Capacitor voltage ratings and voltage regulators

[sfr]

I usually use capactitors with a higher voltage rating than the circuit runs off of, "just in case" - I don't know how necessary it is, but my understanding is that it's good practice. 

Building the A/DA flanger, I ran into a few instances where my electro caps where all rated at 16V, which is what I normally use for 9V stompboxes.  The A/DA runs off of 15V coming out of the regulator.  I just ended up ordering new caps when I put in an order for a few parts, but I'm curious - when using a voltage regulator, using caps rated for a higher voltage than the circuit uses - is it a necessity/good idea? 

I really don't know why I started using higher rated caps - what sorts of failures cause an overvoltage situation that damage caps?

[petemoore]

I usually use capactitors with a higher voltage rating than the circuit runs off of, "just in case" - I don't know how necessary it is, but my understanding is that it's good practice.    Yes.

Building the A/DA flanger, I ran into a few instances where my electro caps where all rated at 16V, which is what I normally use for 9V stompboxes.  The A/DA runs off of 15V coming out of the regulator.  I just ended up ordering new caps when I put in an order for a few parts, but I'm curious - when using a voltage regulator, using caps rated for a higher voltage than the circuit uses - is it a necessity/good idea?  
  It is good to leave room for error, but as long as you don't overvoltage or reverse voltage polarized caps. For 15v supply I would use 25v - 50v, space permitting, there are some smaller devices available for tight spots or make room somehow.
I really don't know why I started using higher rated caps - what sorts of failures cause an overvoltage situation that damage caps?
  Applying too much voltage. Let's out the magic blue smoke, is messy/stinky.
  Reverse voltage, damages caps, makes them leaky, no longer as capacitative...lol...they won't hold a charge, may 'recover' and regrow with proper polarity and voltage over time...I don't like 'em, they're generally hard to change, and use reverse diode protection across the power supply to prevent any reverse voltages from being applied to the actives and caps.