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Author Topic: Busted power strip....  (Read 7961 times)

Greg_Cameron

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Re: Busted power strip....
« Reply #10 on: November 08, 2013, 12:52:06 pm »

One topic to maybe add to this forum for discussion would be so-called "surge protector" power strips. My understanding is that with the cheapies, the MOVs don't last long and can start leaking current into the neutral and ground buses which can cause noise and other problems. I also recall years ago reading that you're not supposed to daisy chain surge strips off of each other or off of UPSs. I make it a point to never do that and if I need more outlets split off of a UPS or another surge strip, I use "power tap" labeled power strips which means they don't contain MOVs or other components.  Any input on that topic Mike?
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Mike Sokol

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Re: Busted power strip....
« Reply #11 on: November 08, 2013, 02:11:00 pm »

One topic to maybe add to this forum for discussion would be so-called "surge protector" power strips. My understanding is that with the cheapies, the MOVs don't last long and can start leaking current into the neutral and ground buses which can cause noise and other problems. I also recall years ago reading that you're not supposed to daisy chain surge strips off of each other or off of UPSs. I make it a point to never do that and if I need more outlets split off of a UPS or another surge strip, I use "power tap" labeled power strips which means they don't contain MOVs or other components.  Any input on that topic Mike?
I do know that standard MOV surge strips can leak up to 3 mA between hot and ground. So adding two MOV surge strips on a single GFCI circuit can easily cause it to nuisance trip at the 5mA threshold. Also, as you indicate, a MOV is a sacrificial element that will eventually "wear out" from absorbing multiple voltage spikes. The bad thing is that you really don't know if the MOV is still working or not. Some of the high-end surge protectors (not sure if they're MOV based) have an indicator light to tell you if the surge protector is still working. Not sure how they generate the signal for the indicator light, but that would be an interesting thing to know. I'll call a few of my EE buddies to see if any of them have a handle on it. I think that's a great idea for a topic.
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Greg_Cameron

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Re: Busted power strip....
« Reply #12 on: November 08, 2013, 04:21:45 pm »

Years ago, I had two racks at FOH, both with Furman "power conditioner" rack units. I had one rack's Furman plugged into the other. I had my Mac laptop sitting on the one Rack that was chained to the other. When I rested my hand on the metal rack edge and touched my laptop, I got a mild but noticeable tingle on my fingers. I reconfigured my power so that that both racks were plugged into the quad box stringer coming from my main distro rather than a daisy chain and the issue subsided. I suspect there were some leaking MOVs causing noticeable ground voltage differential between the quad box and racks. Daisy chaining Furmans probably exacerbated the issue. I never do it anymore.
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Re: Busted power strip....
« Reply #12 on: November 08, 2013, 04:21:45 pm »


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