Whenever im touching the strings on my guitar, and im touching the ground bare foot, i feel a small zap. I only feel it if i slightly touch the strings, bridge, or any part thats connected to ground. When i grab the neck and strings with me whole hand i dont realy feel it. I know the problem is the adapter, I have another adapter that works correctly but it is extremely noisy and unusable. Also, the current faulty adapter makes a lot of noise if im not touching the strings (or any ground point, like the pedal enclosure), and it goes away when im touching them and my feet are on the ground. I've already orderen another power supply but it is going to take a while to ship, i was wondering if there is anything i can do to fix my current adapter? I've already gone through 3 batteries and its not convenient like this. Thanks!
You're describing a minor amount of AC line leakage. A major amount of AC line leakage would kill you when you do that.
Whether you can fix it or not depends on the nature of the supply and your technical skills. If it's a glued-together plastic box and has only two prongs on the case for plugging into the wall socket, chances are very dim. Even if you do crack it open to work on it, and even if you can dope out what to change to eliminate the AC leakage, chances are poor for gluing it back together. If it's a power supply you made out of bits and pieces, you have a better chance of fixing it, and we'll start asking questions about the internal schematic and packaging.
There is one relatively sure cure: an isolation transformer. You're getting the leakage because one side of the AC line is "neutral" and connected to earth ground at your breaker box and out on the service pole. The "line" or "hot" wire then swings +/-176V peak, 120Vrms around the neutral. Any leakage from the line to the rest of the circuit is what you're feeling, because you're the human conductor between the "hot" wire and real, no-fooling planet earth ground. An isolation transformer breaks the connection of the neutral to planet earth, so the AC line to the adapter no longer has a path to the planet with you in it. Of course, you could just wear shoes and be careful about it until the right/good/safe adapter comes.
In any case don't go fooling around in there unless you have more knowledge of AC power lines, leakage, etc. We really would rather that you stay alive and/or don't burn down your house.
I was just about to say that i measured 9.6v DC on my multimeter, but when i switched to AC it also measured 19 on the same spot. I'm guessing you are right about the ac leakage, Is it possible that this would have done any damage to the pedals?
Yes, it's possible that a pedal got damaged...I think you'd know by ear if that happened though. You will have to go thru them with your batteries installed and see if they perform OK.
Don't bother to try to 'fix' the faulty adapter...you are more likely to make things worse, and perhaps shock yourself dangerously (fatally?). We'd rather you wait until your new adapter arrives!! Use batteries until then :)
You can get some protection at the guitar itself by breaking the direct connection from the strings and bridge to ground and insert a resistor of about 220K in parallel with a capacitor (rated for line voltage divided by a derating factor). This provides DC isolation and some AC impedance to ensure the bridge and strings stay close to AC ground.
This does not solve the power supply problem and the noise generation when you are not touching anything; only the new supply can do that.
QuoteI know the problem is the adapter
If there is a fault in the device I wouldn't use it. It can actually be dangerous.
How many mains plug pins does the adaptor have?
The other side of the coin is the adaptor isn't fault, it's just like that. That means you need to buy
a different adaptor.
If you want to continue with the device ...
The best interim solution is to connect the ground on the amp or effects to a mains ground point.
It will divert the leakage away. Sometimes this can be done using an alligator clip from a 6.5mm jack to the metal case of a device that has a three pin plug.
What about adding a filter to the noisy adaptor you have instead?
If it's a two pin mains plug: You could build the little circuit in section 6.4 and test according to section 6.6:
http://www.ebme.co.uk/articles/electrical-safety/335-electrical-safety-tests
Please wear shoes!!
Working with electrics on concrete or dirt is extra dangerous. Concrete and dirt are not great conductors but conduct a lot better than your skin. YOU get most of the voltage leakage.
Your *amplifier* should be GROUNDED. It should have a 3-pin wall-plug into a properly wired 3-pin outlet. If you have this, and get signal through, then the guitar cord ground will divert leakage from un-grounded pedal power packs to ground rather than through you to concrete/dirt. Amplifier makers have really cleaned-up their act in recent decades: they hate shocked customers (and survivors' lawsuits). The amp should solidly ground your whole guitar chain. But can't, if you have busted-off the ground pin, used a 3/2 adaptor, or if the house wiring is incorrect.
The adapter has 2 pins like most 230v adapters; i live in EU. I dont have an actual high voltage amplifier; i use a small lm386 Ruby variation. I have tried filtering the other noisy adapter with that Beavis Audio circuit but it doesnt do anything. I went to the local market today and i thought i scored this 9.6V used adapter for 2 bucks, then i came home, tested it and it measures 14v!
During the time i had the failty adapter i have built two pedals which i have only used with the failty one, so i cant tell if they are damaged because i dont know exactly how they are supposed to sound like. My basic understandin is that all passive components like resistors, caps, diodes and such should be ok. The only thing that could be damaged are transistors and op amps?
you can get decent effects power supplies for around 20 quid which will
come with 6-10 way chain leads...
i use mine for testing, playing, breadboarding, never had a problem.
worth it for the peace of mind, and above all safety.
http://www.effectspedalpowersupplies.co.uk
no affiliation, other than being a customer...
you can get power supplies with 9v and 18v options too for around the same price on ebay etc...
be safe. 8)
=================================
Electric shock from power supply (and how to fix it?)
=================================
That would be a nice title to a AC/DC tribute band's mixtape!
> ...i cant tell if they are damaged
Never mind the pedals. It is YOU we are worried about.
Powered by what?? Another 2-pin supply?
You NEED a 3-pin somewhere. Your gear (and exposed metal on it) MUST return to wall-outlet Ground.
I worry especially about $2 thrift-shop warts, which may have way-excessive leakage due to age or abuse.
There should be a data label on the power supply.
For 2pin, you should have the "double insulated" square-within-a-square symbol. Double Insulated reduces the chance of the output getting into contact with the AC supply due to an internal fault. Generally, this is very safe, but if the psu has been involved in a serious voltage surge (lightning strike in your area?), the insulation can still be "punched through" and then you can have leakage from the AC input to the output.
If it does not say "regulated" it isn't. Pedals really want regulated. Amplifiers can usually get by with just the #2 type in the following list.
DC supplies can be either...
#1: Transformer + rectifier & nothing else.
#2: As 1 but with a smoothing capacitor on the output.
#3: Linear regulated. The ideal type.
