Adapt or die - Where is Earth?

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mafioso

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Hi

I've been re-arranging the deckchairs to make room for another piece of equipment. One thing lead to another and I decided to clean all ac connections while I'm about it. Everything was switched off, unplugged and the mains switched off at the board of course.

The room is where I do needlework and is a bit of a nightmare as there is only a single wallplug. Before the needlework, the room was always a workroom and many years ago, I used metres of the thickest available cable and extended the single wall outlet, circling the smallish room by about 80% of its circumference and added two additional surface mount wall sockets.

Obviously, 3 core cabling was used and I made sure live, neutral and earth was correctly orientated and the all important earthing was maintained to the two surface mount ac sockets by means of 3-core cabling.

Although there are several pieces of equipment always plugged-in (like 4 amplifiers, two pre-amps, two tuners, a 'scope, 3 turntables and my computer) it is still a highly undesirable state of affairs which I can't do much about.

Only my computer, its scanner and printer is always on...plus for example 1 turntable, 1 amplifier and pre-amp and perhaps the oscilloscope - still a bit borderline for my taste and a single wall outlet, but again, there's not much I can do about this for now.

This afternoon, I started cleaning ac connections at and inside the wall outlet and must admit I haven't looked inside these things for a while.

My stupid question: Where is earth as there seemingly is nothing connected to the earth pin's receptacle at the top? Is the receptacle for the fat earth pin inside the wall socket connected to the wall outlet's metal body, which is bolted to the outlet's metal wall housing/ which is plastered into the wall?

I must admit there is a bit of an ulterior motive asking this question.

After re-arranging things to find space for the Dynaco amp, turntables and pre-amps were moved and I had a fair bit of hum. After moving things and re-routing cables, things are almost back to peace and quiet, except for a puzzling phenomenon which in my book spells DANGER.

If I touch metal parts of plugged-in (but switched-off) equipment, I can feel a slight 'buzzing' through my fingers.

As I write this, I have just unplugged the Dynaco from the mains and could detect no buzzing touching metal bits. Next, I plugged it in without switching it on. Still no buzz.

Then, I switched it on and as the valves warm up, the buzz is back on for example a tuner's antenna (connected to the Dynaco), a turntable's metal armlift device (connected to the Dynaco) and the connecting phono leads' earth return bits.

There is no audible hum now and the little valve integrated plays nicely, but it looks as if it is injecting some ac leakage into all systems connected to the ac power line and into all the other equipment connected to this line.

It is of course to be expected that the Dyna cannot possibly be in topclass and electrically safe condition after all the years since 1964. I'll just have to 'hold my horses' for now and stop using it in the interest of longevity, i guess...or move to the Pretoria area ;D

mafioso



 
 

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