Hi Bryon,
Question for Jim:
Although the additional ground rod may very well not be helpful with respect to minimizing noise, I'm wondering how it would represent a safety risk in this particular application.
There are two reasons I can think of why code prohibits multiple ground rods that are not connected together.
One is that if it is used to ground the safety ground of an electrically powered device, fault current may not cause the circuit breaker to trip. That is explained on page 8 of this Bill Whitlock paper.
The other reason I can envision, which is also mentioned in the paper, is that if lightning hits the outdoor electrical wires and is conducted to ground through the main grounding rod, thousands of volts may briefly appear between the two grounding rods, potentially damaging anything for which a connection path to both of them exists.
Neither of those scenarios seems applicable to what Bryon was doing with the second ground rod, assuming that the means of insulation between the Reclocker and the Sonos and their grounded enclosures is sufficient to withstand the voltage that would appear across it during the lightning strike scenario. Perhaps that isn't a good assumption, though. Can you explain further? Thanks.
Best regards,
-- Al
As for why (3) sounded worse than (1) and (2) ... maybe grounding the enclosures to the G68 made the enclosures act like antennas collecting RFI, and that RFI was then transmitted into the G68?That would certainly seem like a possibility. In particular, perhaps noise originating from the enclosed devices is finding its way from the connection to the G68 chassis to the ground/signal return of the digital input to the G68. A noisy ground at that circuit point would certainly contribute to jitter, especially if the connection is unbalanced S/PDIF rather than balanced AES/EBU.
Question for Jim:
Although the additional ground rod may very well not be helpful with respect to minimizing noise, I'm wondering how it would represent a safety risk in this particular application.
There are two reasons I can think of why code prohibits multiple ground rods that are not connected together.
One is that if it is used to ground the safety ground of an electrically powered device, fault current may not cause the circuit breaker to trip. That is explained on page 8 of this Bill Whitlock paper.
The other reason I can envision, which is also mentioned in the paper, is that if lightning hits the outdoor electrical wires and is conducted to ground through the main grounding rod, thousands of volts may briefly appear between the two grounding rods, potentially damaging anything for which a connection path to both of them exists.
Neither of those scenarios seems applicable to what Bryon was doing with the second ground rod, assuming that the means of insulation between the Reclocker and the Sonos and their grounded enclosures is sufficient to withstand the voltage that would appear across it during the lightning strike scenario. Perhaps that isn't a good assumption, though. Can you explain further? Thanks.
Best regards,
-- Al