#4: Switchmode (SMPS) regulated. Lightweight. May say "only for office/IT use" in which case it is too noisy/spiky for audio.
For #1, it is possible to measure both AC and DC. The AC is the ripple voltage.
For #2 it should measure very little AC off-load, but will show some as load increases as the smoothing capacitor can't fully charge up.
For both #1 and #2, voltage off-load can measure higher than the rated voltage. Rated will only be true at the rated current load. Plus or minus the variation in AC supply voltage.
To check for stray voltage on exposed metalwork, you need...
A known AC supply earth point. The metal of something with a 3pin AC plug plugged into an outlet (doesn't have to be switched on) can serve. Continuity test that it is connected to the earth prong of its AC plug to prove this earth point is true.
Connect a 100k to 150k as a "shunt" resistor across the voltage test terminals of your multimeter. If you don't add a shunt resistance, the high sensitivity of the meter input will pick up harmless stray voltage that will only confuse things.
With one meter probe on your earth point, test for AC & DC voltages with the other probe on the metalwork of your gear.
Handling potentially dangerous things just to find out if they are dangerous, can earn you a Darwin Award! So take precautions - insulated footwear, insulated tools, don't touch directly etc...
Ok guys, the other psu arrived and its basically doing the same thing. It maybe the problem of the power outlet, i will test this in another house. Or maybe this adapter is also faulty, it's not a Boss original. It's a Soundstation psu10, it is actually "designed" for pedals (Soundstation is a guitar and amps company)
Update: tried it at my neighbour's house, same thing
There are many things that could be contributing to this.
First, there could be similar problems with your house and your friend's house if they were constructed before the ... um... mid 1960s. That was when conversion to three-wire was under way, and the retrofits were not always of good quality, or even done. There is at least some possibility that both houses have a similar problem. Maybe not a big possibility, but possibly.
Second, there are inherent compromises to be made in the design of a two-prong AC mains adapter. My day job includes responsibility for field support and new design of a high volume 9V adapter designed expecially for guitars, and I've run into many of the issues that can happen. In a switching power supply, there is always some leakage. This is because by law the adapter must limit how much switching noise can go back out onto the AC power line, which effectively requires at least one capacitor between the Line and Neutral AC wires. This is to shunt RF noise, but it also lets some AC leak through. Generally this doesn't leak very much into the secondary, but there is capacitive leakage of some amount between every two conductors in the universe. The inverse square law makes this very small except for things that are close together - as they are in a compact AC power adapter. This is layout and construction dependent. In the day job, I have to worry about these kinds of issues frequently, and we sometimes make manufacturing changes specifically to address one or another odd problem in the field. It can be difficult to separate design problems from manufacturing defects from non-fatal component failures from weird real-world conditions.
I make a real effort not to mention our stuff on forums, as I'm in general opposed to using forums for advertising. I do sometimes when I think it's a possible technical solution. Can you PM me?
> before the ... um... mid 1960s. That was when conversion to three-wire was under way
"Mid 1960s" is spot-on for new US work.
Note that seadi123 is "in EU". While the addition of ground sockets happened in most areas at similar times, it happened different in, say, urban Switzerland and rural Portugal.
I was just looking-up and commenting on the US situation for someone. An excerpt:
Our new house in 1961 was 2-pin. 1965-1968 the NEC changed to require 3-pin grounded outlets in nearly all spaces, so most such work will be 3-pin and nominally properly grounded. Existing installations never need to be updated unless there is major rebuilding. All new venues (from taverns to bedrooms) should be 3-pin and the 3rd pin should bond back to supply Neutral and dirt-rods. But musicians are low-income and often found in old buildings, pre-1965 and never updated. This may run half the houses and buildings in many neighborhoods. Maybe more as far as musicians go.
First of all, i want to thank you all for the help ! My house and my neighbour's house (my uncle), were built in 50's and 70's. I'm pretty sure here in Albania(EU), nobody knew anything about three wires back then. Actually i'm pretty sure electricity was used only for the fridge and lights (Albania used to be under communism back then, we got our first Tv in '95). However, the elctrical stuff were re-done 15-20 years ago, to today's stadards i believe, but it's still probable that both mine and my uncle's house may have some defect or something. I will try in another house as soon as i get the chance, until then i'm wearing slippers whenever i play the guitar. The static noise however is unbearable. How about adding a 7809 regulator?
Local house grounding used to depend on metal water pipes going into ground. UK added a ground rod as the primary local earth a long time ago. Renewal with plastic water pipes can remove the connection if there is no "dirt rod".
The neutral should go to ground at the street supply transformer, but if this connection failed it may not be obvious to many customers and multiple properties would be affected.
When you have an ungrounded amplifier (ie. an amplifier where the circuit ground doesn't have a low impedance path to mains earth, you often get buzz problems. Normally the path to mains earth diverts the noise away from the signal lines but when the mains earth isn't there it finds a path into the signal lines.
If you can connect you amplifier ground to a mains earth then it will help a lot.
Things like PC speakers rely on the PC being connected to mains earth.
(The ground-lift switch on the old amps was to prevent ground *loop*s under assumption that there is a another point in the system connecting to mains earth. This is a different issue.)
Quote from: anotherjim on September 26, 2017, 02:37:55 PM
The neutral should go to ground at the street supply transformer,
I'm pretty sure at seadi123 house Neutral & Ground are tight together INSIDE building.. :icon_wink:
Quote from: antonis on September 27, 2017, 07:19:24 AM
Quote from: anotherjim on September 26, 2017, 02:37:55 PM
The neutral should go to ground at the street supply transformer,
I'm pretty sure at seadi123 house Neutral & Ground are tight together INSIDE building.. :icon_wink:
Yes. In the panel the neutral and ground are tied together. What comes in from the street are 2 lines, in the US they have 240 volts potential between them (Europe etc, 240V). The ground is what separates them into two 120V legs, the 'sides' of your electric box.
A power outlet has two wires and an earth. One of the two wires should be Neutral.
The neutral connects to earth at the house, which also connects to a ground stake poked into the ground.
The voltage you see at the power point is single-phase.
The single-phase derives from a three-phase star or Y connection, which has 4 wires.
The street normally has 4 wires. Your house might have two of four.
