On Sat, 29 Aug 2009 08:40:30 -0700, "Steve Lusardi"
wrote:

Bruce,
I'm confused. Just what statement did I make that was wrong? I did not state that any anything was unavailable. On the statement
you made, are you insinuating that class B GFI breakers trip slower than say class A GFI breakers in the case of imbalance? If you
are, that simply is incorrect. Breaker class refers to the overcurrent trip curve, not current imbalance between phase and
neutral. In all GFI breaker classes, imbalance trip is immediate without program delay. I cannot nor did I refer to any "CODE"
requirements... I simply do not know what rules you have to follow. As for the level of protection difference offered by imbalance
trip currents below 50 milliamps... it is effectively nil. As to your reference of false imbalance trips, in my experience, they
don't exist and if you have a device that causes these....get rid of it. It is unsafe. I have my whole house AND my machine shop
covered with one GFI breaker and I assure you it is very sensitive to the slightest current leakage and yet it successfully
supports 15 HP 3 phase motors. As an example I cannot use ANY inline AC line filters that connect to safety earth. Even the
slightest leakage current trips my main breaker.
Steve

You are in Germany apparently (.de URL) and they do things so
different over there as to almost eliminate common grounds for
discussion. I read the "International Codes and Devices" section in
the Pass & Seymour catalog, and it's... interesting. One of those
things that is totally natural if you grew up with it and understand
the logic, but it simply boggles the mind of an outsider.

You have Ring mains that cover the entire building with one big
circuit, fuses inside each receptacle and inside each cord cap on the
appliances, totally different rules on placement of devices in
bathrooms and near sinks...

And obviously, requirements to put the whole house main on a GFCI
and suffer through the inevitable nuisance trips. Over here, you only
put added protection on special-use circuits where it is necessary.

(To me, that's the "Green Acres" syndrome [1960's TV show] where the
lead characters are valiantly trying to go through life with a
hopelessly undersized rural electric system. Rationing their power
use with everything connected to a few recerptacles by cords, rather
than rip it out and start all over with sufficient circuits for their
needs.)

The Class A GFCI designation in the US only rates the sensitivity to
imbalance, where it trips at 2 to 3 MA imbalance line to return
(neutral). Class B GFCI is 20MA imbalance line to return, and only
available as a breaker to avoid accidental use where Class A is
required. The trip delay times are identical - on GFCI faults there
is no delay.

GFCI receptacles over here do not have any overload circuitry at
all. If it's a breaker, then there is a trip curve on the long-period
(thermal) overload section that can be altered for heavy motor
installations (and those breakers are special order only), but not on
the high-current (magnetic) section meant to clear short circuits.

I have had to kick things like decorative fountains with large
submersible pumps up to a Class B GFCI breaker solely because the
Class A would not hold in daily starts and stops with a timer. Every
time the pump kicked on, the capacitance of a few hundred feet of wire
to the pump coupled with the normal minor internal leakages in the
motor was just enough to trip it out.

-- Bruce --