- Jul 1, 2019
- Ventura, CA
I don't want to enter the telescoping versus star grounding strategy argument, but I do take issue with the use of anti-parallel connected diodes to protect against fault currents. It is a fact that, when a ground-fault occurs, the short-circuit current is limited primarily by the resistance in premises wiring. According to studies done by UL (Underwriter's Laboratories) in the US, fault current can range from 150 A to over 1,000 A until the circuit breaker opens - and this can take from 50 ms to over 2.5 seconds. This will quickly turn a 6 A or 8 A rectifier into silicon vapor and an open circuit! There is a product called "Hum-X" that does exactly this. It's been on the market for at least 15 years. Every time I see them at a trade show, I stop and ask where their UL or other agency approvals are. And, for 15 years, the answer has been "Oh, we're working on that." And I tell them not to hold their breath. I would never use this product or use it as a "cure" for grounding issues ... it's a deadly accident waiting to happen. But then audiofools will buy almost anything if the advertising contains enough buzz-words. Many have been told that only one piece of gear in your system has to actually be connected to safety ground because the rest of the system connects to it through signal cables. Can you imagine passing 100 A through the shield of an ordinary RCA cable? Have a fire extinguisher ready!