Re: [Phys-l] dielectric safety

[John Denker <jsd@av8n.com>]

On 04/01/2009 10:53 AM, David Strasburger-fac wrote:
> Students in a colleague's lab were pulling apart a defunct portable CD
> player today to get parts for another project. One student wanted to know
> if it was OK for him to cut open one of the capacitors to see what it
> looked like inside. The teacher said she wasn't sure and asked me if I
> knew if any of the materials inside were likely to be hazardous. I said I
> didn't know.
>
> I feel pretty confident about the safety measures we're taking to prevent
> electric shock, but could anyone on the list comment about the safety of
> cutting open a discharged capacitor salvaged from consumer electrincs?

Assume all capacitors (even small ones) manufactured before 1979 contain
PCBs.  PCBs are bad news.

Assume that the goo inside electrolytic capacitors is caustic.  Neutralize
it and dispose of it in accordance with standard chem-lab practices.

As for electrical safety:  for capacitors with appreciable energy content,
wire the terminals together and *leave* the wire in place until the
capacitor is well and truly disassembled.  Leaving the wire in place
defends against dielectric "memory" effects.