B1 pre earth safety question (newbie) - diyAudio
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Old 15th June 2009, 09:22 PM   #1
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Default B1 pre earth safety question (newbie)

Sorry for the possibly stupid question showing the very limited knowledge I have. I tried to search the 1750+ long thread on the B1 to find an answer, but no luck.

I'm putting together a B1 from using the board purchased at passdiy. It will be a 2 boxes system with the power supply in one and the pre itself in the other. I plan to have the box containing the power supply grounded to earth.

My question is, do I need for safety to run a chassis ground connection from the second box to the one containing the power supply, or is OK to leave it like that?

Thanks for your help,
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Old 15th June 2009, 11:04 PM   #2
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The general answer is yes, you should arrange for an earth ground
connection for any component which might conceivably get connected
to the AC line.

There are switching supplies out there (wall wart types and such) which
are safety approved and which often don't provide an earth ground at
all. Presumably their output is safe not being earth grounded.

If you are building your own supply, you should hard ground it's
chassis to the Earth terminal of the AC power socket, provide minimal
value fusing on both AC lines (live and neutral), and also ground the
secondary supply ground which is also probably your chassis ground on
the chassis which is separate from the supply.

Often grounding the secondary supply ground results in ground loops,
and it is common practice to ground this through a diode bridge or
power thermistor in an effort to provide some signal isolation while
still having a path to ground. The bridge or thermistor should be
able to withstand without damage, those current which will be get
through the fuses.

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Old 16th June 2009, 04:30 PM   #3
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Join Date: Nov 2008
Thanks so much for taking the time to answer my question Nelson, very much appreciated.

I will do some search to implement the bridge or thermistor solution you suggested before trying to test the pre-amp in my system,

Best regards,
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