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View Full Version here: : Earths ain't Earthed?


pjphilli
13-08-2017, 12:15 PM
I have just installed a new QHY9 camera and I noticed that they advise connecting the power after all other connections have been made and not to "hot plug" functions when they are powered up. I have always adopted this practice.

In refiguring my backyard astro setup my mind turned to the general subject of "earthing" and the possibility of "stray" earth currents. My setup involves approx 10 metres of 240vac cord to my gear. I have an earth leakage breaker at the power point and I have also installed an electromagnetic interference filter (rescued from and old PC) at the 240volt temination to minimise RF pickup as we are living in a sea of it. In view of the long distance that my house wiring may travel to find a "real" earth it is possible that the 240 volt earth supply to my astro gear is floating a bit above "earth".

The control PC is earthed by default and my camera and mount may be earthed via USB etc connections to the PC.
However, I notice that the 12 volt 5amp power supplies feeding my camera and mount are both "floating" with the negative DC connection not connected to the mains input earth.

My question: Is earthing really a problem and to what extent should we make sure that all the gear is earthed (eg mount and camera)?
Perhaps worries about "earth currents" are an urban myth?

I could not find a previous thread on this matter but please point me to one if it exists on this forum.

Peter