I bought one of those 3 neon bulb testers to check the wiring of a new
house some friends of mine bought. In one room, all of the outlets read
Open Ground. But there is one outlet in the room which will read
Hot/Neutral Reverse when it has an appliance (with a 3 prong plug) in
it. Otherwise it also reads Open Ground. It will also read Hot/Neutral
reverse when the GFCI test button is depressed. Any ideas?
If by new house, you mean new construction, I'd get the builder to fix
it. If not, then you can either fix it yourself if you have the skills
or hire an electrician. Sounds like you already know what you have.
One outlet with hot/neutral reversed and no ground coming to any of the
outlets, which likely means an unfastened ground path in the feed from
the circuit breaker to the first outlet in the chain.
Could be the appliance has some leakage current back into the open ground.
Do all 3 neon bulbs light up?
I believe the GFCI test button just connects hot to ground via a resistor.
since the ground is open, your GFCI tester is energizing the ground wire
with a small amount of current (limited by the resistor) just enough to
light up the red neon bulb which is also connected between neutral and
I assume your circuit is working other than the open ground but if you have
an open neutral then those 3 neon light testers will not work (they give
wrong indications), but nothing else plugged into the circuit works either.
Note when you have an open ground and you have a 3 neon light tester plugged
into an outlet, you can be shocked! That is if you are grounded and touch
any metal which is connected to the open ground circuit such as a metal
electical box or metal case of an appliance . It's not alot of current, but
enough to give you a scare BTDT.
Which country are you in?
The hot/neutral is easy to fix - just turn the power off, unscrew the
socket plate from the wall, swap the hot and neutral connections over
and put it all back.
The open ground is not so easy. You could check for loose connections
on the ground wire or replace the cable from the socket back to the
As Kevin Ricks said the reversal can because the "appliance has some
leakage current back into the open ground". If the outlet doesn't have a
ground the tester can't reliably measure "normal" or "reversed" connections.
One way to detect if a wire is "hot" is to use a 2 lead neon test light.
Touch one lead (body contact) and touch the other lead to the
wire/termanal to be tested - if "hot" the neon light will light dimly
(you probably need to minimize outside light to see it). The current
through a neon light tester is very low at 120 volts, and even lower if
the body isn't grounded and there are only capacitive currents. But
since I am touching one lead I am real careful what testers I use.
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