Re: Capacitor to bypass GFI outlet?

["Dennis Brothers" <mysurname@xxxxxxxxxxxx>]

"Chris Shearer Cooper" <chrisnews@xxxxxxx> wrote in message
news:11rdc4ulchilk45@xxxxxxxxxxxxxxxxxxxxx
> The official word from X10 Customer Support is that one way to get the
> X-10 signals to hop from one phase to another is by "installing a 0.1
> microfarad, 600VDC capacitor across the two phases in the panel, i.e. by
> connecting the capacitor across any 220V breaker."
>
> Can a similar trick be used to get the signal across a GFI outlet?  That
> is, what would happen if I attached a 0.1 uF 600V cap from the line to the
> load?
> Would the X-10 signal get through?
> Would it affect the ability of the GFI outlet to detect ground faults?

The reactance of the cap is 1 / (2 * Pi * f * C), or roughly 1 / (400 * C)
at 60 Hz, so it has a reactance of approximately 25K ohms.  If you assume
the current sense circuit in the GFCI drops one volt (I have no idea how
good an assumption this is, but you could measure it), the cap would put 40
microamps of unbalanced current into the load circuit (or looked at another
way, it would "steal" 40 uA from the hot-side current sensor).  Dunno if
that's enought to trip the interrupter, but it's a pretty easy experiment to
try.

I haven't really looked at GFCIs, but isn't it a four-terminal device? I
would guess so, since it needs to monitor current on the neutral as well as
the hot side.  If that's the case, put an identical cap across the neutral
side as well, and things will be back in balance.

    - Dennis Brothers