Wikipedia:Reference desk/Archives/Miscellaneous/2022 December 22

= December 22 =

Photo credits
Is there a specific license I must obtain to use photos found on Wikipedia pages? Is there a recommended attribution? GHorvitz (talk) 15:03, 22 December 2022 (UTC)
 * You'll probably get a better answer at the WP: Help desk. Clicking on any WP image will get the file information page having its attribution, usually  CC BY-SA 3.0.  Details:  Reusing content outside Wikimedia 136.56.52.157 (talk) 16:14, 22 December 2022 (UTC)
 * Better explanation: About The Licenses  136.56.52.157 (talk) 19:21, 22 December 2022 (UTC)
 * Thanks! Perfect. :-)) GHorvitz (talk) 19:36, 22 December 2022 (UTC)

Three Phase Power for Safety
In the Kennedy Space Center reference for their IMAX exhibit, it details the projector system and notes that it uses three phase power for safety. I've been asked what is safe about the meaning of "for safety" in this context. In researching, I cannot find any reason why three phase power is safer, particularly for a movie projector. Is there an obvious reason that would be too mundane to have references scattered about the internet? 97.82.165.112 (talk) 16:50, 22 December 2022 (UTC)
 * As our article says, “ As compared to a single-phase AC power supply that uses two conductors (phase and neutral), a three-phase supply with no neutral and the same phase-to-ground voltage and current capacity per phase can transmit three times as much power using just 1.5 times as many wires (i.e., three instead of two). Thus, the ratio of capacity to conductor material is doubled.[9] The ratio of capacity to conductor material increases to 3:1 with an ungrounded three-phase and center-grounded single-phase system (or 2.25:1 if both employ grounds of the same gauge as the conductors). This leads to higher efficiency, lower weight, and cleaner waveforms.” DOR (HK) (talk) 02:13, 23 December 2022 (UTC)
 * I share the OP's puzzlement. On seeing their query earlier, I went and read that article, but failed to find anything that obviously related to increased safety: "higher efficiency, lower weight, and cleaner waveforms" might well mean lower installation, operating and maintenance costs, and perhaps better performance, but none of that seems to me to have any implications of safety for the Center's visitors, and no obvious ones for the Center's employees. {The poster formerly known as 87.81.230.195} 51.194.245.235 (talk) 05:30, 23 December 2022 (UTC)
 * Is the reference a printed document? What is the precise statement? --Lambiam 06:50, 23 December 2022 (UTC)
 * A three-phase supply is actually more dangerous than a single-phase supply as the voltage across phases is higher and more likely to result in a fatal shock. Shantavira|feed me 09:45, 23 December 2022 (UTC)
 * Xenon arc lamp looks like less Ripple current might make it safer for the equipment, and would there be less leakage current in the power supply filtering in 3 phase? fiveby(zero) 18:37, 23 December 2022 (UTC)