Strings Shocking Me

[Maiden69]

I know were I though that it was wrong, I thought that by saying poly phase you meant 2 phases completing the 120. Not that the voltage was bleeding into some other "ground" (or load) and not making it to the neutral loop.

[thedoctor]

Uhmm, say again? I almost know what you were saying but something got in the way.

[Kyle Cavanaugh]

Slap me if I'm wrong here, but isn't the common (-) supposed to be connected to the ground? That would mean that ifyou measured across the common and ground, you should get 0 volts as it's shorted out. If you get a voltage then obviously it's not right. There could just not be a ground wire attached, as well/ The last owners of our house upgraded from 2 prong to 3 prong and never changed the original wiring itself.

ONE THING'S FOR SURE, ALWAYS WEAR RUBBER SOLED SHOES OR YOU ARE AT MUCH GREATER RISK FOR BEING THE SHORTEST PATH TO GROUND! Obviously, you were. Considering the amp is probably isolated from ground by the transformer (s), your problem may lie in that.

[thedoctor]

Maiden, I got your jest and you be right. When the current don't make it through the CORRECT path which would be de neutral, it go astray and makes for some (insert your own term here) voltage readings. Understand that these voltage readings mean nothing except that current is not flowing through the correct path and is making for wierd readings anywhere else people are using power. Just get in your mind that every watt of power the AVERAGE user of elec. is 120vac single-phase. Ain't no TWO hot wires involved. One hot, one NEUTRAL!! When neutral goes to hell, so does your handbasket. No two hots are involved in 120 volt wall-outlet power. One hot, one neutral.

[Maiden69]

Ain't no TWO hot wires involved. One hot, one NEUTRAL!! When neutral goes to hell, so does your handbasket. No two hots are involved in 120 volt wall-outlet power. One hot, one neutral.

Yeap, I was always aware of this! Like I say I got confused when you posted

that is not correct in a polyphase circuit

I thought at that moment that you were talking about 2 60's instead of the 120. Like I said above I got were the confusion started!

You got to understand that all my schooling has been in spanish, so the terms and everything else I know is not in english, so that may be why the reason for you to kinda not understand what I was posting.

[Paul Marossy]

In a modern house, two "hot" lines and a neutral come in from the transformer on the pole or slab outside the house.

This line is where I got the impression that there were two hot lines. One hot, neutral and ground is more familiar to me. Anyhow, now I get the idea of what the neutral's function is. I always wondered about that, but I never was that determined to find out the answer.

[thedoctor]

I don't know why I didn't think of this sooner. In CODE wiring, ie: wiring that is installed according to the NEC or National Electric Code, the wires going to a 120 volt AC wall outlet has three colored wires. Black is the "hot", white is the neutral and green or bare copper is the ground. That is for single-phase 120VAC. When a polyphase unit is wired, such as a dryer or range, there SHOULD be 4 wires! 2 hots, a neutral and a ground. 2 blacks, a white and a green/bare. In the case of, say, a water heater, where no single-phase is needed to run digital displays, fan motors, etc. 2 hots and a ground are all that is required. 2 blacks and a green/bare. Try to explain this to an 80-year-old women that bought a new range and wants to know why her kitchen needs to be rewired!! And don't get me started on heatpumps! The installer always says the electrician is an idiot!

[Paul Marossy]

Now we're talking. Black is hot, white is neutral and green or bare copper is ground. That seems to be pretty standard. The two hot thing threw me off, but it makes perfect sense now. Thanks for taking the time to explain this!

[ToneMonkey]

Is your dorm individually metered or is the whole block group metered. How I'd imagine that the electrical layout in the block goes like this (this is for UK, but I should think that barring a few values, it'd be done the same way over there).

Connect onto 11,000 Volt HV cables.

Run HV cables through a Ring Main Unit and into a Transformer (Tx) that will step down the voltage from 11,000V to 400V.

LV cables run from the LV distribution pillar attached to the substation, to cutouts at the entry to the building

LV cables exit cutouts and rise up building on steel tray

LV cables attach to cutouts at the bottom of a Multi Service Distribution Board (MSDB)

The MSDB has for example 24 ways comming off it it (8 No. ways per phase)

1 way for each room supply

Ground path is connected between various MSDB's so that there is always a return path should it be disrupted.

I would say that from the quick reading of the thread that I just had, that the problem will be somewhere between the MSDB and the outlet. Get the hybrid cable checked (as someone said, someone has probably put a nail through it). You haven't put any pictures up directly above the plug socket have you?

[thedoctor]

Nope, Italy, Spain and the UK have not developed a standard code. A lot of Spanish wiring is 200 vac without a neutral and almost ALL of Italy is without neutral. Japan has a 200 volt with neutral system and I believe the UK runs both neutralled and not. Hence the required isolation xfmr for US stuff if is grounded. Hotels in the UK are very accomodating about this. Not so much in Italy.