GFCI Tester

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#1

Originally Posted By: apightling
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For those who might want to roll their own GFCI tester. . . . the following has worked for me:


Parts:

Clamshell 120VAC plug
Door bell push button that fits in the end of the receptacle without touching other conductors.
100K 1/2W resistor
25K 1/2W resistor . . . change this to 5K 1/2W per next post. . .

The door bell button goes where the electrical wire would have gone if it was used. . . . in the end of the clamshell plug opposite the prongs. . . you might have to trim some plastic.
Install the 100K in the receptacle from hot to neutral at the screw terminals of the plug. Connect the 5K from hot (blk, gold) to one side of the door bell switch. Connect the other side of the door bell switch to the ground connection in the plug.

Screw the assy together such that nothing is touching. . . yes it is a pain if your leads are too long. . . . rem: you can't cut em longer. . . .

Get out your handy Ohm meter. You should read 100KOhms from hot to neutral. You should read infinite from hot or neutral to ground.
When the button is pressed you should read 100K from hot to neutral, 105K from neutral to ground, and 5K from hot to ground. If you get these readings or something very close to them go to the next step. If not, find out where you miswired and fix it, and start this step over.

Plug your assy into a GFCI outlet. . .. nothing should happen . . . the 100K is dissipating about 0.144W so even enclosed in the plug it should last a long time if you left it plugged in . . . you wouldn't but . . . . if you did . . . . . . push the button . . . the GFCI should trip right away. Release the button and reset the GFCI . . . try it again . . . it works . . good . . .

Plugging the assy into a non GFCI outlet doesn't do much unless you have GFCI breakers on it . . . I haven't checked a GFCI breaker but the assy should trip them just fine . . .

Yeah, I know it should be approved by someone or other before use . . . I R an engineer . . . does that count? . . . 'never let the train run off the track while I was driving . . . . at any rate, no warranty for specific use is expressed or implied and if you build it you accept all responsibility for its use. . . . by whomever might use it now, in the future, or the past if time travel is invented.

If something needs more explanation please post here. . . if you have a question others probably do too . . .

-ap

#2

Originally Posted By: apightling
This post was automatically imported from our archived forum.


. . . . all proud of my new GFCI tester widget I went next door to test theirs . . . . it didn’t work . . . my GFCI outlets tripped fine and dandy but not so next door . when I returned mine still tripped . . the hot to ground resistor needs to be 5K vice 25K for my next door neighbors GFCI outlets to trip . . . change the parts list accordingly . . .


Some GFCIs trip at very low current . . . others need more . . . I like mine better . . .

However, referring to a previous thread wherein motors and inductors were demonstrated as able to trip GFCI outlets . . . I may have a more sensitive model so, as always, your experience may be different. . .


-ap

#3

Originally Posted By: roconnor
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It is actually recommended by receptacle manufacturer’s (e.g Leviton) and many industry experts (search Mike Holt’s board) to test GFCI receptacles by pushing the test button built into the devices.


Either that, or a good $20 receptacle tester like the GB Surewire (or the higher end ... ahem ... SureTest) for upstream receptacles and you are good to go ... as long as you are aware of the potential hazards and complications associated with pushing that receptacle tester button ... ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif)

--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

#4

Originally Posted By: apightling
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I understand the mfg wanted us to use their device to test their device. . . . that strikes me as the wolf guarding the chicken coop . . . you are dependent on a piece of test equipment that is not in your control . . . . . . you are right . . . it costs less to buy the tester than to make one . . . time and materials considered . .


-ap

#5

Originally Posted By: mtimpani
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icon_eek.gif

–
Thank you, MarkTimpani


www.pridepropertyinspections.com
#6

Originally Posted By: rdawes
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If the outlet has an open ground then your tester, or for that matter, any external GFCI tester (including my expensive Suretest) will not trip the GFCI. The self test in the GFCI will trip it as it does not require a ground connection to perform the test. That’s why GFCIs can still be used effectively on old 2 wire circuits.

