window frame zapping

Hi all, I got a small shock (electrical and the other) while leaning against a steel window frame while handling speaker wires in a house today.
The home is built with concrete walls and all windows are steel. I measured around 100 VAC between either speaker wire wrt the window frame with the amp on or off. I was able to light up an LED too, though the current couldnt have been much as I didnt use a limiting resistor and the LED didnt burn out.
What the hell is going on??
Hoping for some advice as to what to check.
Thanks, Mark
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| I got a small shock (electrical and the other) while leaning against a steel | window frame while handling speaker wires in a house today. | The home is built with concrete walls and all windows are steel. | I measured around 100 VAC between either speaker wire wrt the window frame | with the amp on or off.
You seem to be posting from Australia, so I will assume your have 240 volts line-to-neutral/ground power system.
Does the power plug on the amplifier have 2 prongs (ungrounded) or 3 prongs (grounded)? You can't reverse an AU plug, so check to see if the outlet or power cord into the amplifier is miswired.
| I was able to light up an LED too, though the current couldnt have been much | as I didnt use a limiting resistor and the LED didnt burn out. | | What the hell is going on??
If a 3 prong (grounded) plug is involved, and the ground wire is attached to the amplifier frame, as it should be, it may be the case that the ground wire in the outlet or branch circuit is NOT CONNECTED to the real ground. It would them be capacitively coupled to both the hot (240V) and neutral wires, giving you something about half way in between with very little current available.
| Hoping for some advice as to what to check.
Check to see what voltage you get between the GROUND slot of the outlet and the window frame. If nothing there, check the frame of the amplifier when it is plugged in, and also when it is unplugged. There is also the chance of another device in the A/V system causing this if more than one is present and they are interconnected. Pull all connections and test each one by one if that is the case.
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| ***I did some checking, and pulling out the turntable (the only three | pronged device) finally shut the LED down. | I then measured between 'house earth' and the window. | The same 100 volts was there and lit the LED as before. | I'm guessing your theory involving Capacitance is having a role to play | here. | Is this due to to bad earthing? and am I likely to be paying for energy i'm | not getting? | What would be the best way to fix the problem?
Yes, the earthing is likely to be faulty. There exists a remote possibility the window frame is energized some other way and the "house earth" is just the return for that energy in the window frame.
It is not likely you are paying for energy you are not getting/using, since the current is so small. But that does not rule out some other fault.
If the problem is what I believe to be most likely (a broken ground/earth wire somewhere between the outlet and the panel where the ground/earth is connected to the system neutral and the earth electrode(s)), it will not cause loss of energy unless something else is at fault. Such faults that could result in high leakage current or, worse, electrocution hazard to people, should result in the circuit breaker tripping off because of high current to the ground wire. With the broken ground/earth connection, that won't happen and if such a risk exists, it will persist.
If the ground/earth wire were connected to neutral and ground correctly, any energy it is charged with through capacitive coupling would be drained fully to neutral and earth. It apparently is only "draining" through the capacitive coupling (and so it is about half way in voltage).
To fix this, hire an electrician who has the appropriate license/permits in your location. It MAY be as simple as a loose connection in the outlet. It is more likely to be a loose connection in the electrical panel. Unless you are an electrician, you don't want to be messing around in there.
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| Just a quick question while i'm here. | Is it true that both the Active and Neutral wires come in off the street?
Yes.
| If thats the case, does that neutral simply terminate to ground at a sub | station way before the power station or does it go all | the way?
It could be isolated at a transformer by being grounded/earthed on the secondary side, and not connected across to the primary. However, at least in the USA, it is typically connected between primary and secondary. So the answer is, it very well could go all the way to the power station. There would be many points along the way where it would be earthed.
| On the other hand, does only an active come into the house and returns to | ground at the house only.
The power return is through the neutral, not earth. The neutral is earthed for various reasons/benefits. But it is usually earthed at only one point near where it enters the building. Duplicate earthing can cause problems such as return current flowing through the earthing electrodes, corroding them.
Some very high voltage transmission power lines are designed to use earth itself as a return path. But this is rare.
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Generally in Australia the system distribution, both the very hi voltage grid and the local street high voltage is 3 phase DELTA and hence no neutral. There is then a large 40kva or more transformer in the street, sometimes on a pole (outside my house) and sometimes in a box on a pad or hidden in buildings. These each serve more houses than the typical US pole pig. The neutral originates in the 3 phase WYE secondary output and is grounded there. The neutral is again connected to the ground at the building entry box and hopefully nowhere else. There are some hi voltage Single Wire Earth Return (SWER) systems in the bush and of course to work they have the neutral and the ground connected on both sides of the transformer at the consumer.
Gloat (- for USA home workshop people, 3 phase 230/400 volt power is available anywhere (except at SWER instalations) just for the cost of installation or sometimes for free. Most ducted Air cons are 3 phase so lots of houses already have it installed.
John G.
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| Generally in Australia the system distribution, both the very hi voltage | grid and the local street high voltage is 3 phase DELTA and hence no | neutral.
So the single phase pole pigs would have two insulation bushings for the primary connections?
| There is then a large 40kva or more transformer in the street, sometimes on | a pole (outside my house) and sometimes in a box on a pad or hidden in | buildings. These each serve more houses than the typical US pole pig.
How many houses can be served by one 40 kVA transformer down under?
| Gloat (- for USA home workshop people, 3 phase 230/400 volt power is | available anywhere (except at SWER instalations) just for the cost of | installation or sometimes for free. Most ducted Air cons are 3 phase so lots | of houses already have it installed.
Three phase is fine to have around if you don't have the penalty of having and odd voltage. I'm sure nothing for consumers is made designed to be run from 460 volts, so no one would have a reason to get 230/460 volt split phase power. The voltages would strictly be 230 and 400 (240 and 415 in legacy installations). In the USA and Canada, many consumer appliances use 240 volts single phase. But you don't get that 240 volts where three phase power is provided in the form of the 120/208 volt system.
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wrote:

