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Old 04-24-2008, 09:41 PM
jackelope jackelope is offline
Join Date: Sep 2001
Location: Memphis
Posts: 5,892
Plugging into "power strip" vs. directly into wall is a problem?

About two weeks ago, the DVR function on my cable box (which I'd only had for a month or so) went out. When I'd try to go to the DVR menu, it would display a message on screen: "Unrecoverable Write Error." So I took it to the cable company, and they replaced it.

Then, about a week later, the new box did the exact same thing. "Unrecoverable Write Error." As before, I could still watch cable TV fine, but was unable to record anything. Couldn't pause, couldn't back up. I had to sit through commercials, people. It was horrible.

So I took it to the cable company, and they again replaced it. I mentioned that this was the second time in just a few weeks this had happened, and the lady asked if I had the box plugged into a power strip, or directly into the wall. I told her it was plugged into a power strip, one of those surge-protector things.

She said I need to plug it directly into the wall, because "it gets less juice" when it's plugged into a surge protector. I cheerfully agreed, thinking all along, "This sounds like hogwash."

So I went home and called my father, an electrical engineer, and asked him about it. He said a lot of technical stuff that I pretended to understand, the upshot being that no, the infinitesimal difference in current or power or something is almost certainly not the culprit here. We both agreed, for one thing, that "Unrecoverable Write Error" doesn't sound like a power-source problem; it sounds like a hard drive crash.

On the other hand, he pointed out that this lady works for the cable company, and almost certainly knows more about cable boxes than either of us. So he recommended I do as she instructed, just in case, which seems like good advice and that's what I'm going to do.

But what's the deal here? Surely, if the difference in power between a direct wall-plug and a power strip were large enough to fry cable boxes, this would be pretty common knowledge and it would be causing problems with other sensitive equipment all the time, right? Or is there some special property of DVR that makes it hyper-sensitive to minor variations in voltage?

What, in short, is the Straight Dope on this?
Old 04-24-2008, 09:51 PM
Q.E.D. Q.E.D. is offline
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Join Date: Jan 2003
Location: Richmond, VA
Posts: 22,536
No, for all intents and purposes, there is zero difference in power quality when plugging a device into an outlet strip versus a power strip. Most cheap power strips do have some rudimentary surge suppression in the form of a couple of MOVs across the lines, but this has no effect at nominal line voltage. There is a very, very slight voltage drop due to the extra six feet or so of 16 AGW wire between the wall and the device, but I couldn't measure it even with my Fluke DMM.

Short version: Cable co. lady is full of shit.

Last edited by Q.E.D.; 04-24-2008 at 09:54 PM.
Old 04-24-2008, 09:52 PM
mks57 mks57 is offline
Join Date: Dec 2003
Location: Seabrook, Maryland
Posts: 3,045
The difference between the wall outlet and the power strip is negligible. The power strip is likely to have line filters and overvoltage protection, which is a good thing.
Old 04-24-2008, 10:01 PM
DadWagonDriver DadWagonDriver is offline
Join Date: Jul 2002
Location: Back in the Mitten
Posts: 2,031
She probably was a bit misinformed. What she probably meant to ask was whether the coax was plugged into the power strip. The grounded cable input and output jacks on expensive power strips aren't shielded very well, and can lead to a few problems with the signal.
Old 04-24-2008, 10:05 PM
ZenBeam ZenBeam is offline
Join Date: Oct 1999
Location: I'm right here!
Posts: 8,858
I'm trying to think of why plugging it into a power strip could possibly be a problem. The most likely explanation I can think of is that some people turn off their power strips, and that can lead to a corrupted hard drive, like it can (could?) on a computer.

If you do turn the powerstrip off (or you wife does, or your kids do,or the dog...), stop.
Old 04-24-2008, 10:12 PM
jackelope jackelope is offline
Join Date: Sep 2001
Location: Memphis
Posts: 5,892
Thanks, all. This confirms what I suspected.

I'm going to plug it into the wall anyway, though, because if this one dies too and they give me a hard time about replacing it, I want to be able to truthfully say I did everything they told me to do. (Why yes, I am a lawyer.)

ZenBeam: I live alone, and the power strip is behind a big sideboard-type piece of furniture. No worries there.
Old 04-24-2008, 10:24 PM
Rick Rick is offline
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Join Date: Aug 1999
Posts: 16,451
I'm going to take a contrary view here.
If we are discussing a cheap power strip here, it is possible that through age, or overheating, or metal fatigue that one or more of the outlets might not grab the prongs of the plug tightly. This poor connection could cause a measurable voltage drop due to increased resistance.


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