#7

Originally Posted By: jpope
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I can see the client now - I pull out this home made thing wrapped in duct tape and stick it into a receptacle. Then I try and convince everybody that the GFCI is defective because it didn’t trip when I pushed my doorbell button. . . eusa_doh.gif


I think it would be better received if I told the client that I had married my sister who, by the way, is also my cousin.

--
Jeff Pope
JPI Home Inspection Service
"At JPI, we'll help you look better"
(661) 212-0738

#8

Originally Posted By: lkage
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jpope wrote:
I can see the client now - I pull out this home made thing wrapped in duct tape and stick it into a receptacle. Then I try and convince everybody that the GFCI is defective because it didn't trip when I pushed my doorbell button. . . ![eusa_doh.gif](upload://has2a0g32D0AAlDjAwVcrg3HnhX.gif)

I think it would be better received if I told the client that I had married my sister who, by the way, is also my cousin.


I'm going to stick to the correct tool and person for the job.

--
"I have never met a man so ignorant that I couldn't learn something from him."
Galileo Galilei
#9

Originally Posted By: dedwards
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delete

#10

Originally Posted By: rbennett
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Jpope


An ohm meter is an ohm meter do not BS me or my friends

Do not get screwed

I do a gree that "eye candy is part of our show" but remember that a moisture meter is only a $10.00 item from radio shack packaged so that it displayes % of moisture

Don't get ripted off by saying that a door button and duck tape are not of the quality of a "belesed of test equipment

I have used an DVM and a "heat gun" load to test for voltage drop
Yes it takes some time but the math does not change

Ohms law is Ohms law

GHCI are a joke anyway -- Try to trip one with your fingers and a couple of paper clips between the hot and the nutral (no don't I want you around for some time so I can continue to educate your)

Now you see why a distrubuiton box must be wired the way that it is.

Nutrials in one area and grounds in another

That is unless your are trying to bet the system

Back to elect 101 or ask Joe T

Bottom line their is nothing wrong with home made test equipment

I know that you did not say so but you shure made your point

How about micro wave oven leakage testers --- another radio shack toy that they know longer sell of $19.00 --You could build one for $20.00

Oh yes, a water pressure meter mady with a tire gage and a short garden hose and a weed killer container with an air fitting on it ??? -- cost nothing

Hey no offence

Some of us must live by our witts - we don't have all thoughts $2000.00 inspections to do every day

Thus - got to think out of the box

I too give my best to the home made 'test Box"

#11

Originally Posted By: dedwards
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icon_eek.gif

#12

Originally Posted By: jpope
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Thanks for the education Richard, but I’ll stick to my UL listed devices for testing circuits, GFCI’s and AFCI’s.


I will be less likely to be found liable for damages caused by specialized equipment manufactured for a specific purpose.

--
Jeff Pope
JPI Home Inspection Service
"At JPI, we'll help you look better"
(661) 212-0738

#13

Originally Posted By: rbennett
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Point well taken


Remember a good DVM, clamp on amp meter etc. are all good basic test equipment

I just don't like "test equipment company" ripping me off for something that is nothing but "eye candy"

Yes in some cases it it a better idea to buy the new toy because they do the math inside and it looks good to the client

But don't get taken to the cleaners for a VOM meter

Have a great day


RLB

#14

Originally Posted By: roconnor
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Using manufactured listed equipment and meters is very different from using a home made electrical device, and I agree there could be hazards and additional liability associated with that. Also consider the additional time needed to take all those measurements as compared to simply plugging in a standard tester.


I would go with a UL approved $20 plug in GFCI receptacle tester before I even thought about wiring up anything myself.

--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

#15

Originally Posted By: apightling
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random thoughts . . . I agree . . . a test device that is recognized as a reliable indicator of something or other is a good thing . . . . . .


