b*******y
发帖数: 30 | 1 Sorry, can't type chinese at work.
i have 3 outlets in 2 bathrooms, one of them is GFCI. problem is that one of
the rest two non-GFCI is not working (NO GFCI tripped), tested as 'open
neutral'(120v btwn hot and ground, while 0 btwn hot and neutral). Futher
checked for all the wiring and made sure good contact everywhere.
assume the two non-GFCI's are wired on GFCI's downstream (by code for
mutiple GFCI protection), how can one be good and one be bad?
Any input? what could be problem and how shall I diagonse? thanks, | G***s
发帖数: 10030 | | b*******y
发帖数: 30 | 3 again, sorry for not typing in zhong wen,
simply put, GFCI is the one with two buttens on it and it will cut off the
power at fault. | w******t
发帖数: 16937 | 4 科普来了：
That outlet is called a ground-fault circuit interrupter (GFCI). It's there
to protect people from electrical shock, so it is completely different from
a fuse.
The question on appliance plugs talks about fuses. The idea behind a fuse is
to protect a house from an electrical fire. If the hot wire were to
accidentally touch the neutral wire for some reason (say, because a mouse
chews through the insulation, or someone drives a- nail through the wire
while hanging a picture, or the vacuum cleaner sucks up an outlet cord and
cuts it), an incredible amount of current will flow through the circuit and
start heating it up like one of the coils in a toaster. The fuse heats up
faster than the wire and burns out before the wire can start a fire.
A GFCI is much more subtle. When you look at a normal 120-volt outlet in the
United States, there are two vertical slots and then a round hole centered
below them. The left slot is slightly larger than the right. The left slot
is called "neutral," the right slot is called "hot" and the hole below them
is called "ground." If an appliance is working properly, all electricity
that the appliance uses will flow from hot to neutral. A GFCI monitors the
amount of current flowing from hot to neutral. If there is any imbalance, it
trips the circuit. It is able to sense a mismatch as small as 4 or 5
milliamps, and it can react as quickly as one-thirtieth of a second.
So let's say you are outside with your power drill and it is raining. You
are standing on the ground, and since the drill is wet there is a path from
the hot wire inside the drill through you to ground (see How Power
Distribution Grids Work for details on grounding). If electricity flows from
hot to ground through you, it could be fatal. The GFCI can sense the
current flowing through you because not all of the current is flowing from
hot to neutral as it expects -- some of it is flowing through you to ground.
As soon as the GFCI senses that, it trips the circuit and cuts off the
electricity.
【在 G***s 的大作中提到】
: 求科普GFCI
| b*******y
发帖数: 30 | |
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