Cap voltage ratings - Can I do this?

[Gaz]

I was thinking about running a fan like in the diagram here:

http://www.blueglow.de/FenFan.html

It looks dead simple, but I'm elevating the heaters, and have a question about the cap's voltage rating. Must the cap be rated higher than the elevated voltage, or does it not matter since there is no ground reference?

I know the voltage across the cap would only be 8 volts or so, but I'm concerned I'm overlooking something...

Thanks.

[Firestorm]

The cap just has to be rated for the potential between the legs, so 10, 16, 25, whatever you have. Since you've already lifted the DC ground reference to do the elevation, you might want to use a bridge rectifier. Anywhere you put the fan to increase circulation will help, but it will work better if you can locate it to pull hot air out or push cool air in.