Further up the distribution system you only use three wires (there is no neutral) which is a three-phase delta connection. You convert from delta to star using a three-phase delta-star transformer.
http://www.ecmweb.com/sites/ecmweb.com/files/412ecm06fig1.jpg
https://qph.ec.quoracdn.net/main-qimg-0220fd65d02b4c6d48a809bb9f2c0d23
120V systems
http://www.neilorme.com/pics/deltawye_figure1.gif
240V system:
https://qph.ec.quoracdn.net/main-qimg-91d4688ec60d9cbab02471e38214ee57?convert_to_webp=true
You will notice that the voltages don't add in magnitude.
They add-up when you take the phase shift between phases into account.
Quote from: GibsonGM on September 27, 2017, 07:26:17 AM
Yes. In the panel the neutral and ground are tied together. What comes in from the street are 2 lines, in the US they have 240 volts potential between them (Europe etc, 240V). The ground is what separates them into two 120V legs, the 'sides' of your electric box.
You're right Mike but I've seen some old buildings with only ONE line coming from the street (actually from medium to low mains transformer) and that's the HOT wire..
(old school electricians used to call it "phase"..)
Neutral wire starts from main fusing panel where it's tied with Ground wire..
(there isn't any Ground wire inside the building - all sockets and other mains receptors are of 2-pin type..)
Sorry guys, but I ain't never seen a neutral used as or tied to earth in the consumer unit or fuse panel. Any Supply cable earth is not relied on at all or needed.
(http://www.electrolesk.com/Assets/Consumer-unit-wired2.jpg)
Here's why.
The input after the isolation switch/fuse should now go through a RCD breaker. This trips out if the current in the Live or Neutral differs significantly (20 to 30mA often). This will happen if either Live or Neutral connect to Earth. If the currents do differ, then some current is going somewhere else which must be Earth, since that path is completed back at the transformer by that Neutral connection. Can you see that if Earth and Neutral were tied together in the house, then this won't work properly? Also, this is why the main circuit breaker should be a double pole while the Load breakers only need Live side single pole.
Oh, and...
(http://www.electrical-engineering-assignment.com/wp-content/uploads/2014/02/72.png)
This is a good piece of info to read on the subject, and references the NEC. I'm not going to pee pee fight over where the gnd's connect in the breaker box...
https://diy.stackexchange.com/questions/1706/is-it-ok-to-have-mixed-grounds-and-neutrals-on-bars-in-a-breaker-box (https://diy.stackexchange.com/questions/1706/is-it-ok-to-have-mixed-grounds-and-neutrals-on-bars-in-a-breaker-box)
I 'get' what you are saying regarding SUBPANELS, Jim...having '2 grounds' can REALLY mess up your day, as the resistance between them is not trivial. Neutral must be isolated in a sub-panel. Are you not in the US? I have never seen a panel that looks like that, LOL!!! ;) Might be different laws/practices, too, perhaps?
I would not want to play with the old "one wire" system, antonis....!! of course it works, but wow...just so unfamiliar that something bad would be sure to happen :)
UK practice, which is the same as Europe (EU). We have a very lethal single phase around 230v rms and even more lethal 415v rms between phases of a 3-phase supply. So it could be that ours is a bit different to 110v countries.
I do sometimes wish that our AC outlets and circuit breakers all had double pole switching. With only the Live switched off, an accidentally earthed Neutral will throw the RCD and knock all your power off!
Fyi, this could also be a problem with the grounded prong of the 1/4inch connector inside the guitar and might need resoldering. The wires have prob become frayed/poorly connected. I had this issue before with a bass guitar resoldering the input piece fixed the problem grounding problem along with the buzz.
Jim, coming from UK I totally understand your consumer unit picture, I was a sparky years ago and am familiar with the 17th edition etc. I do have a hard time with USA wiring though, everything that has been explained to me about USA mains just sounds dangerous and hit or miss, they seem to have 2x100V lines and sometimes the earth is connected to the neutral.
Are there any USA sparky's here that would like to explain your system properly. It might be fun :icon_wink:
In New Zealand and Australia it is mandatory to link the Neutral and Earth bars together at the switch-board (as well as distribution transformer). MEN, Multiple Earthed Neutral. The reason is to provide a almost guaranteed low resistance for fault current and trip the breaker fast.
RCD's still work fine in this system, but are installed either on each circuit or one on every three breakers before the neutral(s) enters the neutral bar. RCD's and are also mandatory in modern installations here.
The high voltage, low current AC that can be present on switch-mode plug-packs as leakage can be fatal to electronics. Bitter experience.
> A power outlet has two wires and an earth. One of the two wires should be Neutral.
Not always.
I have learned that in Argentina they get fed Delta with ~~230V between legs, and this is what they feed their lights and appliances. *Neither* power wire is Ground or Neutral!
Ground (protective earth) is supplied (in newer installations), but is NOT sized to carry power currents. (Being two legs of a 3-phase, the line-to-Earth voltage is 127V.)
Stuff should NOT rely on either side of the line being groundy.
> I ain't never seen a neutral used as or tied to earth in the consumer unit or fuse panel.
Because you have only seen post-RCD systems?
Also because even before RCD, UK commissioning rules required a G-N high-volt test. In older CUs the sparky would remove the G-N jumper for this test. Today I see the G-N jumper is (by necessity) before the master RCD, which I also see is often outside the CU, near the meter. (I think you will evolve toward individual circuit RCDs, for the reason anotherjim mentions: one fault darks the whole house.)
> USA sparky's here that would like to explain your system properly. It might be fun
No. Every time I engage a UK tech on US/UK systems, it goes badly. BOTH rule-books are extensive, dense, arcane, and assumption-ridden. NEITHER of us can fully comprehend how it is done on the other side of the pond. The un-stated un-questioned assumptions lead to confusion, frustration, and irritation.
The US system is as safe as any other, safer than many. (If it were not, Canada would not be using 99% the exact same rules!).
The US system IS "victim" of history. We got into electric before good insulation was widely available. 100V seemed safer. Europe began electrification about the same time but not nearly as universally. Europe's lower installed inertia (and war losses) allowed (and demanded) safe use of more economic systems as improved insulation and plug materials came along in the 1930s and 1940s.
Neutral is "always" connected to Ground some-where. This is not a hard/fast rule, but a consequence of good practice and interpretation. WHERE the bond is (house, street) is not really our concern, because the wires are fat and 100'/30m one way or another makes little difference.
QuoteI have learned that in Argentina they get fed Delta with ~~230V between legs, and this is what they feed their lights and appliances. *Neither* power wire is Ground or Neutral!
