On Sun, 10 Apr 2022 14:23:56 -0700 (PDT), Phil Allison
<pallison49@gmail.com> wrote:

>Joe Gwinn wrote:
>================
> >
>> >** There is no huge problem with players standing a few metres away from any AC transformers in the vicinity.
>> > The mag field from an AC transformer is purely short range.
>> > The need for humbucking PUs arose from those who sit next to or even on top of their amps.
>>
>> Not so fast. A classic source of widespread hum fields is wiring
>> errors or failures in the power wiring of the venue.
>
>** So you say.
>
>
>> In the US, ring busses are not allowed,
>
>** Nor here - only in the UK AFAIK.
>
>Such a buss feed a loop of AC outlets ( active and neutral) from both ends.

Yes, unless there is a break somewhere. With luck, all the outlets
will still work just fine, and nobody will be any the wiser. But the
current will travel in a room-size or building-size loop, generating a
pervasive magnetic field.

>> > As it happens, nearly all humbucking PUs have full ES shielding too, so are dead quiet.
>
>> Yes, that's true these days.
>
>** Been true since the 1950s.

I did run into lots of exceptions.

>All the popular humbuckers ( Gibson, Fender and Asian clones) are metal cased.

Yes. I don't know when the transition happened, but it had to be
gradual.

Joe Gwinn

Joe Gwinn <joegwinn@comcast.net> wrote in
news:qnf65htct3oq80qj2klema4nkemv962puo@4ax.com:

> In the US, ring busses are not allowed, so out and back currents
> are close to one another, and their magnetic fields largely
> cancel. Unless someone reversed power neutral (white wire in the
> US) and safety ground (green wire). Which I have personally
> encountered.
>

I worked in a lab once where the PnP machine and the reflow oven
benches were 90V to Earth ground. No hard current capacity that I
could see, but still... They were clueless about ESD much less the
introduction of stray line voltages. And it made for a very unpleasant
tickle when one touched the wrong elements of the work area. I left
that job pretty quickly. I do not like to work for idiots.

Phil Allison <pallison49@gmail.com> wrote in
news:ba4a605d-3844-4304-9f09-609fce1679e3n@googlegroups.com:

> Joe Gwinn wrote:
> ================
> >
>> >** There is no huge problem with players standing a few metres
>> >away from any AC transformers in the vicinity.
>> > The mag field from an AC transformer is purely short range.
>> > The need for humbucking PUs arose from those who sit next to or
>> > even on top of their amps.
>>
>> Not so fast. A classic source of widespread hum fields is wiring
>> errors or failures in the power wiring of the venue.
>
> ** So you say.
>
>
>> In the US, ring busses are not allowed,
>
> ** Nor here - only in the UK AFAIK.
>
> Such a buss feed a loop of AC outlets ( active and neutral) from
> both ends.
>
>> > As it happens, nearly all humbucking PUs have full ES shielding
>> > too, so are dead quiet.
>
>> Yes, that's true these days.
>
> ** Been true since the 1950s.
>
> All the popular humbuckers ( Gibson, Fender and Asian clones) are
> metal cased.
>

Grounded metal case, as opposed to an isolated metal case. Can't
leave that out.

mandag den 11. april 2022 kl. 01.27.40 UTC+2 skrev DecadentLinux...@decadence.org:
> Joe Gwinn <joeg...@comcast.net> wrote in
> news:qnf65htct3oq80qj2...@4ax.com:
> > In the US, ring busses are not allowed, so out and back currents
> > are close to one another, and their magnetic fields largely
> > cancel. Unless someone reversed power neutral (white wire in the
> > US) and safety ground (green wire). Which I have personally
> > encountered.
> >
> I worked in a lab once where the PnP machine and the reflow oven
> benches were 90V to Earth ground. No hard current capacity that I
> could see, but still... They were clueless about ESD much less the
> introduction of stray line voltages. And it made for a very unpleasant
> tickle when one touched the wrong elements of the work area. I left
> that job pretty quickly. I do not like to work for idiots.

likely a missing earth so caps the EMC filters form a capacitive divider
to what should been earth

Joe Gwinn wrote:
================
> >
> >> >** There is no huge problem with players standing a few metres away from any AC transformers in the vicinity.
> >> > The mag field from an AC transformer is purely short range.
> >> > The need for humbucking PUs arose from those who sit next to or even on top of their amps.
> >>
> >> Not so fast. A classic source of widespread hum fields is wiring
> >> errors or failures in the power wiring of the venue.
> >
> >** So you say.
> >
> >
> >> In the US, ring busses are not allowed,
> >
> >** Nor here - only in the UK AFAIK.
> >
> >Such a buss feed a loop of AC outlets ( active and neutral) from both ends.
>
> Yes, unless there is a break somewhere. With luck, all the outlets
> will still work just fine, and nobody will be any the wiser. But the
> current will travel in a room-size or building-size loop, generating a
> pervasive magnetic field.

** A rare event, only in the UK and the field is weak compared to typical transformers.
>
> >** Been true since the 1950s.
>
> I did run into lots of exceptions.

** Seems you are accident prone.

> >All the popular humbuckers ( Gibson, Fender and Asian clones) are metal cased.

> Yes. I don't know when the transition happened...

** What "transition" was that ???

...... Phil