120V Line Connected to Ground

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fifty60

Senior Member
Location
USA
I have an old house that does not have any grounds ran to the outlets, just line and neutral for 120V. Before turning the breaker on to the outlet I checked for continuity between Line and the metal outlet enclosure and Hot and the metal outlet enclosure. Both checks beeped, so there is continutity between neutral, hot, and the metal outlet enclosure.

I completely removed the outlet from the enclosure and checked continutiy between Hot and the metal enclosure, and I still got a beep. Same thing with Neutral and the metal enclosure....any ideas as to what is going on here?
 

fifty60

Senior Member
Location
USA
I just have a little meterman pocket meter to make the checks. There is a BX connector connected to the enclosure. There is nothing plugged into the outlet though....why would the BX connector cause continuity between the hot and the metal enclosure?
 

JFletcher

Senior Member
Location
Williamsburg, VA
I just have a little meterman pocket meter to make the checks. There is a BX connector connected to the enclosure. There is nothing plugged into the outlet though....why would the BX connector cause continuity between the hot and the metal enclosure?

The BX wouldnt, but any light on on that circuit or anything plugged in elsewhere would cause continuity from hot to neutral, and you have neutral to ground at the panel, and thus hot to neutral/hot to ground where you are doing your check.

I have a GB 'autometer' that would do much the same as your meter. It will beep continuity over any voltage reading.
 

fifty60

Senior Member
Location
USA
I was thinking that, if there is something plugged in it does connect line to hot through the load. So maybe there is something on the same circuit upstream/downstream as this outlet that has something plugged in? So if this is the case, would it be considered normal then to have continuity between hot and the metal outlet enclosure?

This is an ungrounded outlet though...only two prongs...does that change this analysis at all?
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
99% chance you are reading through a load somewhere on that circuit. Unless there is a fault/short somewhere, you shouldn't have any voltage on the metal box or plate.

Take a long extension cord and plug it in to another outlet, take the other end to your "suspect" outlet. With your meter, check from the hot side of the extension cord to the metal on the "suspect" outlet box or plate. If you get 120V then you have a problem or phantom voltage. Any less of a reading is probably phantom voltage.

Even better would be to get a pigtail light socket to use as a test light. Put one side of the pigtail in the hot side of the receptacle and the other end on the metal. If it lights up the test bulb then you've got a problem somewhere on that circuit.
 

fifty60

Senior Member
Location
USA
Is reading through a load on the circuit like this normal? It makes sense....when a load is connected the hot is connected to neutral through a relatively high impedance load...but they are still connected. Since the neutral is bonded to ground, and assuming the metallic enclosure is also grounded (even though there is no ground in the circuit, only two prongs) then I can see how I would have continuity between hot and the outlet enclosure....just very surprised to see that..

my meter is a Meterman PM55 by the way. Fits in the pocket very well, long battery life, but the probes are annoying for transport.
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
And that includes a duplex receptacle with a built-in USB output.
Oooh, new wrinkle I hadn't thought about. Good point.

I also realize now that those cheap little "Night Light" receptacle covers that have clips that connect to the screws and power up some little LEDs will have a little SMPS as well.
 
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