Hi Jim,
See my answers below:
In a message dated 3/19/2010 9:02:30 P.M. Eastern Daylight Time,
jim@audiosystemsgroup.com writes:
On Fri, 19 Mar 2010 19:31:11 EDT, HansLG@aol.com wrote:
>
>Hi Jim,
>
>I still don't get it (maybe because I am dumb). At my service entrance
is
>a protector that connects has two MOVs, one from each leg to ground.
Ground
>in this case is the same as neutral
That's very good (assuming it's a good unit).
This ground is the 8' grounding pole just at the entrance.
>At the water pump is also a protector
>that has MOVs from the two legs (the pump is a 240 V pump) and ground.
What is that "ground?" EXACTLY where is it connected? Is there any
control wiring
running from the water pump to anything else? How much inductance is in
the green
wire between there and the service entrance ground? These additional MOVs
have the
potential to cause a destructive failure. It is SAFE to have an MOV from
Line to
Line at that point.
The line comes from the pump relay. There are no other wiring here. The
green ground is approximately 30' from the service entrance. The green ground
is also connected to a uninsolated wire that goes down to the pump,
(something I questioned at the time of installation). The pump is an immersed
pump 50' down in the well.
>In the
> shack I have a protector that connects MOVs from neutral AND the hot 120
V
>leg to ground. It also incorporate a protecting circuits for my phone,
it
>has two gas discharge tubes between the line and ground.
Same questions -- what is that "ground?" EXACTLY where is it connected?
Is there
any control wiring running from the shack to anything else? How much
inductance is
in the green wire between there and the service entrance ground? These
additional
MOVs have the potential to cause a destructive failure. It is SAFE to have
an MOV
from Line to Neutral at that point.
The ground here is the green ground + a wire shield surrounding the shack.
(The shack is on the top, 4th, floor of my house. I didn't find the green
ground to be of any value for RF and added a large shield around the
shack.) The only "control wire" is the telephone line that is protected but
gas
discharge tubes, connected to the green ground.
>
>Should I disconnect al MOVs that are connected to ground ??? As I wrote
to
>you earlier, my house has had two registered lightning hits (and possible
a
> couple of more we don't know about) and everything survived.
>
>Can anyone describe the failure mode that makes the MOV from the hot leg
to
>ground bad?
I've done that several times in earlier posts. See also pages 29 and 30 of
_http://audiosystemsgroup.com/SurgeXPowerGround.pdf_
(http://audiosystemsgroup.com/SurgeXPowerGround.pdf)
I'll be happy to check that when I am at a better internet connection.
Thanks and 73 de,
Hans-N2JFS
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