Simple (earth) ground tester

[Marks256]

Does anyone have a usefull SIMPLE circuit for testing earth ground? There are two power receptacles in my room, and i would like to see if they are both grounded... I have two "A" style outlets, as well as a "B" style. I would like to replace the "A" stlye outlet with a "B" style so i can run a few more computers in my room.

The odd reason why i have an "A" and "B" style in my room got me thinking; is the "B" outlet grounded? So, instead of moving furniture around, and popping the breaker to my room to see if there is a ground wire going to it, i want to just do a quick test... That way, i can also test the other outlet when i get it replaced.

sorry if that was confusing...


Here is the "World Electric Power Guide": **broken link removed**

 

[Hero999]

What do you mean by A and B style sockets? Different countries have different types of mains connectors so that makes little sense to me.

The simple way of testing it is to connect a small bulb (a neon will do) from the earth connection to the live wire. You could also measute the resistance between the earth pin and a known good earth connection such as a radiator or water tap.

 

[john1]

Hi Mark,

I have often wondered about this myself.
I would imagine the only way to satisfactorily check the effectiveness of an earth connection would be be to pass a satisfactory current to
earth through it, and see what the resulting voltage drop turns out to
be.

I have often toyed with the idea of making such a piece of kit, but i
have never done so.

In this country there are regulations about the effectiveness of
earthing conductors, and there is test equipment available for testing
them. I have seen people go to great lengths to improve earthing
arrangements on-site in order to meet the requirements for
certification.

Hero, here's a Wiki page showing the various common types.

https://en.wikipedia.org/wiki/Domestic_AC_power_plugs_and_sockets

John

 

[Nigel Goodwin]

Going back years the standard test was a 100W bulb between live and earth, but now earth leakage trips make that useless - it would just blow the trip!. Presumably there are specific tests that electricians know about?, perhaps using a specialised meter?, but it would be country specific.

 

[Bob Scott]

Mark, get yourself one of these:

**broken link removed**

There is a simpler even cheaper model that does not have the GFI test. (Ground Fault Interruptor). They are a handy pocket device for testing AC receptacles for correct wiring anywhere you go in US and Canada.

By the way, The US electrical code says that it is not legal to replace a 2 wire receptacle with a 3 wire grounded receptacle if there is no ground available. In Canada, you can but the code says that you have to label the outlet as non-grounded.

Bob

 

[TheVictim]

An electrostatic potential exists between the Earth and sky. If you have some sort of antenna outside, you should get a tiny spark between it and a true Earth ground. If your antenna is large enough, this potential is enough to run a small electrostatic motor!

 

[Marks256]

By the way, The US electrical code says that it is not legal to replace a 2 wire receptacle with a 3 wire grounded receptacle if there is no ground available. In Canada, you can but the code says that you have to label the outlet as non-grounded.

That is what i want to test for. I want to see if my 3 wire grounded receptacle is REALLY grounded.



Also, aren't the 2 wire receptacles grounded at the frame? I am not sure... i could be wrong... I know nothing about large scale electronics like household electricity, except for how to replace switches... and outlets...

 

[Bob Scott]

Methods #1:
Use a light bulb like Nigel suggested and momentarily connect it between the hot terminal of the receptacle and the retaining screw of the cover plate. If the lamp lights, the box is grounded. If this circuit has a GFCI breaker, the bulb will not light and the GFI breaker will trip, verifying that the box is grounded. If nothing happens go to method 2:

Method 2:
As a safety precaution, you may disable power to this receptacle by switching its breaker off at the main power panel. Remove the cover plate and receptacle. You do not have to disconnect the receptacle. Take a look inside the box. If you see a bare wire screwed to the back of the box, it is a ground wire. If there is no wire screwed to the back of the box, the box ix not grounded.

Older housing including some built just after WW2 used ungrounded 2 wire circuits with no ground wire to the outlets. In this case, you may be tempted to go down to the hardware store and buy one of those little "ground cheater" adapter plugs but your equipment won't be safely grounded unless you connect the equipment ground to a water pipe. Make sure they didn't use plastic pipe.

Bob

There is not "I" in "team" but there is an "I" in "WIN".

 

[TheVictim]

My apartment building recently replaced all the water pipes inside the units with plastic tubing. I do believe the drains are still grounded.

 

[stevez]

I think that Nigel is correct - that there is a standard test fixture and method to actually measure the resistance to ground. You might look in electrician's handbooks. I know I've seen the relatively simple fixtures - just can't recall where.

 

[chemelec]

That is what i want to test for. I want to see if my 3 wire grounded receptacle is REALLY grounded.



Also, aren't the 2 wire receptacles grounded at the frame? I am not sure... i could be wrong... I know nothing about large scale electronics like household electricity, except for how to replace switches... and outlets...

Either BUY or Build a Ground Fault Detectors like as shown in my article.

