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Confusion about neutral to ground short

• QUESTION: I have a receptacle that has a dedicated 20 amp breaker. Plugging a tester in it, it's telling me I have a neutral to ground short. Although I believe I understand the benefit and necessity to having separate wires for the purpose on appliance safety, particularly ones with metal cases, I've always been confused by these tools ability to test this fault. My confusion is due to the fact that neutral and ground are connected to the same place in the breaker box. So it seems like they will always be shorted. How can the tool possibly indicate that they are not shorted. At my receptacle there doesn't seem to be anything wrong. I suppose there could be a defect in the line itself, but again how would the tester know the difference between a short in the line from the wires being connected at the box. It's a relatively short line to the box. I'm hoping a clear understanding of this concept will help me correct this quite small and simple circuit. Thanks ANSWER: Mick, There is no tester I am aware of that will tell you if the neutral and ground are touching each other at the receptacle when they are already connected together at the main panel. They are basically one and the same except they have different purpose's and separate paths back to the point of union in the panel. Maybe this is being confused with having no ground or having no neutral which the tester will pick up. ---------- FOLLOW-UP ---------- QUESTION: Hm, oh well. By the way, this is what I'm using. http://cgi.ebay.com/Ecos-Accu-Test-II-B7106-Electrical-Test-Kit-Case-NM-/150524497426?pt=BI_Electrical_Equipment_Tools&hash=item230bf58e12 It does an awful lot. But in abbreviation, you plug it in and if just the 1st 2 lights are lit the wiring is correct. Then if you press in the black button and hold the red button the IND light should be off or flashing. If it is on steady the neutral and ground are shorted. I'm thinking it may be just that the line is really short. Probably not more than 10ft, and the tool must use some kind of feedback or resistance to detect it, so it's thinking they're shorted. Because I can't find anything wrong with it. I'll try not to loose sleep about it. It just bugs me that I don't know for sure.

• Answer:

  Mick, Thats an interesting little tester. I'm almost tempted to buy the darn thing. Ok here's how I think it does it. Under normal conditions as we already discussed the neutral (white wire) and the ground (bare or green wire and not connected to each other at the receptacle, only at the main panel so in effect you have a horse shoe loop thats open on one end at the receptacle. So this tester is able to determine if the loop is open or closed. In other words its sending some sort of signal out on those wires and if it takes a short cut right in the box it knows it some how. Exactly how it does it I can't say but its the first tester I've seen that has the ability to do it. Thanks for going to the trouble of sending me the pictures and I may just have to buy that thing !