Re: Am I going to blow myself up with AC power and a surge protector?

M. Collins

On Sat, Sep 25, 2021 at 03:46 PM, ap@... wrote:

Finally there’s using three different AC -> DC adapters.  I’m a proponent of grounding all of those together so there are no floating voltages against their ground, because if there are, these tend to flow over other connections not intended to carry significant current, notably USB cables. 

  In general, it's not necessary to do more than connect your AC adapters into outlets which are closely coupled, as on a power strip. All AC adapters with two-prong plugs, and most with three prong plugs provide isolation between the DC output and the contacts in an AC outlet. If you use a power strip near the telescope and plug all of the adapters into it, you should have no problems at all. Even if you run an Ethernet cable back into your house, there's little risk of problems because the connections are transformer coupled on each end (meaning that there's no direct path for current to flow from the Ethernet cable to the electronics on either end). USB is a little different since it relies upon current flow at both ends of the cable, so you may not want to run that between your office and telescope, however connections between cameras, filter wheels, computers, etc., at the telescope should not present any issues.

  The recommendation to ensure that you have GFCI protection for any line voltage used outdoors is a good one. An inexpensive ground fault detector is a worthwhile tool for any homeowner. These provide a button that allows a small current to pass between line voltage and ground, which will trip a GFCI if there is one in the circuit. If you plug the tester into an outdoor outlet and the lights on the tester don't go off as soon as the test button is pressed, either the existing GFCI has failed or there wasn't one to begin with. That's not a good thing.

  In many houses, the GFCI protecting outdoor outlets is installed in one of the bathrooms. If you have a GFCI in a bathroom, you can plug a lamp into an outdoor outlet then press the test button the GFCI. If the lamp goes off, the outdoor circuit is properly protected.

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