There are NO single phase pole pigs except the remote SWER installations. All street transformers are 3phase 3 wire in 4 wire out. and as far as I can find out higher voltage distribution transformers are alwys 3 wire in and 3 wire out with only relatively light lightining protection wires at the top of some tower runs.

It is hard to tell because the 4 wire 230/400 wireing is often looped with more than one transformer connected to a bigger group with hand operated disonnects for fault isolation.

I think I undestand the various voltage problems with three phase and split 120/240/208/ Anything you are likely to buy here is either 1 phase 230v or 3 phase 230/400. There are some legacy kitchen ovens that were 2 phase. Of course it is only a short while since we started to move to 230 from 240 and some years ago Western Australia was 250.
My comments about how easy it is to get 3phase were aimed, in jest, at home machinists in the US who buy commercial equipment then have to resort to some odd convertors to get them to run.
John G.
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| wrote: |> |> | Generally in Australia the system distribution, both the very hi voltage |> | grid and the local street high voltage is 3 phase DELTA and hence no |> | neutral. |> |> So the single phase pole pigs would have two insulation bushings for the |> primary connections? | | There are NO single phase pole pigs except the remote SWER installations. | All street transformers are 3phase 3 wire in 4 wire out. and as far as I can | find out higher voltage distribution transformers are alwys 3 wire in and 3 | wire out with only relatively light lightining protection wires at the top | of some tower runs.
Well, that certainly makes it much easier to get three phase service, even if most homes are only getting one or two phases from that transformer.
But if there was a single phase one, it would have to be the two bushing type. Suppose you have a neighborhood area, but off to one side of it at some distance (say 1km) not suitable to run 230 volts directly, is a home isolated from the others. The closest place to feed it is from the same distribution going around these neighborhood streets, because that is also the way the road goes to that house. That distribution is delta, so there is no neutral handy. So you'd have to run at least two of the distribution wires out that 1 km road, and put a transformer out there. Would the do this with three wires and put a three phase transformer, anyway?
|> | There is then a large 40kva or more transformer in the street, sometimes |> on |> | a pole (outside my house) and sometimes in a box on a pad or hidden in |> | buildings. These each serve more houses than the typical US pole pig. |> | |> How many houses can be served by one 40 kVA transformer down under? | | It is hard to tell because the 4 wire 230/400 wireing is often looped with | more than one transformer connected to a bigger group with hand operated | disonnects for fault isolation.
So it forms a "networked service".
|> | Gloat (- for USA home workshop people, 3 phase 230/400 volt power is |> | available anywhere (except at SWER instalations) just for the cost of |> | installation or sometimes for free. Most ducted Air cons are 3 phase so |> lots |> | of houses already have it installed. |> |> Three phase is fine to have around if you don't have the penalty of having |> and odd voltage. I'm sure nothing for consumers is made designed to be |> run from 460 volts, so no one would have a reason to get 230/460 volt |> split |> phase power. The voltages would strictly be 230 and 400 (240 and 415 in |> legacy installations). In the USA and Canada, many consumer appliances |> use |> 240 volts single phase. But you don't get that 240 volts where three |> phase |> power is provided in the form of the 120/208 volt system. |> | I think I undestand the various voltage problems with three phase and split | 120/240/208/ | Anything you are likely to buy here is either 1 phase 230v or 3 phase | 230/400.
What if you have a very high power device that can only be run single phase? Would that not be wired for 400 volts?
| There are some legacy kitchen ovens that were 2 phase. | Of course it is only a short while since we started to move to 230 from 240 | and some years ago Western Australia was 250. | | My comments about how easy it is to get 3phase were aimed, in jest, at home | machinists in the US who buy commercial equipment then have to resort to | some odd convertors to get them to run.
And that is a well aimed jest. It is in fact a real issue. My grandfather did get 3 phase power for his wood shop, which was in a detached building on the side of the house distant from where the power came in. This was done in 1961. My guess is he had assumed the three phase power would be in the form of "center tapped delta" without him necessarily understanding the details (he was not an engineer, he was a school teacher of subjects wood shop and business math). But instead of getting center tapped delta he apparently got "208Y/120" and wired 3 phases underground to the shop and just 2 phases into the house. They had the "slow heating" problems with that lower line-to-line voltage on everything, and it was most problematic for my grandmother who was always doing cooking for many things. The house was one of those early "all electric" houses which had no gas service at all. My grandfather was trying to get the electric issues corrected for the next 11 years until he passed away. Perhaps the new owners afterwards would have not needed three phase and single asked for the service to be reverted to single phase.
I posted a while back a description of the kind of electrical system I would have used if I could, back in time, have determined what it would be before all the economics locked us into what we have now. It would have been a system somewhere beteween what .US and .AU have now. But I would have also avoided using directly connected line-to-neutral light bulb connections. The service would have been either 144/288 or 288Y/166 with all utilization wired line to line. Incandescent lights would have been wired through a step down transformer to operate at 24 or 12 volts.
OTOH, if the whole world had simply done 400Y/230, fewer issues would exist today. An electric stove could be wired to 230 volts at just 40 to 60 amps while if only single ended 120 volts were all that people got in .US then it would have needed 80 to 120 amps. So we needed that extra split phase to handle the extra voltage for a few big appliances. The problem comes from the need to have TWO single phase voltages, which cannot be reproduced using simple three phase wye/star systems. Eliminating that need solves it.
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wrote:

