Weird electrical problem!!

[Ovi]

Hi everyone!
I’ve got a really strange problem this time! Today I was checking the earthing of the plug point to which my computer is connected, using an analog multimeter. The computer is connected, along with the monitor and other things, to a multi-point extension cord, which in turn is connected to the wall socket. First I checked the wall socket (after unplugging the extension cord from it), and as expected, the multimeter showed current b/w the earth and the live point, indicating that the earthing was proper. Also as expected, there was no current b/w the neutral and the earth line. But when I checked the same in the extension cord, after plugging it into the wall socket, apart from showing current b/w the earth and the live point, it also showed a very small current b/w the neutral and the earth point!!!! This was when nothing was plugged into the multi-point extension cord!! Now how can that be possible? Is it due to some induced current or something? The extension is only 2 meters long. Any suggestions would be appreciated.
Cheers
Ovi

[Greebe]

How much current are you talking about?

[Ovi]

Hi Greebe
The voltage b/w the neutral and the earth was of the order of around 10 volts, the operating voltage here being 220v

[Greebe]

Surge supressor type outlet strips have at least one MOV (Metal Oxide Varistor) in them... the better ones have three... one between Hot and Ground is the common setup, but the better ones may also have one between Neutral & Hot and between Neutral & Ground. If one is leaking due mostly to a previous surge then it would induce a voltage drop which could be what you are seeing. Another possibility could be that one of the plugs fingers are not making good contact thus inducing restistance giving you the same indication.

[Ovi]

Hi Greebe!
Thanks for the ultra quick reply!
My extension strip is not a surge suppressor! Its a plain jane multi-socket extension. I opened it up to check, and as expected, it just has the sockets directly connected to the cord, no other components! I'm sorry I forgot to mention this!
Also, the voltage b/w ground and live is normal 220v, what is abnormal is the ~10v b/w ground and neutral, when it should be zero!
Cheers
Ovi

[Greebe]

Well even with out MOV's in it a poor connection through the plug fingers could also cause this regardless of the operating voltage which also would include any metal to metal junction connecting power. Are you sure that it's truely ZERO from neutral to hot in the electrical outlet?

[Ovi]

It is truly zero b/w earth and neutral in the wall outlet! I'll try using another extension, and will report back tomorrow.
Cheers
Ovi

[rylan]

What you have to remember is that the Neutral line is just that.. neutral. It is -not- a ground. The neutral line acts as a return current path for the hot.. so the neutral line can have quite a bit of current traveling through it. And since copper has some resistance, that current induces a low voltage (which you saw, with the neutral hanging around 10V or so). Remember good old Ohm's Law.. V=IR.. you've got resistance and some current, so you're gonna have some local voltage on neutral
Incidently, that also causes the current you saw between neutral and ground, since neutral is at a higher potential than ground, so current is going to flow.

Also, you may get some induced voltage in the neutral due to the wiring in the power strip.. if it is a cheap one, they probably used crappy insulators.

[Greebe]

Pardon me rylan but you are incorrect, neutral & ground are tied to the same point within the main electrical service box. From there it should be earth grounded.

Insulators should not induce that kind of voltage reading. Even if crap I'd be extremely hard pressed to believe it.

Regardless, my summation of the problem is correct... there is either a poor connection at the plug or the bus within the outlet strip causing this problem.

Ovi, in your original post you mentioned current... this is different than voltage. Which was my original question to you... what is the current (not voltage) potential?

[The PIT]

Don't know about America but I'm pretty sure in the UK the netrual is ground at the sub station and the earth at the house itself.

[Sasq]

Australia is the same, and I think here is too

Dan

[Greebe]

it's a universally standard safety practice

[Dr Mordrid]

Yuppers. Electrons behave the same in the US, UK, Europe, Japan and OZ

Dr. Mordrid

[rylan]

Hmm.. odd.. cuz the wiring at work we had problems with the neutral not being properly shielded, and the electrician said that the neutral isn't grouned in the building, but returns to the service station outside.

[spoogenet]

Ovi,

When you first posted, did you mean to say there was current or that there was a voltage difference?

b