On Fri, 28 Aug 2009 11:46:40 -0700, Bruce L. Bergman
wrote:

On Fri, 28 Aug 2009 18:45:38 -0700, "Steve Lusardi"
wrote:

A GFCI breaker is a good idea for the whole house. They compare the current out on the Phase lines with the return current on the
Neutral line. They are rated with the amount of imbalance they will tolerate before tripping. Please remember that 50 ma across
your heart is deadly, so the breaker should be for tolerance less than that. It is not necessary for all your breakers to be
ground fault capable, only one, the 100 amp main breaker. In that way, all service outlets and loads down stream will have this
protection. For clarity a 100 amp GFCI breaker rated at 30ma will trip under two conditions. One, when the 100 amp service is
exceeded or two, at any time an imbalance exceeding 30 ma exists. In the case of a fault, all breakers need to be manually
tripped. Then, reset the 100 amp GFCI breaker. After that, reset each breaker one at a time until the GFCI breaker trips again.
The circuit fed by that breaker will be the source of the ground fault. This process is then repeated with the individual loads on
that circuit until the main breaker trips again identifying the offending load.
Steve

WRONG. They do make Class B GFCI breakers, but those are meant for
equipment protection - they trip at 20 to 40 milliamps imbalance in
case the electric pump motor or the control panel is melting down, not
2 to 3 milliamps for personnel protection.

They make big GFCI units for building main breakers - 20A or much
larger (most let you set a potentiometer or a DIP switch to choose the
trip level) imbalance trip on a 1200A breaker. But that's to catch a
large fault in the building wiring - you could ground yourself and get
fried well-done and it wouldn't even care...

Then there are the Arc Fault Circuit Interruptors they now insist on
using on bedroom circuits - in theory a good idea if you get a nail
pinch in the walls, or a shorted extension cord or small appliance in
the bedrooms. In practice, it's just looking for an excuse to false
trip. The AFCI false trips, your alarm clock fails to go off, and you
are late for work. Do that a few times, and you won't have a job to
be late TO.

Consider the new rules of putting "all kitchen receptacles" on a
GFCI. You go off for a thhree week vacation, and the next day the
GFCI circuit that has your refrigerator and frezer on it nuisance
trips - something dumb like a drop of water got across the connection
block in the fridge, and then it evaporated. Nobody there to notice or
reset it.

When you come back in three weeks and open that refrigerator door,
you'd better not have just eaten. Unless you have an iron
constitution (or work in the sewers) one good lungfull and your
cookies are going to get tossed.

-- Bruce --
Fridge MUST be dedicated circuit by code - and does NOT need to be
gfci (being a motor - should not be GFCI)