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Can someone tell me if there is a maximum recommended length for a PC cord, whether officially or otherwise? I've seen some very long ones (30 feet!) and as I have some electrical engineering training I'm very suspicious of these. I know it's basically a connector for an electronic switch that sees very little power across it, but still, for safety and reliability I would like to know for sure.

I believe PC cords are standardized in ISO 519:1992, but I really don't want to pay to read it and maybe answer my question...

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    \$\begingroup\$ For what it's worth, 30 ft. PC sync cords work just fine, assuming the cord is in proper shape. \$\endgroup\$
    – Michael C
    Commented Oct 1, 2020 at 18:19
  • \$\begingroup\$ You are overthinking this. What's suspicious about long cords? What's the length of the entire circuit that you close when you turn on the ligths in a room? There are vacuum cleaners with 30ft cords... \$\endgroup\$
    – null
    Commented Oct 1, 2020 at 20:28
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    \$\begingroup\$ A PC sync cord simply allows the camera to complete the circuit when the shutter opens. There is no other communication across the cord -- so signal degradation isn't an issue. The only thing that could be an issue is resistance. But some flashes and cameras can allow for surprisingly high voltage (also note that trigger voltage across a sync cord is not necessarily the same as it would be for a shoe-mounted flash ... where lower voltages are often used.) \$\endgroup\$ Commented Oct 3, 2020 at 23:21
  • \$\begingroup\$ @null I would hope my home isn't wired with the same gauge used for PC cords! There are plenty of electrical differences between each scenario you offered and moderately high voltage DC switching. I knew I was probably overthinking things, but it was something I couldn't find an answer for. Keep in mind, the specific question I had was in regards to standards, regardless of any disaster scenario I might come up with. \$\endgroup\$
    – RICK
    Commented Oct 16, 2020 at 22:59
  • \$\begingroup\$ @TimCampbell I know signal degradation isn't an issue. I do use some older flashes and cameras, and I know the voltages are safe for my gear, I just wanted to find out if there was some official number for cable length. Thanks for the info! \$\endgroup\$
    – RICK
    Commented Oct 16, 2020 at 23:04

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PC sync tends to be rather low-current. The initial electromechanical contacts switched about 200V of trigger voltage without significant sparking. More modern flashes and cameras don't transfer actually significant currents but only flag voltages. There may be reflection doubling the voltage at a long essentially open end (compared to the line impedance) but generally devices tend to be comparatively tolerant of that kind of low-current bounce. I consider it unlikely that you'll cause any problems when the wires are aligned (coaxial or twisted pair) and the length is in a sensible relation to the distance where a flash is still useful (namely not in excess of a few hundred meters).

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