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According to my safety notes a lethal voltage is 120vdc or 50vac why is there such a big differential between the two?
Wiki User
∙ 13y ago
Firstly, history says that AC power is more dangerous. Thomas Edison was a huge advocate for direct current because it was safer to transport, to demonstrate this fact he electrocuted an elephant on Coney Island in 1903 using AC current (http://www.wired.com/science/discoveries/news/2008/01/dayintech_0104). As for the danger, and I may be wrong about this, but as the current travels through ones body the current spikes, then falls to as it sucums to the resistors. DC power spikes then remains lower, but AC because it is constantly switching spikes many times.
First, I think you have it backwards; AC (Alternating Current) is considered less dangerous than DC (Direct Current) in that, because it alternates, it may allow the victim to release hold of the source of the charge (20-30mA is enough charge to induce rigid paralysis near the site of the charge).
Note too that lethal electrical charge is more often a result of higher amperage than voltage. Static electricty, for example (the stinging zap you get from doorknobs on dry days) is very high voltage, but very low amperage.
Cjonb 17:02, 3 Jun 2008 (UTC)
Also your heart works via a small electrical pulse at around 75 pulses per minute. AC Volts across your heart will make your heart try to adapt the AC frequency which is like 3000 pulses per minute (50Hz). This is called fibrillation and is what makes AC Voltage so dangerous.
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∙ 13y ago
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What size wire is needed for 120VDC 1275 Amps?
For that current you would need five 0000 (4/0) wires in parallel for each side of the circuit, and they would heat to 90 degrees C if used for any length of time according to the NEC tables. Those wires have a diameter of 0.46 inch exactly. There are better ways of transmitting 153 kW if there is a higher voltage available.
What should be the current rating of a 120VDC 0.4A temperature switch at 24 V DC?
0.4A. The power dissipated in the switch and therefore how hot it gets depends on the current and the resistance.
How many DC amps are in an AC amp?
Watts in AC are the same as watts in DC. A watt is a unit of energy transfer, in units of joules per second. You calculate watts by multiplying volts (joules per coulomb) by amperes (coulombs per second). While watts are still watts, AC or DC, the calculation becomes more complex in AC for multiple reasons. Current is often not in phase with voltage due to capacitive or inductive reactance. This leads to additional terminology such as vars (volt-amps-reactive) and power factor (ratio of true vs apparent power). Current is often not continuous over the entire AC cycle, making the voltage or current (and thus the power) cycle non-sinusoidal. (In a power supply, for instance, current flows only when the input AC voltage is above the rectifier's forward breakdown voltage, and this only occurs as a pulse in the cycle when the filter capacitor needs to be recharged.)
