10 metres audio cable going into PC = too long?

Eiron spake thus:

Some of us may be more sensitive than others. It's a subjective thing, after all. Believe me, I felt *something*. Being the paranoid electrician type, I let go of that sucker in a hurry! VOM showed ~20v. (Dunno whether AC or DC; I'm assuming AC.)

Reply to
David Nebenzahl
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True for Detroit Edison, as well.

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Reply to
Arny Krueger

In article , Don Pearce writes

Me too!, virtually every bit of wire string the electricity grid together in the UK is Three phase. Only in some remote places will you see overhead High voltage in Single phase, and that only is likely to serve a signal customer!..

Can't believe the USA is that different?. I know or hear that they have split centre tapped supplies for 115 and 240 volt domestic supplies...

Reply to
tony sayer

The electrician re-wiring my house 25 years ago told me ring-mains were originally developed on battleships. Less chance of localised damage taking out a load of equipment.

The main advantage in domestic installations was that smaller cable could be installed for a given power load. With the demise of electric fires and 15 amp outlets, spur wiring was permissible and becoming more common.

Earthing seems to be almost as much a black art as is car electrics :-) I don't pretend to understand it, but apparently changes in the UK system have introduced stringent new requirements for cross-bonding all kinds of things that weren't necessary before. Anyone know more about this?

Reply to
Laurence Payne

Different resistance/impendence between different parts of the equipment and "ground". Whatever that is.

Reply to
Laurence Payne

On Tue, 18 Apr 2006 23:07:30 +0100, Palindr?me Gave us:

Excellent response!

The optical also reduces the number of elements in the run to one (TOS), or two in the case of speaker feeds.

Heck, there are even speakers that have their amps integrated into them that take optical feeds. In fact, that is the best manner to reproduce sound is an amp right next to the acoustical transducer. One doesn't need crossover networks in one's speaker if each driver has its own amplifier. Just massage the corners a bit.

Reply to
Roy L. Fuchs

On Wed, 19 Apr 2006 10:34:58 +0100, tony sayer Gave us:

Here, the pole transformer secondary (service side) is a center tapped 240 volt output (there are buck and boost taps on some).

Homes here get the full 240 with the centertap (neutral), and within the home, it is routed about as a single side hot-to-centertap, 120 volt run. The oven, furnace, dryer, inline hot water, etc (high power devices) typically gets the full center tapped 240 feed. The center tap is ground at the service panel with a ground rod, and all fault returns (third wire) also come back to this grounded terminal bus.

All the 240 volt branches get dual breakers and all the 120 volt runs get a breaker installed on that side of the service panel it will be drawing from.

That makes any single run in the house 120 volts from ground (or neutral).

Anyway, the pole transformer feeds several (4?) houses, then another transformer is used for the next quad of houses The HV feed at the top of the power distribution poles in Ohio was like 11kV IIRC (not sure), and I don't know if it was 3 phase or not. I do know that our

3 phase is not like California's. They are Delta. I think Ohio is Wye.

They may balance their consumption by sending a different phase to an entire neighborhood, and another to the next neighborhood down the way. Seems costly to do it house by house by house as you say is the case where you are.

Reply to
Roy L. Fuchs

On Wed, 19 Apr 2006 10:33:59 -0400, "mc" Gave us:

If it were two separate circuits, would it not make sense to think that there would be a small chaotic potential to be read across them?

Reply to
Roy L. Fuchs

On Wed, 19 Apr 2006 17:02:04 +0100, Andy Gave us:

Uh oh... all bets are off... ;-]

Till we see that new photo posted.

Reply to
Roy L. Fuchs

On Wed, 19 Apr 2006 12:12:25 -0400, snipped-for-privacy@aol.com Gave us:

Reminds me of an ESD fiasco I had at one place I fixed up while I worked there.

We drove a ground rod in the shop, into the earth at a little breakout point in the slab of our floor.

The potential between the grounded benches and the AC system grounded SMD reflow bench was 90 volts. Enough that I could feel the tinge in my arms if I rested them on the mat for that bench. That shop was in sad shape.

Reply to
Roy L. Fuchs

On Wed, 19 Apr 2006 11:46:44 -0800, snipped-for-privacy@apaflo.com (Floyd L. Davidson) Gave us:

His eyes should begin to open right about here.

Reply to
Roy L. Fuchs

Essentially everything metallic that is a fixture within a house must be bonded to mains ground. This includes everything in the plumbing system - sinks, bathtub etc. The ground wires for the ring mains just follow along with the power wires and ground all the metal outlet and switch boxes,

d
Reply to
Don Pearce

tony sayer spake thus:

Yes, what's so strange about that? We get three wires coming into our houses: one neutral and two hots. The hots are each 120 (nominally) with respect to the neutral, with 240 between the hots.

Reply to
David Nebenzahl

I meant a diagram that *explained* what a ground loop is. Your diagram does nothing, and isn't even a electrical diagram, much less one of a ground loop circuit. Here is the electrical equivalent diagram for your "ground loop",

Desired Signal Source

o o | | | +-------+ | | Rload | | +-------+ | | | +-------> connection =======//=======

Reply to
Floyd L. Davidson

In article , David Nebenzahl writes

Thats not strange as such, just the general lack of 3 phase distribution.

Why do you still use 115-120 supplies what with the extra current demands, or is there still a perceived electric shock issue?.....

Reply to
tony sayer

In article , Roy L. Fuchs writes

Thanks for that enlightening post. It may well be that we don't have the centre tapped supply arrangement. In the local substation Y arranged, the centre is earth connected and referred to as the Neutral return and each phase is then carried on a three conductor cable with the wire armouring used as the neutral return and its also connected as the safety earth.

as strange as that may seem;).....

Reply to
tony sayer

Mine isn't even an electrical diagram? At least it had the load at the right end of the cable. You have put it at the same end as the source. This is just nonsense.

Why are you telling me this?

No more so than mine.

Common mode DC equalization? What has DC to do with any of this, and what do you mean by equalization.

Are you still insisting that in a ground loop there are two signal connections and one ground connection?

What do you mean by separate grounds? Separate from what? You have grounded the equipment at each end, and also connected them by the cable shield. This forms a ground loop and cures nothing.

No, the thread has effectively been killed by your diagrams that won't survive the threading process, and are hence not discussable in any meaningful way.

If you want to carry on believing that a ground loop needs two signal paths and one ground path, I am happy to leave you to it.

d
Reply to
Don Pearce

To be able to give a complete answer we would need to know the output impedance values for your stereo and TV.

The output impedance (resistance) will tend to combine with the cable capacitance to make an RC low-pass filter. This may or may not matter, but to estimate the effect we'd need to relevant values.

Slainte,

Jim

Reply to
Jim Lesurf

All true. It's called "legacy technology". Unlike Europe, the US missed out on the cleansing benefits of being the site of a world war.

Reply to
Arny Krueger

Most US factories that use substantial amounts of power use 3 phase. It's mostly just the residential areas and isolated light industrial areas that lack it.

Electric power use per capita in the US is closer to being uniform or decreasing, as opposed to there being extra current demands.

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"Total primary energy use per capita in the United States in 2000 was almost identical to that in 1973. Over the same 27-year period economic output (GDP) per capita increased 74 percent"

Since 2001 or so, there has been a major conversion of existing residential lighting to compact fluorescent bulbs which produce about 3 times as much light per watt.

Reply to
Arny Krueger

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