modified GFCI

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Re: modified GFCI

Post by JR. » Tue May 01, 2018 11:51 am

Perhaps of interest is an outlet tester that supports identifying energized safety ground. Clever (perhaps) they use the voltage potential between an energized safety ground and a front panel touch contact (hmmmm that looks familiar :roll: ) to switch on a simple LCD display warning. The 3 lights look identical to the common 3 lamp tester that is fooled by RPBG (reverse polarity bootleg ground), but the extra ground test "should" reveal a hot safety ground.

I have questions about the ability of this to pass a 100M @ 500V insulation test like mine does, but guess what? They are not UL listed. :roll: The critical question is will a LCD control lines shrug off 500V without breaking down?

Oddly they put a CE mark on the front panel of a domestic made 120V only SKU that is only sold in the US. I guess this is yet another IQ test for an ignorant public. I sent an email to the manufacturer but surprise-surprise I did not get a response. :lol:

Coincidentally I just bought a chinese 12V 6A PS with CE mark and no UL, so I failed that test too. :oops: At least the chinese PS is universal mains voltage .

Just for chuckles I cobbled a neon lamp with series resistor to a cheap 3 lamp tester to see if I could see hot safety grounds by illuminating the neon bulb.
The picture shows the cheap 3 lamp tester indicating "all good" when plugged into an intentionally miswired outlet (RPBG). The neon lamp, just above and to the right of my finger is visible (just barely) in a dim room when I touch it, so not a robust real world solution. I momentarily considered adding some light amplification but this extra complexity defeats the simplicity. So my already published design still looks good... I really prefer having a red light indicate dangerous ground, with green lights for good.


PS: There is an old joke that a man with a voltmeter knows his voltage, but with two VOMs you never know which voltage is right. I tried to measure the wimpy current that was barely lighting my neon bulb. Since I now own 3 VOMs I figured we could take a vote. :lol: The bad news is I'm not sure I trust any of the readings. My presumably respectable (Fluke 107), indicates over 100mA of AC current in series with my finger touch. My very old mostly retired rat shack VOM indicates something like 26 uA. Finally my cheap no-name VOM indicates 0.0. Of those three I suspect the old ratshack's 26uA is closer to the truth, than >100mA indicated through a barely illuminated neon bulb.

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Re: modified GFCI

Post by mediatechnology » Tue May 01, 2018 1:30 pm

Wow, looks familiar.
Reminds me of the patent on the input-capacitorless preamp granted to someone else 5 years after I first published it.
You suppose they read us here?

From the ads at the bottom of the page I see these people are into emf and "Groundology."

Some research:

When you connect these to third wire ground you really, really, really want to make sure that ground is ground.

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Re: modified GFCI

Post by JR. » Tue May 01, 2018 3:20 pm

I pretty much tried to whistle past the rest of that website based on things they sell...

An outlet tester that actually detects RPBG is a good thing if it doesn't kill the users first. :o


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