I also agree a $20 GFCI tester is a solid buy compared to building one. BTW, what's the UL listing on the comml tester?

When you push the button the GFCI will pop . . . will we know why? Maybe we don't care . . .

when the manufacurer of a device tells me to use the device to test the device . . . another home made detector goes off in my mind . . .

Paper clips from hot to ground would do the trick too . . .

and no electrical tape was used on my tester . . . it is a yellow plug that complements the polarity checker . . . 'looks a lot like the other yellow test equipment I have . . .

'must admit . . . there's a bit of duct tape on my Simpson 260 . . . but I don't use that much any more. . .

My motivation was to understand why GFCI outlets tripped when a reactive load was presented to them . . . I found out my GFCI outlets are more sensitive than the several I have checked since . . .

I would rather understand why and how something works and then select a test device appropriate to the task . . . sometimes the task is part technical and part marketing . . . and the blinking leds and digital meters are important . . .

great responses all . . . thanks

-ap

#16

Originally Posted By: jwortham
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Someone has WAYYYY too much time on their hands…

#17

Originally Posted By: phinsperger
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apightling wrote:

My motivation was to understand why GFCI outlets tripped when a reactive load was presented to them . . . I would rather understand why and how something works...


And for that you should be commended. Seeking knowlegde is never a waste of time.

--
.


Paul Hinsperger
Hinsperger Inspection Services
Chairman - NACHI Awards Committee
Place your Award Nominations
here !
#18

Originally Posted By: roconnor
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apightling wrote:
BTW, what's the UL listing on the comml tester?

The plug-in receptacle tester I have is a $20 GB Sure Wire for both standard and GFCI outlets. It is UL Listed #9Z47, as should any electrical equipment you use ... like even the pocket electrical meter I carry around which is also UL Listed #14AK.

apightling wrote:
When you push the button the GFCI will pop . . . will we know why? Maybe we don't care . . .

I think it's important to know. Pushing the button on a plug-in electrical tester completes a circuit between hot and ground with some resistance to create a small current flow (somewhat above the 4mA to 6mA range for a GFCI). However, pushing the built-in test button on a GFCI receptacle actually causes an internal test/trip of the device by creating a small difference in current between the hot and neutral ... which is the real purpose of having a GFCI device.

For anyone interested in the basics related to the operation and testing of GFCI devices, see the following links. Note that the last link to a Mike Holt article has a good explanation of why it's better to check a GFCI receptacle with the built-in test button if possible.

http://ecmweb.com/mag/electric_gfcis_work/index.html
http://ecmweb.com/ar/electric_think_gfci/#top
http://www.mikeholt.com/news/archive/html/master/How_the_Test_Button_Works_on_a_GFCI_Receptacle_01-5-2002.htm

Just my opinion and 2-nickels ... ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif)

--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong
#19

Originally Posted By: apightling
This post was automatically imported from our archived forum.


Thanks Robert. I appreciate your comments. Actually, I think we are agreeing vehumently.


I found GFCI receptacles that would not trip at 4.8mA (that was the reason I selected 25K as the trip resistor value) and some that required 5 times that before they would trip . . . I would call that a situation that requires additional investigation/remediation. However, it’s pretty common.


The Hubbell GFT2G will allow me to determine the trip current of a GFCI from 2-7mA. That’s the one I have ordered. Then when a clients GFCI needs attention I will be able to discuss the parameters and have an accurate means of measuring them.


Meanwhile a few of my home made units that are labeled 4.8mA, 9.6mA, and 24mA with appropriate fault resistors will give me the data I need to accurately assess GFCI outlets. Albiet to a secondary standard until next Monday . . . . . . 'spose I could put a pot in one of them and a digital readout. . . : )



-ap

#20

Originally Posted By: Greg Fretwell
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The question I have would be what tolerance resistors are you using? Did you check them anyway?. The standard resistor is */- 20%