Interesting, I've never heard of such a system.
Some equipment would struggle to pass EMC without a mains earth.
Quote100V seemed safer.
Probably a consequence of Edison's fear mongering.
US must roll-out a lot more copper.
The system we have in AU is 240VAC (I think they now call it 230VAC with asymmetrical tolerances) the safety aspects have been argued to death. There's good and bad sides to it. I must say the voltage and frequency here are pretty well regulated. The US on the other hand is renown for brownouts and voltage variations.
Most European electrification began for a specific use other than general power. Often hydro generation for a railway and sold to the area along the line to make a bit more money. Then the system & voltage was whatever the railways engineer had selected and could be DC.
Quote from: anotherjim on September 27, 2017, 02:37:14 PM
The input after the isolation switch/fuse should now go through a RCD breaker. This trips out if the current in the Live or Neutral differs significantly (20 to 30mA often). This will happen if either Live or Neutral connect to Earth. If the currents do differ, then some current is going somewhere else which must be Earth, since that path is completed back at the transformer by that Neutral connection. Can you see that if Earth and Neutral were tied together in the house, then this won't work properly? Also, this is why the main circuit breaker should be a double pole while the Load breakers only need Live side single pole.
That's exactly why you can't use RCD breaker in a consumer panel like the one I mentioned above.. :icon_wink:
(in your panel photo, delete all black lines, DP MCB breaker & blue button relay on RCD and use green lines as Neutral..)
So, main circuit breaker is a single pole (Hot/Live) and it works only for over-current protection..
(you can easily experience a nice electrocution untill main breaker "decides" to open..)
<I would not want to play with the old "one wire" system, antonis....!! >
Neither do I, Mike... :icon_biggrin:
(but someone have to be an authorised electrician engineer for upgrading such a mess so I can't fess up anything more in public..) :icon_redface:
I re-wired my entire house (it came with 1930s early cloth-covered 2 wire, mostly). Lucky for me (or IS it lucky??) where I live has no electrical codes; no requirement for inspection after you work. In that situation, studying 'how it's done' is a really, really good idea, such as on 3-way switching etc. Ultimately, if one is careful, it is MUCH better to have the new wiring than to leave the old...that's probably partly opinion, but I'll stand on it.
However, all that was required in my case was to remove wire runs and re-wire outlets, and for me to run a new line to my 2nd floor, which I wired as I constructed it. It was very easy, and didn't require considering things like "is neutral connected to ground?", as whatever was in the panel (a new panel a previous owner had installed...) remained down-stream of my work. Some runs were new and had ground, so I copied how they did it when replacing the 2-wire.
The lights work, the LED tester says the outlets are done right, and it has been fine for a year now. :) :)
> Probably a consequence of Edison's fear mongering.
> US must roll-out a lot more copper.
> The system we have in AU is 240VAC
Street to house, a bit more (but Aluminum). The main load is figured on 240V, same as yours +/-. There are however three wires, two full size and one usually full size or one size smaller. I have "100A service" as two 100A wires and a 80A support line; for 100A on single 240V you may have two 100A wires, about 70% of the total area used here. Supports and labor amount to about as much as the wire, so the cost difference can't be huge. (+/- local costs of Aluminum.)
It IS true that Tommy found fewer dead workers around <100V machines than >100V machines. This decision was set *before* the AC/DC wars, he was just selling juice. However the danger rises rapidly above 100V, and for economic reasons (size/cost of Copper) we have snuck-up 1/4 Volt a year to 125V area.
GFI (RCB) has been a big help for frayed wires around dirt and concrete.
> Some equipment would struggle to pass EMC without a mains earth.
The Argentine system has a PE. But neither Live wire is earthed. Good equipment *should* do fine this way. Similar to the German plugs, where you can't know which of the two power wires is more groundy.
> US on the other hand is renown for brownouts and voltage variations.
That is not my general experience.
At my workshop, voltage was a solid 117V unless I pulled a large load (I was on the far side from the PT). *Except* one year a backhoe ate one of two feeders into the city. We lived on a steady 109V for a while.
My last house was 128V, I called and complained, got a 124V which never varied. (I believe it had been over-tapped for an older feeder, which was replaced just before I bought the house.)
My current *house* sags, yes. But if my load is light, the voltage is *always* 125V solid. On heavy load I can dip below 110V, but my calcs on my too-long feeder say this is almost all in "my" wire (1% in transformer). I believe the wire was installed for a trailer, and never upgraded when the house was built. I can ask Hydro for a re-study, but they give the first 100 feet free, the rest would be my investment. Not worth it.
The US and the UK can't be quite compared, because the US grids are MUCH larger than the UK grids. Both in power and in distance. I am reading B.M.Weedy's classic book, primarily UK but with notes on the US, and it is apples to watermelons.
There *are* areas of the US where voltage is wonkier. And yes there have been supply shortages forcing cut-backs etc. Some of this is dying industrial cities which can't afford maintenance. Some has been really stupid government rate policy which invited suppliers to "game the system" to force artificially high rates. But many areas are as bad. Puerto Rico (of the US but not in the US) has been an economic disaster even before the recent storm. Brazil IMHO mis-prices its electricity for political favor. India tolerates massive stealing, again probably to prevent public outrage.
Quote from: PRR on September 28, 2017, 10:30:17 PM
> Probably a consequence of Edison's fear mongering.
> US must roll-out a lot more copper.
> The system we have in AU is 240VAC
Street to house, a bit more (but Aluminum). The main load is figured on 240V, same as yours +/-. There are however three wires, two full size and one usually full size or one size smaller. I have "100A service" as two 100A wires and a 80A support line; for 100A on single 240V you may have two 100A wires, about 70% of the total area used here. Supports and labor amount to about as much as the wire, so the cost difference can't be huge. (+/- local costs of Aluminum.)
It IS true that Tommy found fewer dead workers around <100V machines than >100V machines. This decision was set *before* the AC/DC wars, he was just selling juice. However the danger rises rapidly above 100V, and for economic reasons (size/cost of Copper) we have snuck-up 1/4 Volt a year to 125V area.
GFI (RCB) has been a big help for frayed wires around dirt and concrete.
> Some equipment would struggle to pass EMC without a mains earth.
The Argentine system has a PE. But neither Live wire is earthed. Good equipment *should* do fine this way. Similar to the German plugs, where you can't know which of the two power wires is more groundy.
