Reverse Polarity in Two Hole Outlet

(John Allingham) #1

How do you guys test for reverse polarity in a house with two hole outlets?
Cut the ground pin off your tester?

(Marc D. Shunk) #2

With a non-contact voltage probe. Some people call it a "tic tracer". The wider slot is neutral, and the narrower slot should be the hot. The ticker should only light up in the shorter slot. I know some guys simply use one of those 3-prong to 2-prong adaptors on their regular receptacle tester.

If you run across any old receptacles where both slots are the same height, or where both slots are "T" shaped, I would recommend you call them out as recognized hazards. Put no special effort into determining the polarity of receptacles of this type.

(David C. Macy, CMI) #3

Could you please enlighten me on these type of receptacles as to why and if you have a photo would be nice.

(Marcel Gratton, CMI) #4

I have a Sure test tester with a retractable ground pin...

(Justin D. Schlueter) #5

He's talking about a receptacle like this:

One of the reasons that I think that they are scary is that they could be wired for 120 or 240 volts. In other words, you could have one of these receptacles wired to 240 volt circuit. (and be able to plug in 120 volt appliances)

(Bob Elliott, 450.0002662) #6

good point

(Marc D. Shunk) #7

At least the one in your pic is polarized. They often aren't.

(John Kogel) #8

With a 2-prong adaptor, these little testers tell you if there is power, but don’t tell you polarity if there’s no ground. OK for testing old razor outlets, there is no polarity concern with those, isolation transformer. The old outlets like the one in the middle are not polarized and ought to be replaced.

John Kogel


Two-prong x3.jpg

(Marcel Gratton, CMI) #9

Attached is a few pics of receptacles/plugs.

(John Allingham) #10

Thanks gents. :)

(Ralph Brady) #11

As was stated already, the 3 prong testers do not work without a ground connection. You need to use one of these (or equivalent) to test for reverse polarity on all open ground 3-prong receptacles and all 2-prong receptacles. I like the fluke model, however I have not tried the new/current version that fluke is selling.


(Frank L. Bartlo) #12

I just use my hand as the electrode by holding a probe tester with one probe on my hand and sticking the other probe in the slot. The hot slot will cause it to light up just a little bit -- barely noticably, but visibly.

Sometimes I shake my hand as if shocked as a practical joke ... sometimes making a "home inspector jackass" joke. :D

(Marc D. Shunk) #13

You're an idiot.

(Frank L. Bartlo) #14

Probe tester. I don't even so much as get a shock, but it is sometimes difficult to see the indicator light up.

But I'll test that 2-prong adaper idea. Never occurred to me that would work.

As I thought, it doesn't work: just shows as an open ground either correctly or incorrectly polarized.

(Chuck Evans, CMI TREC 7657) #15

double post

(Chuck Evans, CMI TREC 7657) #16

Old thread, but I thought I would pass along the method I use to check polarity on a two prong outlet. All that is needed is a two prong neon tester and a non-contact voltage detector/ticker.

Just plug in the tester and use the detector to confirm that the wire to the narrow slot is the hot one (won't work on the "T" shaped slots where they are the same size).

(Larry Kage, CMI) #17

Using one of these “tic tracers” works good. Just stick it in the small slot to check for voltage.

(Michael Roberson) #18

never tried this, its best on video.

(Leigh Goodman) #19

I do it the way Frank does it

(Lion Ho) #20

Hi…In case you didn’t know, reverse polarity at a 120 V outlet is not HOT to GROUND, and its a far cry from wiring a 240V outlet HOT to GROUND. You are comparing apples to oranges.
Your initial comment about contacting the company that did the wiring, and that it was probably done by a newbie, or helper was spot on by the way.