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I found this site on the Internet saying something to that effect:

Warning!!.....Never connect and disconnect HDMI cables and equipment while your devices are powered on (hot plugging cables). The hdmi cables carries a low DC voltage while connected. You will damage your equipment and the HDMI Distribution equipment while hot-plugging cables which will not be replaced under the 1 year manufacturers warranty. Only use the Switched Mode Power supply supplied with the HDMI Equipment since replacing the power adapter might damage your equipment if incorrect voltage is supplied to the equipment.

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    This answer says that HDMI is designed to be hot pluggable. Of course, that doesn't mean that a poorly designed device can't be damaged.
    – Johnny
    Dec 17, 2013 at 20:32
  • I don't think this question meets the standards of notability. Something your friend said isn't notable.
    – Publius
    Dec 17, 2013 at 22:30
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    @Articuno if there's any doubt that a claim is notable (such as in this case) then a demonstration of notability is required. The requirement for a reference to a notable claim is also useful, in that referenced claims are often more specific, and thus more answerable.
    – 410 gone
    Dec 18, 2013 at 7:05
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    @ene we'll clarify meta after discussion, that said: harassing every questioner who doesn't bring an example about notability is clearly not what was ever intended. The burden of verifying notability is up to the community. Before asking for notability samples, let's do a quick search.
    – Sklivvz
    Dec 18, 2013 at 9:18
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    @Avi no, the burden of proof is on us to google a claim before asking for notability...
    – Sklivvz
    Dec 18, 2013 at 10:37

1 Answer 1

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The Hot-Plug-Detection feature is part of the HDMI protocol. All data-lines are quiet until a hotplug-event is detected via the physical pin 19. A handshake then negotiates a real connection:

The HPD (Hot-Plug-Detect) feature is a communication mechanism between a source and a sink device that makes the source device aware that it has been connected/disconnected to/from the sink device. When an HDMI cable is inserted between the two devices, the resulting hot-plug detection instantiates a start-up communication sequence.

So, unless we're talking about massive static discharge - which should be prevented by opto-isolation if we're talking about a proper implementation - it is safe, even safer than USB which applies 5 V of Vcc right away without any prior negotiation.

Source: http://www.ni.com/white-paper/12680/en/

Edit: Regarding the physical USB connectors I should point out that the data- and Vcc-/mass connectors are not of the same length. If you plug it in, mass and power is applied before the data lines are physically attached. This works good enough for most applications.

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  • Thanks. So it never happens in practice? You don't statistically increase any risk of damage to the HDMI port at all, for any kind and any quality of HDMI cable, by hot-plugging your HDMI cable vs. turning one of the devices off, and then plugging it?
    – sashoalm
    Dec 18, 2013 at 7:33
  • No, I wouldn't claim that it never happens. I don't have any statistical data for this, just the words of your friend radio technician. But I can imagine that regular failure rates apply; after market introduction you see a higher failure rate ("infant mortality"), then over the regular lifetime an even distribution of failures and at the end of life a higher failure rate due to wear out. Also note that HDMI is now for about 10 years of the market so you will notice 1st and 2nd generation products to fail a lot by now. Anecdotal evidence could be interpreted as"fails too often".
    – Alexander Janssen
    Dec 18, 2013 at 7:53
  • I have the impression it is rare, still a few people claim that it destroyed their video card. Do you think it is possible to send the card back for warranty in these cases?
    – inf3rno
    May 1, 2020 at 9:24

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