Frank, note the cap rating should be 600VDC or 240VAC and should be
rated for "Across-The-Line". X10 recommends the Panasonic ECQ-U2A104MN.
This is a 0.1uf/250AC (-40C to +85C) metallized film cap. The package
size(mm) is 30.5L x 17.01H x 7.5W and the lead spacing is 26.5. It meets
the UL-1414 standard rated for "Across-The-Line". The Digi-Key part
number is P4603 and costs $1.22 in unit quantity. You can reach Digi-Key
at:

      http://www.digikey.com
      800-344-4539

   - Tom

At 02:10 PM 1/14/98 -0500, you wrote:
>Tom Handley wrote:
>>    Martin, there are commercial devices for this but the accepted DIY
>> method is a 0.1uf/600V cap across the 120V legs. Note, this is for the
>> X10's carrier frequency. For more info, check the comp.home.automation
>> news group and X10's site at:
>>
>>       http://www.x10.com
>>
>>    - Tom
>>
>One question: What type of cap? Ceramic, Monolithic, Poly?
>
>-Frank
>
>Frank Richterkessing
>
>FRANK.RICHTERKESSING@APPL.GE.COM
>
>