> US on the other hand is renown for brownouts and voltage variations.
That is not my general experience.
At my workshop, voltage was a solid 117V unless I pulled a large load (I was on the far side from the PT). *Except* one year a backhoe ate one of two feeders into the city. We lived on a steady 109V for a while.
My last house was 128V, I called and complained, got a 124V which never varied. (I believe it had been over-tapped for an older feeder, which was replaced just before I bought the house.)
My current *house* sags, yes. But if my load is light, the voltage is *always* 125V solid. On heavy load I can dip below 110V, but my calcs on my too-long feeder say this is almost all in "my" wire (1% in transformer). I believe the wire was installed for a trailer, and never upgraded when the house was built. I can ask Hydro for a re-study, but they give the first 100 feet free, the rest would be my investment. Not worth it.
The US and the UK can't be quite compared, because the US grids are MUCH larger than the UK grids. Both in power and in distance. I am reading B.M.Weedy's classic book, primarily UK but with notes on the US, and it is apples to watermelons.
There *are* areas of the US where voltage is wonkier. And yes there have been supply shortages forcing cut-backs etc. Some of this is dying industrial cities which can't afford maintenance. Some has been really stupid government rate policy which invited suppliers to "game the system" to force artificially high rates. But many areas are as bad. Puerto Rico (of the US but not in the US) has been an economic disaster even before the recent storm. Brazil IMHO mis-prices its electricity for political favor. India tolerates massive stealing, again probably to prevent public outrage.
You're Right about Brazil. Electricity prices here are a bit unrealistic.
Our system is sometimes similar to Argentina's, with two hots, no neutral, and an earth. Problem is, in more than 90% of buildings (including my house), The earth pin is simply left unconnected to save on wire.
I Said "sometimes" because it's not a sure thing. Some cities are "220", two hots and no neutral, only ground. Other cities are "110", meaning hot, neutral and Ground. Anything sold here that needs mains Power Must have a 110/220 switch. If you take your valuable 110V tube amp, go gig on a 220 Town and forget to Flick The switch, you WILL fry your amp.
There's absolutely NO inspection of New (or old) installations, so people just do what they want.
If you add The "I'm too lazy to ground my wall sockets" state of mind to The equation, you can start to understand why so many Brazilian guitarists still die from electrucution when they are holding the strings and grab The microphone...
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QuoteIt IS true that Tommy found fewer dead workers around <100V machines than >100V machines. This decision was set *before* the AC/DC wars, he was just selling juice.
So there is a reason for it.
Quote
However the danger rises rapidly above 100V, and for economic reasons (size/cost of Copper) we have snuck-up 1/4 Volt a year to 125V area.
I've always wondered what the average (US) man in the street thinks mains voltage is; I've seen 110V, 115V, 117V, 120V. The nominal voltage for consumer equipment seems to vary; maybe not nowadays. I used to think it was simply different areas ending-up with different voltages due to loading effects. It was a problem designing power supplies for US which used transformers.
QuoteMy current *house* sags, yes. But if my load is light, the voltage is *always* 125V solid. On heavy load I can dip below 110V, but my calcs on my too-long feeder say this is almost all in "my" wire (1% in transformer).
I've came to the exact same conclusion in my house, the drop is in the house wires. I can't quote the voltage drops because I rarely have to check it. In general the street voltage is 240V, despite the now 230V rating.
QuoteThat is not my general experience.
Interesting. That's not what I've read over the years. Maybe things have improved.
QuoteThe US and the UK can't be quite compared, because the US grids are MUCH larger than the UK grids. Both in power and in distance. I am reading B.M.Weedy's classic book, primarily UK but with notes on the US, and it is apples to watermelons.
It's enormous! and so many vendors. We have large distances here but the larger loads are distant.
Has anyone is South America noticed small shocks from equipment with a mains earth pins? especially things with metal cases and panels. Some equipment, like desktop PCs etc, use the ground return for line-filters.
Not connecting the earth line is in effect like operating the equipment with a single fault (ie. no earth)
so if you do get a second fault the equipment might not be safe.
UK system was worked out during 1940's during WW2 to cater for the intensive rebuilding foreseen after bomb damage. 240v chosen to cut copper weight, also the use of ring wiring (every outlet has 2 cables for east and west connection to the fuse/breaker).
I've been pondering our reluctance to bond Neutral to Earth at the property. I guess UK engineers have it set in stone that Earth is for protection against exposed Live surfaces and it should do nothing else. However, one of the worst fault conditions is the 3-ph transformer Neutral feed breaking open somewhere downstream, although ground at the transformer can be expected to remain good. That allows interaction between all 3 phases according to load and the Live-Neutral voltage at a property can be anything from 0 to 415v. I suppose this "floating neutral" condition is mitigated if your Neutral is individually grounded? A danger of this is, as the Earth bond is only in a little part made of wire, large currents passing via Earth can cause a voltage lift at your Earth rod, and it isn't a safe 0v any more.
Quote from: Hatredman on September 28, 2017, 11:51:31 PM
If you add The "I'm too lazy to ground my wall sockets" state of mind to The equation, you can start to understand why so many Brazilian guitarists still die from electrucution when they are holding the strings and grab The microphone...
I'm pretty sure these "happenings" are strongly encouraged by Brazilian Drummers Federation.. :icon_redface:
> what the average (US) man in the street thinks mains voltage is; I've seen 110V, 115V, 117V, 120V.
Voltage is invisible. The average man has NO idea. Not counting pro electricians, I can only think of one guy I know who could figure it out, and he doesn't care.
As I said, the historic trend runs to 1/4V rise a year. In the 1930s it was around 110V, and the number lingers. 1960s saw more like 117V, another lingery number. Nearly all recent incandescent lamps (before they went out of favor) were rated for 120V. Filament lamps are by far the fussiest loads. 5V low and they run dim, 5V hot and they burn out too fast. I assume nearly all US homes had 120V (117-123) in the 2000-2010 period. Recently 123V-125V (no load) seems common. Sag is actually specified (if not enforced) and may be 3%-6% in most houses at 1/2 to 3/4 load. (My 15% sag at half rated load or max ordinary load is unusual.)
> the drop is in the house wires.
Should be 2% in the transformer if you and all your neighbors on the transformer are pulling heavy load. Drop-wire loss depends a lot on set-back: 500 feet (me) is too far, 20 feet (cluster housing) opens problems with short-circuit fault current magnitude.
