2 On/Off Switch Question

[jeffc0987]

I was hoping someone could shed a bit of light on switch selection when trying to design a system for a class 1 div. 2 system.

Our initial attempt at getting certified received this response regarding the switch and a potentiometer we plan to use in our system.

Control/Battery Enclosure

We are using a rain proof, vented battery enclosure

Tool Removable Cover - The sample we submitted for review was constructed with a potentiometer located inside the enclosure. They said that no addition evaluation will be required as a sparking part if the cover requires a tool to open.

On/Off Switch
A switch is considered to be a sparking part and will need to be evaluated in the final investigation.

Considering we put the On/Off switch inside the tool removable cover, and it is a sparking part similar to a potentiometer, it seems reasonable to assume that having a Tool Removable Cover will prevent us from having to get a certified switch. I have noticed that one of our competitors websites does however list that they use a Class 1 Div. 1 switch.

The reason this was separated in our response was because our original demo we sent to them did not include an On/Off switch (I don't have any reasoning as to why this is the case, I am taking over this project from an older employee). If anyone is a bit more savvy dealing with Class 1 Div. 2 systems any advice would be appreciated.

 

[DRWeig]

Is this for compliance with UL or another standard? Which one? The rules in the standard should be pretty explicit.

How much current does the switch control, and at what voltage? What is the normal voltage and current through the potentiometer?

For example, if the potentiometer is 10 kΩ and the source voltage is 24 VDC, it may be only capable of releasing ignition-level energy if it has failed or if or a fault exists (abnormal operation). Meanwhile, if your switch is turning on and off the 120 VAC circuit that feeds the device, it may release ignition-level energy every time it is opened under load (in normal operation).

My example is based on a wild guess about your product. We need a lot more detail about your design parameters and the relevant standard(s) before we can provide real opinions.



Good on ya,

Goober Dave

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