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#188658 08/23/09 12:17 AM
Joined: May 2004
Posts: 24
thiggy Offline OP
I have a Snapit three light circuit tester. I was using it to check the recepticals in an old rental house I am preparing for sale. I was checking the outlets, as several have been replaced with three prong grounded types. As I suspected, very few of the recepticals are actually grounded. My question concerns the light combinations that this tester displays. This tester has a chart which shows five problem and one indicator for correctly wired. The combinations of the three lights shown on the chart are as follows: center light on - open ground, right light on - open neutral, no light on - open hot, left and right lights both on - hot/ground reversed, left and center lights on - hot/neutral reversed, center and right lights on - correctly wired. My problem is that on a couple of the outlets all three of the lights were on, and the tester does not list this as a possiblilty. I brought the tester home with my to try it on a couple of known correctly grounded recepticals and it register properly. Does anyone have any idea what may be the cause of all three indicator lights glowing in some instances?

Joined: Dec 2005
Posts: 5
New Member
I found the same thing while troubleshooting some receptacles at my sister's house. A previous electrician had converted a receptacle circuit to 240v to supply power to a window a/c unit. Check your voltage.

Joined: Jan 2005
Posts: 5,370
Likes: 1
Cat Servant
Those testers are but aids - and no substitute for either training, or a real meter.

A number of things will lead to confusing readings; among them are multiple faults and broken receptacles.

What you should do when you get multiple readings, or nonsense results, is to kill the power and remove the receptacle from its' box. Then you can start checking things.

Often these problems can be traced to one spot. I find it easier to locate the problem by first checking ALL 4receptacles. Ones that indicate problems get a piece of red tape on the faceplate; when I'm done, it's often possible to see a pattern. For example, they may all be on the same circuit.

Joined: Nov 2005
Posts: 827
Those indicators are just the three combinations. H-N and H-G should be on, G-N should be off. If those indicators are neon, which takes around 60 Volts to ionize, you've got a big problem! I never use those things because the DMM is going to provide the info I need. Why not use the meter first?

Joined: Nov 2007
Posts: 763
I use a 3-light receptacle tester all the time as part of the final room by room receptacle check out on new finish wiring. They make it a lot faster and easier to check the TR receptacles required for new and remodel work.
Granted they are not a comprehensive tester, but because they are so handy, that I often find myself using them for initial troubleshooting on a service call before getting out my meter and removing a receptacle and then also again to verify my work after replacing a receptacle.

KJay #188825 09/05/09 12:48 PM
Joined: Jul 2004
Posts: 9,791
Likes: 14
These testers can light all 3 lights (two dimly) if a bad connection exists on the ground or neutral side. Usually that is just a worn receptacle. You end up with 2 lights in series with the hot and one grounded conductor.

Greg Fretwell
Joined: Jan 2004
Posts: 28
I don't post much here but I have to say I recently bought an Ideal 61-165 and I like it big time. I now go through all the tests on almost every outlet I deal with just because I can.

Joined: Jul 2002
Posts: 8,432
Likes: 3
Welcome back there Matt,
Personally, I'd never use one of them plug-in testers.
If they were as good as they said they were, everyone would be using them and we wouldn't need test equipment like meters and the like.

I've had a pair of these for the last 20 years, pretty much you can test anything AC or DC from 120V up to 750V safely.

[Linked Image from]

{Sorry that is a shocker of a pic}

It has an internal solenoid (by pressing the black button)and will draw about 240mA, so there is no getting any "ghost voltages" mucking up your readings.

One other thing about them is, they are made to last, they are sealed against moisture and when the cord between the probes are un-wound, they can be draped over your shoulders (around your neck), so you know where they are.
In umm, hindsight, it does not pay to sit on one of these testers, them probes are very sharp, as I learned once. mad grin

Joined: Mar 2008
Posts: 47
sbi Offline
always use a meter or a "wiggy". When you are doing electrical work your meter should always be handy

when in doubt jump it out
I happily work for slumlords
sbi #188908 09/09/09 05:16 PM
Joined: Jul 2004
Posts: 9,791
Likes: 14
Three light receptacle testers are handy because you can always have one in your pocket but they don't tell you much more than you can figure out with a night light and they can simply lie to you.

Greg Fretwell
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