Pity you did not ask this question 2 weeks ago. I have just come back from a 4000 km drive to Adelaide and could have taken more notice of installations closer to towns than those with SWER. I think some small phase to phase transformers may be used as you suggest.

I dont know of any but I guess it is posible, like as I said some old kitchen ovens, and I do not know if you ever had them but houses had fire, gas or electric heated boilers for washing clothes before washing machines and I think some of them were also 2 phase.

john g.
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Don Kelly snipped-for-privacy@shawcross.ca
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snipped-for-privacy@ipal.net writes:

Vancouver Island is fed power from the main BC grid via a HVDC submarine cable. I think the voltage is around +- 200 kV. The rectifier station is a few miles from the coastline, and the HVDC is carried on towers to the point where the submarine cable comes ashore. This point is right next to the road access to the main ferry terminal, so it's quite visible. The overhead lines look a lot like standard HVAC, but there are only two conductors, not three.
In addition, there's another single conductor that goes from the rectifier station to the shoreline of a nearby bay, where it connects to an array of ground rods. There's a fence around the ground rod array with warnings about dangerous voltages - not what you'd expect from obviously "grounded" electrodes.
From various stuff I've read, I think this is what's going on: Normally, all the current is carried by the submarine cable conductors, and the ground rods do nothing. But if one of the conductors ever becomes open, the ground rods at this end (along with another array somewhere on Vancouver Island) provide a return path via sea water that would allow the remaining good conductor to deliver half the normal power. This much DC current would likely corrode the ground rods pretty fast, but is better than losing the entire cable capacity.
These features can be seen (somewhat fuzzily) in Google Earth. The rectifier building is part of the substation at (49.090456 -123.041981). (This is latitude/longitude in degrees) The terminal where the HVDC lines connect to the submarine cable is at (49.028194 -123.100258). And I believe the ground array is what you see at (49.057122 -123.029581).
(It's actually a bit more complicated than I described, because there are multiple submarine cables. There are older cables, lower in capacity, fed from a building in Tsawwassen, between 4 Ave and 5 Ave. The installations described above are for a more recent higher-capacity cable. And BC Hydro is in the process of adding yet another cable, but it's reusing the old Tsawwassen connection route).
    Dave
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| From various stuff I've read, I think this is what's going on: | Normally, all the current is carried by the submarine cable conductors, | and the ground rods do nothing. But if one of the conductors ever | becomes open, the ground rods at this end (along with another array | somewhere on Vancouver Island) provide a return path via sea water that | would allow the remaining good conductor to deliver half the normal | power. This much DC current would likely corrode the ground rods pretty | fast, but is better than losing the entire cable capacity.
And sound a bunch of alarms, too :-)
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On 16 Mar 2008 17:18:58 GMT, snipped-for-privacy@ipal.net wrote:

