Can an HDMI cable be hot-plugged?

HDMI (High Definition Multimedia Interface) transmits uncompressed high-definition video and multi-channel audio data at high quality, and it does so without requiring any digital-to-analog or analog-to-digital conversion before the signal is sent. This ensures the highest-quality audio/video signal transmission, which is why it is so widely used.

Yes, HDMI supports hot-plugging. One of the pins in the HDMI standard is actually named "Hotplug": once the HDMI cable is plugged into a device (such as a TV), the Hotplug pin is pulled high, and the transmitting device (such as a laptop) only starts sending HDMI signals after it detects this high level. So in theory, HDMI cables do support hot-plugging.

However, this does not mean hot-plugging is 100% safe. HDMI carries very high-speed digital signals, and to enable fast transmission, the anti-static protection circuits used in the send/receive chips are generally only rated to withstand 5–8 kV of static voltage. Although this meets the standard, in real life — if the environment is dry and conditions that generate static are present — static voltages of over 10,000 V (10 kV) are common. Therefore, hot-plugging can potentially produce electrical sparks that destroy the chips.

For this reason, well-designed source and display devices typically give up some capacitance margin to add ESD protection circuits. But some devices omit ESD protection to save costs, and in those cases, plugging in a static-charged HDMI cable can burn out the chip.

All in all, to ensure absolute device safety, hot-plugging an HDMI cable is not recommended. That said, if it only happens occasionally, it's generally fine.