[Boatanchors] Storm Damage to Electronics

[Sheldon Daitch]

Bob,

I do recall one home in my small Georgia hometown where
someone had built a rather large home and they had to have
three phase for the air conditioning system.  But only the
largest homes have three phase stateside.

Not that it was important but he was a W4 two letter
original call.

GFCI at the panels has been the normal outside the US for
many years.  In the place we are living, the lighting circuits and
the receptacle circuits are divided, by function, and each function
has its own sub-main three-phase GFCI breaker.

I think the standard allows for a higher ground fault trip current
level for the lighting circuits, 300 mA, mind, while the receptacles
require 30 mA trips.

73
Sheldon







On 11/9/2011 5:21 PM, rbethman wrote:
> Sheldon,
>
> Yes, there is an entirely different methodology/mentality in Europe, 
> Asia, and Middle East.
>
> One exception that I know of would be Korea.  However, this is due to 
> the very close nature of their systems and our assistance since the 
> Korean War.
>
> The U.S. has its methodology/mentality in a different direction.  Long 
> haul distribution is mostly in Delta. Long haul distribution is also 
> 125KV on the low end, and 250KV or much more.  Once it hits the 
> substations, then they break it down to WYE for primarily residential, 
> and for the normal voltages used in homes.
>
> U.S. Generation is *almost* exclusively WYE.  There are few 
> exceptions.  They use relays to sense excess ground current.  This 
> normally indicates a transmission fault, or VERY large load imbalances.
>
> They use the three phase for the large commercial loads.
>
> We see the line voltages in the home around 125 to 127 line to 
> ground/neutral.  Most folks don't even realize that ground and neutral 
> are bonded to the frame of the service entrance panel.  This is the 
> ONLY place that it occurs.
>
> GFCI circuits are now required.  That is where the "safety" grounds 
> come into play.
>
> Bob - N0DGN
>
>