Siemens Safety Switches http://www.usa.siemens.com/switches http://sie.ag/1HLd7by: Siemens VBII safety switches provide superior performance and application flexibility. An extended array of accessories and replacement parts reduce installation costs.
Here is a documentary on how your HVAC condensing overflow shut-off device works. It's very common for a stopped-up drain to trigger this device and results in shutting off your AC/furnace. I am not a professional. This is for reference only. Here is how i replaced a condensate shut off switch: http://youtu.be/DXqXmz0YwQs If you want to buy this online, click on this link http://goo.gl/sFNaj