capacitor across main power switch

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as I understand it a cap across the main power switch reduces pitting arcing ect. I just completed a soft start (diy audio rev. 1) for my latest amp project. My question is would it be beneficial to add a cap across the relay contacts or would that be overkill? also worried about relay malfunctioning and burning up the resistor bank thinking of using a thermal switch to stop such a disaster any thoughts would be appreciated!!
 
From the second link...something to consider when contemplating a snubber...
*some contact materials require an arc to keep them free of sulfidation, oxidation, and contaminates. Such materials on contacts used in a dry or low-level circuit can result in the contacts failing electrically to close the circuit, even though they make physically. The contacts may look clean, but this is deceiving. In reality, there is a very thin film of insulating sulfidation, oxidation or contaminates on the surface of the contacts. This film must be removed for circuit continuity to be established, and arcing can accomplish this.* :)
 
more on cap across relay contacts

thanks for the replies! I will connect my scopemeter and see what the differential actually is. never considered that relay contacts may need a small arc to stay clean. Still worried about the relay failing and causing a fire, anyone have any ideas? I thought about a thermal limit switch (have a few from a server ups supply heat sink) but thinking that they cool off and switch back on. not the ideal situation. Should be something that switches open and stays that way, a neon indicator in parallel could signal the fault any ideas? thanks
 
A cap, or better still a cap in series with a low value resistor, reduces arcing when the contacts OPEN and break an inductive circuit that generates back EMF, caps won't do much for arcing due to a high current circuit being made, i.e. akin to arc welding.
 
Thanks again for your replies. digikeys thermal cutouts should work for the protection of the resistor banks with no worries! interesting design with the triac soft start if I had not already layed out and etched a board I probably would have went with that type of design. thanks again!!
 
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