> so many vendors. We have large distances
I thot the UK grid was mostly nationalized? In the US, very little; but the various players mostly cooperate on technical workings.
Glasgow to London is 340 miles. St Louis to Boston is 1,230 miles, but 1,500 miles the way the large wires run (through Canada!).
> reluctance to bond Neutral to Earth at the property
As long as it IS bonded, somewhat nearby, I call it equal. In my cellar, at the meter, out on the street (though at 500 feet back from street, I already have significant difference due to earth current and line-drop).
Dirt-bonding may be a lot to do with protecting the street gear. Lightning happens. Good dirt-rods localize the damage. In the US, the utility's problems and the user's problems are two very different authorities; the UK may take the tack that if the utility is good, the users should be OK. And while I am not hip on utilities finding all problems in their dirt-rods, they gotta be better than the average user who does not know about a dirt-rod.
I too have pondered. One BIG fault in the US electric implementation is that devices (outlets, switches) are not required to be High Temperature material. In very old devices it was not an issue: many devices were ceramic and some paper-insulated lamp sockets were allowed to burn-up. But the rise of cheap plastic is now a plague upon our system. It is very common for overloaded outlets or multi-way strips to arc and burn with enough energy to ignite the house. In fact early "Arc Fault" breakers intended to mitigate this apparently really sensed the increased leakage of half-melted plastic. It also means our "#12" wire, which would take 25 Amps easy and is used at higher current in non-house wiring, can only be used as 20 Amp stuff because the devices can't take the temperature. We are stuck with the billions of installed devices for at least the next 50 years.... but why aren't we forcing better devices now, instead of the dubious Arc-Fault breakers?
Uk grid is privately run with multiple private "suppliers" who are the ones who take your money. A government regulator is supposed to keep them in check.
For all of the regulations that installers are meant to work to, does nothing for the quality of the equipment on the market. We have pendant lamp sockets that can't stand the heat of anything hotter than a 40w filament lamp (filament lamps are supposed to be banned here anyway). Socket strips with spot welded busbars that fall apart. Screw terminals that can't reliably clamp more than one wire and held in plastic walls that crack if you tighten the screws a bit too hard in an attempt to actually grip all of the 3 wires you have to fit in it.
Quote from: PRR on September 29, 2017, 10:56:54 PM
> what the average (US) man in the street thinks mains voltage is; I've seen 110V, 115V, 117V, 120V.
s I said, the historic trend runs to 1/4V rise a year. In the 1930s it was around 110V, and the number lingers. 1960s saw more like 117V, another lingery number. Nearly all recent incandescent lamps (before they went out of favor) were rated for 120V. Filament lamps are by far the fussiest loads. 5V low and they run dim, 5V hot and they burn out too fast. I assume nearly all US homes had 120V (117-123) in the 2000-2010 period. Recently 123V-125V (no load) seems common. Sag is actually specified (if not enforced) and may be 3%-6% in most houses at 1/2 to 3/4 load. (My 15% sag at half rated load or max ordinary load is unusual.)
Ah, the invisible hand of Georg Ohm. What most people don't consider is that they and their neighbors form a distributed and highly variable load. This load drags down the voltage on the power lines leading to them. It's less easily observable in metropolitan areas, but out here in the sticks, if everyone's AC is humming HARD and Tom is out in the barn welding while Betty Lou is inside cooking a roast in the electric oven while drying clothes in the electric dryer, things sag a bit near them. Especially if Fred is welding and Linda Lou is cooking and drying in the AC'd house just next door. I happens to be September or October and although it hits 80-90 in the afternoon when this is happening, but about 6:00, the laundry is done, the roast is done, and the welding is over and it drops back to the mid 70s and the ACs start cycling off. The family's TVs go on and have an AC line voltage that has bounced to 135-140 because the power grid sees a massive drop in overall power. The grid has to react and takes some time to get regulated back down. In the morning, the same happens, but in reverse. The utilities actively manage for sag and bounce, but can't fix it everywhere instantly. Long wiring lines make this even worse. And in the country, lines are looong.
There is some benefit that might happen in an isolated house to buying a whole-house ferroresonant transformer. They're big, loud, and heavy, but if you do that, you get tightly regulated power over a wide range of input voltages.
Quote
> reluctance to bond Neutral to Earth at the property
As long as it IS bonded, somewhat nearby, I call it equal. In my cellar, at the meter, out on the street (though at 500 feet back from street, I already have significant difference due to earth current and line-drop).
Dirt-bonding may be a lot to do with protecting the street gear. Lightning happens. Good dirt-rods localize the damage. In the US, the utility's problems and the user's problems are two very different authorities; the UK may take the tack that if the utility is good, the users should be OK. And while I am not hip on utilities finding all problems in their dirt-rods, they gotta be better than the average user who does not know about a dirt-rod.
I have a dirt rod at the pole, about 50 feet from the garage; one at the garage; one at the east end and one at the west end of the house. I also have massive transient clamps at the garage, and each end of the house. When we moved into the house, we had only the dirt rods and lost a $200 smart thermostat about once a year. As the saying goes, the first four times that happened, we thought it was a random accident :icon_lol: then I got serious and started spending money on transient protectors and not thermostats. Haven't lost a thermostat since. Also since then, the local electrical utility company has updated their lines to thicker, higher current and higher voltage transmission lines which in turn reduce sag and bounce.
It is quite difficult for the average Joe, Fred, Jane or Frieda to know enough about this to make any kind of decent decisions about it.
> they and their neighbors form a distributed and highly variable load.
Thanks for detailing your situation.
"All": somewhere I had a hint where R.G. lives, and peeked in Google Maps. Except for the trees (many here, few there), we live in "similar" places. The low-tax district outside a minor town. Ex-agricultural land (logging here, grazing and farming there) re-purposed for low-density houses when house-tracts became more profitable than logs/cows.
Yes, the wires are l-o-o-o-o-ng.
Longer than they "need" to be. Here, and I think near R.G., a big transmission line runs high above woods/fields, going somewhere else, not tapped to local loads.
Nevertheless, details (like Ohm) matter. My street seems to be 125V SOLID. I have both Volt and Amp meters in my cellar, so I know when I am low-load and can estimate my hi-load drop. It always works out to 125V at the street- no, one hot day last summer it was 123V all afternoon.