DC links typically get converted back to AC for the distribution segments.
So the converter station and the source make for only ONE path for the link.
No "ground rods" are used for such huge power passes. It is a far different system.
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On Mon, 17 Mar 2008 09:57:23 -0700 StickThatInYourPipeAndSmokeIt
| On 16 Mar 2008 17:18:58 GMT, snipped-for-privacy@ipal.net wrote: |
wrote: |> |>| From various stuff I've read, I think this is what's going on: |>| Normally, all the current is carried by the submarine cable conductors, |>| and the ground rods do nothing. But if one of the conductors ever |>| becomes open, the ground rods at this end (along with another array |>| somewhere on Vancouver Island) provide a return path via sea water that |>| would allow the remaining good conductor to deliver half the normal |>| power. This much DC current would likely corrode the ground rods pretty |>| fast, but is better than losing the entire cable capacity. |> |>And sound a bunch of alarms, too :-) | | | DC links typically get converted back to AC for the distribution | segments. | | So the converter station and the source make for only ONE path | for the link. | | No "ground rods" are used for such huge power passes. It is a far | different system.
Something has to be there in the ground. What do YOU think it is? Some metal that cannot be corroded? Some conductive ceramic?
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On 17 Mar 2008 18:09:16 GMT, snipped-for-privacy@ipal.net wrote:

For Megawatts? It ain't ground rods.
It is likely a huge slab at each end that is some power station enhanced version of an ufer system sitting on a wet link to bedrock.
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On Mon, 17 Mar 2008 12:55:48 -0700 StickThatInYourPipeAndSmokeIt
| On 17 Mar 2008 18:09:16 GMT, snipped-for-privacy@ipal.net wrote: | |>On Mon, 17 Mar 2008 09:57:23 -0700 StickThatInYourPipeAndSmokeIt
|>|
wrote: |>|> |>|>| From various stuff I've read, I think this is what's going on: |>|>| Normally, all the current is carried by the submarine cable conductors, |>|>| and the ground rods do nothing. But if one of the conductors ever |>|>| becomes open, the ground rods at this end (along with another array |>|>| somewhere on Vancouver Island) provide a return path via sea water that |>|>| would allow the remaining good conductor to deliver half the normal |>|>| power. This much DC current would likely corrode the ground rods pretty |>|>| fast, but is better than losing the entire cable capacity. |>|> |>|>And sound a bunch of alarms, too :-) |>| |>| |>| DC links typically get converted back to AC for the distribution |>| segments. |>| |>| So the converter station and the source make for only ONE path |>| for the link. |>| |>| No "ground rods" are used for such huge power passes. It is a far |>| different system. |> |>Something has to be there in the ground. What do YOU think it is? Some |>metal that cannot be corroded? Some conductive ceramic? | | | For Megawatts? It ain't ground rods.
For megawatts it isn't SMALL ... but it has to be SOMETHING stuck into the ground. Are you saying "ain't ground rods" because the SHAPE doesn't look like a rod (or a huge array of big ones)?
| It is likely a huge slab at each end that is some power station | enhanced version of an ufer system sitting on a wet link to bedrock.
OK, I'll call it an "earthing electrode". There, it isn't a "rod".
Now back to the original question ... will it corrode?
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On Sun, 16 Mar 2008 07:00:04 +0000 (UTC), snipped-for-privacy@cs.ubc.ca (Dave Martindale) wrote:

I think the Bonneville to LA DC intertie ("Celilo link") is Earth return.
http://en.wikipedia.org/wiki/Pacific_DC_Intertie
I am not sure but The return on DC links is Earth in most cases I have seen.
It makes sense. Cost and operation wise.
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