Note on grounding, for beginners and especially those who live in Denmark/E.Euro

[Skruffyhound]

     I have eliminated almost all hum for all of my pedals by adding proper/better grounding (earth). All countries have slightly different systems but in Denmark they are not very interested in earthing stuff. I had naively assumed that the 3 pole socket, my power supplies were connected to, had an earth. Nada.
     After checking some equipment at work, I became curious, because all the sockets I checked there were without earth. So I went home and popped all the sockets open. Surprise surprise, no earth.
     I know that in many East european countries the "0" phase or neutral (blue wire) is used for earthing for power surges etc. but I had thought it was cheap solution. Even with double isolation on most household equipment there is still a measurable charge carried in the outer casing, i.e. if you stick your tongue on the un-earthed washing machine you will get a jolt (believe it or not we have had this problem in our Latvian house)
     Anyway, this seems to explain why my fancy pedal power supply wasn't cutting it, and incidentally why I get a strange prickly sensation on my wrists while operating certain equipment around here, I am carrying a little current.
     I ran a wire out to a radiator pipe and back to my power supply. Humming gone.
     
     Of course if you gig a lot, it may not be convenient to carry a 3 foot earthing stake with you and hammer it into the floor of the venue, but perhaps a length of cable and a big crocodile clip to the nearest radiator.
     I am no electrician, perhaps some of the educated forum members can clarify why this situation exists, or give a better work around, I just know that even my high gain pedals are relatively silent (hum wise) now.
     
    As always take extreme care with mains AC, check during daylight hours (so you can see what you are doing) and turn off the power at the main  power inlet for your home, before opening any sockets.

[frequencycentral]

Of course if you gig a lot, it may not be convenient to carry a 3 foot earthing stake with you and hammer it into the floor of the venue..............

Wot? Gig without my stake and hammer? No way! Forget the earthing - pretty sure at least half the audience were actually vampires at the last venue I played.........

[Skruffyhound]

Thankfully being a lousy guitarist shields me from the risks you gigging guitarists run.

[amptramp]

I assume everything is grounded through your amplifier.  If you have no ground, the capacitance distributed across the input winding of the power transformer will act like a concentrated capacitance at roughly half of the line voltage (depending on what part of the winding closest to the core) going to the transformer core, which is usually at chassis potential.  So in Europe, if you have a 220 VAC input line, you will have the chassis floating at 110 VAC with whatever current the capacitance will carry.

Some amplifiers have a capacitor on one input lead with an SPDT switch to connect it to one side of the line or the other.  However, the switch position that reduces the noise is probably the worst position for safety.

[Skruffyhound]

         Thanks for that information, I was not aware of that.
         However, since I am mostly nerding at home, and I get home after 9pm most days, I generally can't use my amp and rely on a Carl Martin "Rock Bug" to drive headphones. The Bug runs on 9v, so it's not any help.
         There must be quite a few people in this position.
         I have a Phil Jones cub-100 amp (primarily for acoustic) which I am very pleased with, but I can't say I notice that it cuts down on pedal noise the way you suggested. I will try and A/B test it a bit more closely with the Bug.

         Good to know someone has thought about this though

[Thomeeque]

...
I know that in many East european countries the "0" phase or neutral (blue wire) is used for earthing for power surges etc
...

I'm not electrician either, but my believe is, that here in Czech Republic they have to install independent grounding at least for 20 years already. And even before that, when one wire was used for both neutral and ground poles, it was always grounded somehow (so you would not measure any significant potential between ground pole of wall socket and radiator)! So it seems pretty weird to me what you say about Denmark.. We have sister company there (in CPH), I'll ask some colleagues about it (they should know, they develop and build some electronical equipment there).

How old is the house you live in? And the one you work in?

T.

[Skruffyhound]

Hi Tomas,
               my apartment is relatively new, from the 80's, the theatre where I work was built in the 1800's. The theatre has been regularly updated however, although we have layer upon layer of infra structure, nothing was ever pulled out, just new stuff wired over the top of it. Obviously all our 380Vac 32A /16A outlets have earth, and there are even two separate systems (old and newer) for sound equipment, a kind of filtered grounded supply to avoid interference from light circuits etc. However, both in my house and workplace, there are just a lot of normal power sockets with no ground.
               I could understand if there was a third (green/yellow) wire connected at the socket, which then was just connected to "0" phase at the main inlet, but there are just live and neutral. So the earth terminal of the device has nothing to connect to.
               Our Latvian house is out in the countryside and is wired with earth (now that I've replaced all the old wiring) but the only thing to earth to is "0" phase, this phase is then connected to an earth stake out in the fields. Even though there is a form of earth, our washing machine repair guy pointed out the charge in the casing of the machine and we measured it with a multimeter. He suggested I make a more serious earth connection myself in case our twins (1.5 years then) licked the machines.
               I don't understand enough about all this to see the difference between earth and neutral. In all our pedals ground is the casing, so presumably one could just connect the earth terminal to neutral and get the same effect as grounding to a radiator. In fact the earth terminal for pedal building is neutral! Obviously this only applies to  very low voltage/amperage, in high volt/amp devices presumably the earth as a safety measure draws current away from a faulty device's casing by offering an easier route than earthing through me.
               What about noise/hum though? Is there an advantage in having a true earth connected to the circuit, or is it enough to have a relative earth as I think Amptramp is saying.
               This has been bugging me for a while now, I'd like to understand these principles better.
                 

[wavley]

Of course if you gig a lot, it may not be convenient to carry a 3 foot earthing stake with you and hammer it into the floor of the venue..............

Wot? Gig without my stake and hammer? No way! Forget the earthing - pretty sure at least half the audience were actually vampires at the last venue I played.........

Completely unrelated but I did see the drummer of Don Caballero come out with a hammer and nails and proceed to nail his drums to a very nice hardwood stage once

[Skruffyhound]

Very pragmatic