This despite the fact that our neighborhood lines are not built-out. There's 3-phase around the peninsula, but only 2 transformers each end of the loop, on a platform sized for 3 cans. My crossroad is one phase. They could add the missing transformers and run 2 more lines over my road. All this was done 35 years ago. They musta been told there was going to be a huge housing boom out here; didn't happen, because even the minimal network appears to give low-low losses.
Three near neighbors and I have arc welders, though we have switched from the big tombstones to modulated switchers, and don't do 48" pipe.
OTOH, I do know places the farmer put up a wire, tapped it when he sold 5-acre sub-plots, and when that burned down the local utility bought it out but did minimal upgrading. Everybody on the line knows when your well or dryer starts.
> It is quite difficult for the average Joe, Fred, Jane or Frieda to know enough about this
Indeed.
> lost a $200 smart thermostat about once a year.
For a while I was hoarding mercury thermostats--- never fail.
The $69 Honeywell serves fine for 3-4 years-- we are not thermo-geeks.
In another place I was losing a modem or two every summer. The place was once overhead power and phone, they put in underground wires, but only the power was moved-over. Lightning tickled the overhead phone, passed out the underground power..... THROUGH my modem. For a while I had a knife-switch to break the phone line when not using the modem. Finally a BIG hit took out the antique telco protector block, the telco guy did a "WTF?", and switched the phones over to the underground line that had lain idle. No more trouble after that.
One more issue with measuring voltage: the voltage is rated as the RMS (root mean square) voltage which is the equivalent DC voltage that would cause the same heating when driving a resistor. But people tend to use peak-reading meters calibrated in RMS values. All is well until the waveform changes from pure sine to something a bit more ragged like the glitch that occurs with some fluorescent lights above and below the switching point and various loads like switching power supplies. Then the meter needs to be a true RMS rather than a peak-reading meter calibrated in RMS. I get 121 VAC in my area in Mississauga but the peak-reading meter may be responding to changes in waveform as much as voltage. So I really don't know what I have, nor do most people even if they have a typical DVM.
Older DVMs tended to read the Average.
Nowadays "True RMS" is fashionable.
I assume you have the bench chops to make a few wave-forms to see what your meter calls it. (We are of course getting very far afield of that Average Consumer.) Aside from peak-catchers and spike wave forms, quite large differences in shape make smaller difference in measured Avg/RMS voltage.
It has been so very long since I had a 'scope on a power line (through say 120:6V transformer!) that I do not know if they can have significant spikes routinely. (Unless there is a tombstone welder on the line.) It takes large energy to spike-up a utility supply.
Quote from: amptramp on September 30, 2017, 09:58:28 PM
One more issue with measuring voltage: the voltage is rated as the RMS (root mean square) voltage which is the equivalent DC voltage that would cause the same heating when driving a resistor. But people tend to use peak-reading meters calibrated in RMS values. All is well until the waveform changes from pure sine to something a bit more ragged like the glitch that occurs with some fluorescent lights above and below the switching point and various loads like switching power supplies. Then the meter needs to be a true RMS rather than a peak-reading meter calibrated in RMS. I get 121 VAC in my area in Mississauga but the peak-reading meter may be responding to changes in waveform as much as voltage. So I really don't know what I have, nor do most people even if they have a typical DVM.
I'm glad this was brought up, I almost asked about it the other day. My meter is a Fluke 73, it's not true RMS, so I always figured the AC readings were probably incorrect. I don't have a scope or signal generator to conduct my own tests.
FWIW, I just read 123.8 at my wall socket. It's nice and cool outside, so nobody is running AC, and probably most are asleep.
For those lacking a true rms meter, but lacking the funds, Analog Devices AD8436 is availble in a SOP package for $11 from Mouser; the LTC1966 is available for $15 from Digikey, and uses an internal A-D conversion and computation of the RMS value, so it has low and constant errors over its whole range. You'll need a suitable attenuator/divider as they only take in aboutu 3Vrms without damage, and some damage control parts for when you set the divider wrong, but you could conceivably make one of these as an add-on to your multimeter for $30-$40.
However, the AC mains line is never far enough from a sine wave to make all that much difference. If you're measuring square waves or sawtooths, yeah, you need true rms. Doesn't happen all that often.
QuoteVoltage is invisible. The average man has NO idea. Not counting pro electricians, I can only think of one guy I know who could figure it out, and he doesn't care.
Thanks, I've learnt something here. That's an eye opener for me.
QuoteI thot the UK grid was mostly nationalized? In the US, very little; but the various players mostly cooperate on technical workings.
I'm in Australia.
QuoteHowever, one of the worst fault conditions is the 3-ph transformer Neutral feed breaking open somewhere downstream, although ground at the transformer can be expected to remain good. That allows interaction between all 3 phases according to load and the Live-Neutral voltage at a property can be anything from 0 to 415v. I suppose this "floating neutral" condition is mitigated if your Neutral is individually grounded? A danger of this is, as the Earth bond is only in a little part made of wire, large currents passing via Earth can cause a voltage lift at your Earth rod, and it isn't a safe 0v any more.
I guess a break like that isn't good in any system.
As a kid I was fortunate enough to see the insides and workings of many factories. Neutral currents are considered bad. Most factories use three phase equipment and any imbalance of the phases is a sign of a fault. There's been a trend here over the last 25 years to so for houses to be single phase. This is done for costs but also so the authorities can juggle the loads on the phases balance the phases. Statistically if you juggle enough houses you can ensure the phases balance despite individual residence doing different things.
As for safety the different systems present different issues under different faults. All houses here have a neutral connected to an earth stake at the house. There is no ground wire along the street. The wires are three-phases and a neutral. The next layer up in the system drops the the neutral.
Having the earth connection at the house means you are likely to get the *highest* shock current if you touch the active because the impedance from the ground where you stand to the ground stake is relatively low, unless you live in apartments. There's a good chance it will pop the RCD every time however we have had this system long before RCDs were on the radar.
I'm not sure if the street wires have both neutral and earth in the UK? If you touch active in the UK I suspect you will get less of a shock than here because the ground impedance from the point where you stand to the earth stake is more distant. However, it is variable depending on where you live.
A lot of discussions here about our earthing system often indicates is creates a shock hazard, and it does, however it also prevents hazards in other cases.
