[GreenKeys] Teletype Model 15 Pull Bar?

[Dave Horsfall]

On Fri, 31 Mar 2017, Larry Tighe wrote:

> Thanks for that information on voltage.  Can you tell me if one of the 
> two legs is at ground potential or is the voltage "floating" above 
> ground?

Ahh...  The answer is Yes and No :-)

Australia, in common with most of Europe, uses "MEN" i.e. Multiple Earth 
Neutral.  Each outlet is 3-pin (polarised of course), with Active, 
Neutral, and Earth.  The difference is that Earth is bonded to a copper 
stake outside the premises, whereas Neutral is bonded back at the local 
distribution point.  It's not unusual (to quote Tom Jones) to see several 
volts 'twixt Neutral and Earth, due to earth resistance and leakage.

This is where it gets complicated, such as appliance leakage and having no 
residual current devices (which you won't find in old premises), with 
Earth floating up to 120v and you touch a metal sink...  You will never 
ever see me touching something electrical and something grounded at the 
same time; how secure is *your* ground bond?  Trouble is, copper pipes are 
beginning to be replaced with plastic, because the bean-counters are now 
running the show.

AS/3000 pretty much says it all.  (Yes, my Daddy was an electrician.*)

[*]

Yes, I know lots of sparkie jokes, such as:

What's black and crisp, and hangs from the ceiling?  A dead electrician.

Remember: there are old electricians, and there are bold electricians...

-- 
Dave Horsfall DTM (VK2KFU)  "Those who don't understand security will suffer."