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Why is there a voltage on my HDMI and coaxial cables?

156 pointsby jasonhanselabout 2 years ago

9 comments

nlyabout 2 years ago
I moved in to a newly renovated Victorian house here in England in December, which we bought from a property developer.<p>It was completely rewired, with everything signed off and certified by a qualified electrician, as per legal requirements.<p>Most properties in the UK have common earth&#x2F;ground and neutral wiring (they&#x27;re the same wire, the &quot;earth&quot; just bypasses your main board... there&#x27;s no earth spike).<p>Anyway, I bought a socket tester after noticing an outlet or two didn&#x27;t work. Went around and tested the whole house... half of the 30 electrical outlets in the house were defective, and at least 4 were wired incorrectly such that they were live on the neutral pin (which means they&#x27;re live when the switch is off). Some had earthing issues. Fortunately the RCBO&#x27;s work as advertised.<p>Don&#x27;t risk your life with this stuff, test it all yourself. A tester will cost you $10
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zenexerabout 2 years ago
&gt; I even checked my electricity &#x27;pen&#x27; reader on an HDMI at work to see if it was the reader. It&#x27;s not the pen. It&#x27;s my wires.<p>Ah… there it is. Stop using those; use an actual multimeter.<p>See, the problem with measuring voltage is that you really need two points of reference: you’re really measuring the voltage potential between two separate points.<p>When you say your HDMI is live, what does that mean? Relative to what? Are you talking about the grounded shielding, or one of other conductors?<p>This individual is waving around a no-contact A&#x2F;C voltage detector. These can be useful indicators in the right hands, but they’re just estimation devices. They’re prone to false positives and negatives.<p>If you wave one near an HDMI or coax cable, there’s a good chance it’s going to beep and turn red.<p>That being said, if you see your lights getting brighter on the regular (rather than dimmer), your neutral is probably going bad, and that can be quite dangerous. Call your electric company and&#x2F;or an electrician if you see that. It’s not going to stop your coax and HDMI from showing as live when you wave a death stick near it, though; they <i>are</i> live, at least from the perspective of a no-contact voltage tester.
londons_exploreabout 2 years ago
This sort of problem is a big moneymaker for electricians.<p>They look at it and say &quot;yeah, it&#x27;s fucked. You need a full rewire, $20k&quot;.<p>When the reality is that with a bit of measurement and testing you can find the missing or broken neutral or incorrect grounding, and fix it for a couple of hours work.<p>Nearly all electrical fires are caused by newly modified electricals anyway, so &#x27;just rewire it all&#x27; is probably making your property less safe rather than more safe, at least in the short term.
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hedoraabout 2 years ago
Would this explain all apple devices shocking me while charging?<p>(But to varying degrees, depending on the day, and not if I use a three prong plug for the USB power source.)
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junonabout 2 years ago
Fascinating, I never knew this is how it worked. I feel like I&#x27;ve run into this before at friends or family&#x27;s houses and shrugged it off as bad house wiring or the like.
js2about 2 years ago
Edit: nope. See reply.<p>Klein Tools RT210 Outlet Tester, $13, would&#x27;ve detected this in a jiffy.<p><a href="https:&#x2F;&#x2F;www.kleintools.com&#x2F;catalog&#x2F;electrical-testers&#x2F;gfci-outlet-tester" rel="nofollow">https:&#x2F;&#x2F;www.kleintools.com&#x2F;catalog&#x2F;electrical-testers&#x2F;gfci-o...</a><p>(If I ever have more money than I know what to do with, one of the things I&#x27;ll do with it is buy Klein&#x27;s entire catalog of tools. Just because.)
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madmodabout 2 years ago
I now know why I got shocked by the ground at my grandparents house
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rysertioabout 2 years ago
I have a similar issue with my VGA cables and I&#x27;m yet too find a solution.
sebazzzabout 2 years ago
Is this more prevalent in split-phase countries than three-phase or one-phase systems?