Here's a paper with some arguments. Unfortunately is has a bit of bias to hospital systems.
http://www.sciencedirect.com/science/article/pii/S0004951414607601
> *highest* shock current if you touch the active because the impedance from the ground where you stand to the ground stake is relatively low
Insignificant. A "poor" ground is 100 Ohms. Your body is 100K down to 1K when wet (such as after a tingle begins to break-down cell walls). 1K in you through 100r in grounding, you still get 90% of full voltage.
To be safe under this theory you want ground resistance much higher than body resistance, say 1Meg. That does not happen in real life even if you try. (Yes, in a lab, maybe a hospital, you can stand/lie on a glass sheet. But in the real world everything leaks.)
We don't distribute a Neutral or an Earth until after the "street" transformer. 3 supply voltage phases are rotated along a route so adjacent properties single phase is different from their neighbours. Single phase feeder cables are LN + Steel Armour. The armour should only be connected to Earth from the supply end.
...But... Multiple Earth-Neutral bonding is coming in here too. And we have Gutshots!
This is what a UK utility may now install at a single phase property...
(http://www.marshflattsfarm.org.uk/wordpress/wp-content/uploads/2013/12/IMG_0352-SCALED.jpg)
The incoming black (lower left) has had its armour cut back below in the gland. It looks a bit thin but the Brown & Blue "Meter tail" wires are a standard one-size-fits-all. Anyway, zoom in to read all the labels. Over the Neutral at the fuse/link is a cover with a "PME" label. That's Protective Multiple Earthing. It would seem that it's up the domestic installer to make any earthing connections to that.
Here's a 3 phase PME with the domestic earth installed...
(http://www.isoenergy.co.uk/images/3phase-fuses.jpg)
There are a mess of standards here. Incoming fuses have the old UK Red-Yellow-Blue phase colour spots. Standard Brown meter tails used have had to be labelled to current standard as L1, L2 & L3. Outgoing phases from the MCB are the new (EU) colours. Brown=L1, Black=L2 & Grey=L3. I think the odd white fuse/link is a Neutral test point.
Note that the Yellow/green Earth wire is not from the incoming supply cable.
QuoteInsignificant. A "poor" ground is 100 Ohms.
I suspect that is the case. In anotherjims case the earth point could be 500m to 1km away but it probably doesn't affect the ground resistance.
QuoteOver the Neutral at the fuse/link is a cover with a "PME" label. That's Protective Multiple Earthing.
I wonder why they have decided to change after all these years. Maybe your old system is prone to a single point of failure and ground conditions.
> In anotherjims case the earth point could be 500m to 1km away
Wow!
OK, that's "only" 1 Ohm or less. Because "earth" is an indefinite thing, I have no objection.
That is IF the power company does NOT have "neutral return leaks". They shouldn't. It is bad practice, and normally poor profit. (I am ignoring an odd Aus system which has no metallic return; I assume it is rare even there.) Every few years in the US, some power company "loses" a Neutral, or has obscene unbalance, and many Amps flows through the dirt. Then the "Earth" in a cable from 1km away could be many Volts different from the dirt at the house. Touching an "Earthed" electric box and the dirt could be a good tingle.
Out here in rural Texas, often the feeder to one or another section of property (note here that "section" has the technical meaning of "one square mile") will be fed with a single hot line at ?? 13kV?? and feed transformers with a hot and earth ground. Accordingly, it's important that the "ground" at the transformer not be too far away from real, earth ground. This is at least partly accomplished by a thick bare copper wire running down the power pole and stapled in a spiral on the bottom of the pole before the pole is erected. At the low currents enforced by the multi-kV voltages, the volts per foot drop on the copper is negligible.
That is until the copper ground wire opens. So every pole has a copper ground wire. It forms a distributed ground connection that makes the real earth impedance quite low.
That is until another joker decides that the scrap price of copper is so high that they will steal air conditioner coils for their copper coils, copper wiring of any kind, and in particular, several people have been electrocuted, their bodies found next to the copper wire they were attempting to pull off the power poles. Not only are there harsh legal penalties (less harsh than death, anyway) but metal scrap yards now have to have positive identification, perhaps more than one form to accept scrap copper at all. It's so bad that in the Central Valley in California, people have been caught tying the electrical lines running out to the irrigation pumps to their pickup bumpers and driving off the pickup, copper wires trailing. I guess it's good that the people's republic of California fights hard for eliminating guns so guys like that can't get shot while committing their little misdeeds. But I digress.
Fueled by the enormous rise in demand for electronics, copper is rapidly becoming so precious that we'll probably see initiatives to prevent its use for electronics. The motivation is too great.
Here in Maine, someone broke the fence on a *sub-station* and managed to take all the copper without being killed. (Suggests insider training.)
Yes, axing the copper off poles is popular here. When I bought a house this year, I went to both adjacent poles and checked. They looked grounded last week.
Yes, some ID is needed to sell copper. To sell copper pipe scrap I needed my driver license and had to take a check (paper-trail). I think specifically for pole-length wire in a gauge range, the offerer SHOULD be required to show a Work-Order, a Disposal-Order, and payment direct to the utility; but there's a considerable run of private lines which "could" be salvaged by the owner.
One of the wire companies is selling "branded" wire. Stamped in the wire every few feet is Your Company Name and a running number so you can track where it was installed (stolen from). This would go with a stern letter to scrap dealers not to take such wire without ample documentation. I dunno if it has caught on. What I saw was just pole-bond, but I found span-wire (http://www.southwire.com/distribution/ProofPositiveCopper.htm) of similar idea.
The price of Copper is up. But the surge in theft seems to be driven by drug users. A 2007 study blamed crystal meth, but I am sure it makes very little difference.
Pole bond wire *could* be steel. It would have to be fatter, but space is not critical. Steel is cheaper than copper. Also harder to cut. Corrosion can be controlled with thin copper coat over steel (CopperWeld), though this "looks like" copper enough to fool a druggie.
All of this mostly protects the utility company equipment from lightning. For indoor non-concrete playing, low hum mostly depends on G-N bonding, not bonding to dirt.
Last apartment, about six years ago, woke up and the TV was out. Upstairs and downstairs. What the hell? Went outside, and somebody had chopped the exposed coax, maybe 15 ft at the most. What's that worth as copper scrap? 25 cents? How much meth can you buy for that?
Air conditioner at the guitar store has been hit several times. Landlord finally built a 2nd story platform for it.
Damn junkies.