**broken link removed**

Two wire outlets have No Ground. Just Hot and Neutral.
But Neutral is NOT a Ground.

 

[Marks256]

Two wire outlets have No Ground. Just Hot and Neutral.
But Neutral is NOT a Ground.

I thought the frame that holds the outlets into the wall was supposed to be grounded? I like your circuit, but i don't have any neon bulbs.

 

[chemelec]

I thought the frame that holds the outlets into the wall was supposed to be grounded? I like your circuit, but i don't have any neon bulbs.

Supposed to Be, YES.

Is it Actually, Probably Not.

I have owned a few houses in my life. The one I'm in now Still has some Old Knob and Tube Wiring. REALLY OLD and No Grounds. But at least the outlets are wired correct phase to the wires.

In My Previous house, Someone actually wired up one Outlet with 18/2 Lamp Cord Wire.

You Never Know, Unless you Look or know how to Test it Properly.

NE-2 amps are Cheap. Even Radio Shack might still have some, but they are not cheap.

 

[Marks256]

Well... I got the faceplate off a few minutes ago... I am a bit disgusted...

First, we had to pop the breaker to my room... wow... Who ever labeled the damn breaker box did a horrible job. Nothing was labeled worth a crap, and THERE WERE MISSPELLINGS!!!!!! I thought i spelt stuff wrong! NO! Some moron spelt "light" LITE!!!!!!!

Anyways, we found the breaker that killed the outlet... So as my dad and i got ready to get the flashlight out, i decided to be dumb and try to turn my light on... IT DID TURN ON!! Also, the outlet right next to the one we were trying to replace had power! So, my room is on like two or three different circuits... Idiots...

Well, long story short, the outlet wasn't grounded, so we didn't replace anything. The wire was oldish too... The old mesh coating... I think our house is pushing like 85 years old...



I still want to check and see if my other outlet is grounded... if not I am going to be super pissed...

 

[Nigel Goodwin]

What's 'mesh coating'?.

I still see lead coated wires occasionally - now they are SERIOUSLY dangerous, the two copper wires are covered in flax insulation, with a lead sheathing over all, with the lead used as the earth connection. Other the MANY decades of use the flax has perished away, and if you touch the wire it all crumbles away leaving bare wires!!!!!!!!.

 

[chemelec]

Well... I got the faceplate off a few minutes ago... I am a bit disgusted...

First, we had to pop the breaker to my room... wow... Who ever labeled the damn breaker box did a horrible job. Nothing was labeled worth a crap, and THERE WERE MISSPELLINGS!!!!!! I thought i spelt stuff wrong! NO! Some moron spelt "light" LITE!!!!!!!

Anyways, we found the breaker that killed the outlet... So as my dad and i got ready to get the flashlight out, i decided to be dumb and try to turn my light on... IT DID TURN ON!! Also, the outlet right next to the one we were trying to replace had power! So, my room is on like two or three different circuits... Idiots...

Well, long story short, the outlet wasn't grounded, so we didn't replace anything. The wire was oldish too... The old mesh coating... I think our house is pushing like 85 years old...



I still want to check and see if my other outlet is grounded... if not I am going to be super pissed...

It is REALLY a GOOD IDEA that the room is on 2 Seperate Breakers.

MESH COATING, I suspect you mean a CLOTH Covering.

Sounds like your Old House is "Knob and Tube" Wiring.
No Grounds were used Back Than!
But That is NOT really a Problem, if the Neutral is Correctly wired to the Outlet Socket.

 

[Marks256]

What's 'mesh coating'?.

I still see lead coated wires occasionally - now they are SERIOUSLY dangerous, the two copper wires are covered in flax insulation, with a lead sheathing over all, with the lead used as the earth connection. Other the MANY decades of use the flax has perished away, and if you touch the wire it all crumbles away leaving bare wires!!!!!!!!.

It is REALLY a GOOD IDEA that the room is on 2 Seperate Breakers.

MESH COATING, I suspect you mean a CLOTH Covering.

Sounds like your Old House is "Knob and Tube" Wiring.
No Grounds were used Back Than!
But That is NOT really a Problem, if the Neutral is Correctly wired to the Outlet Socket.

Yeah, "cloth"...

No, it is NOT a good idea to be on two different breakers... I say that because half of my room is shared with two other rooms, and the other half is shared with another couple of rooms!

 

[chemelec]

Yeah, "cloth"...

No, it is NOT a good idea to be on two different breakers... I say that because half of my room is shared with two other rooms, and the other half is shared with another couple of rooms!

Actually it IS.

The Reason for it is Even if a Breaker does go for one of the Outlets in that room, the Other still works.

Actually in Canada, I am Quite sure it is REQUIRED to have more than one circuit and on different breakers in each room.
And Sharing with Other Rooms is Definately OK.
"I Don't know why you think that is a problem"?

Not sure about wiring Codes in the USA, But Probably the same as here.

 

[Marks256]

Well i am no electrician, so, my bad.