# 110 Volt supply



## Magic Electric

Hi All, just a general question about 110 volt supply. its been a while but can anyone explain to me how 110 volt supply is safer than 240 volts. im not sure how its safer. like 110 volt shavers in a bathroom are selv. does 110volt supply in an industry work in more or less the same way.
many thanks


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## electricista

Magic Electric said:


> Hi All, just a general question about 110 volt supply. its been a while but can anyone explain to me how 110 volt supply is safer than 240 volts. im not sure how its safer. like 110 volt shavers in a bathroom are selv. does 110volt supply in an industry work in more or less the same way.
> many thanks


Well more people in the US die from 120V then any other voltage but that is also because more people are subject to 120V. 

!20 volts is 120V whether in a residence or a factory.


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## cornishsparks

55v to earth


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## Ecopat

Found this, hope it helps to clear things up for you.


Sorry guys, that line about it' s the current not the voltage is just something people say. I am electronics engineer. Ohms law goes I=V/R in this case. Assuming the voltage is 110 the resistance of the human body is about 5000 ohms with wet skin, and can be lower than 5000, the current in this case is 22 milli-Amps .022 amps It takes about 10-20 micro-amps or .0000010 amps across the human heart to kill. Many more are killed by 110 because it is easier to contact. When you are running 110VAC you have a line and a safety ground and common or return ground. When you run 220 you have a 110 line and a second 110 line on the other side of ground. The lines are 110 +110 = 220 plus a safety ground. The biggest reason 220 is used in the U.S. is to push more wattage with smaller wire. If you contact both 110 wires across your body you have doubled the current flow 220/5000 or 44 milli-Amps. However most people get between one line and ground and thus the voltage is only 110 since the scheme is 110-GND-110. The safety RCD scheme goes 55-safety GND-55 and 55+55=110. It is the same scheme as 220 off the pole.

When the voltage rises or the resistance drops the current goes up. Most people getting over 1000 volts across or lengthwise through the body die. But even 20 or 30 volts can kill under the right conditions. 

Clive is also correct about the isolating transformer but, the safest scheme with a isolating transformer is to use a non center tapped transformer with neither side connected to earth. That way you contact either line alone with your feet in 3 feet of water without being shocked. This is why OSHA requires isolating transformers. However most still use the center ground in case the line should contact high voltage. This condition would cause the breaker of the HV line to trip.

Gary
*Source(s):*

http://brebru.com/electricalpower.html
http://www.allaboutcircuits.com/vol_2/ch...


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## electricalperson

cornishsparks said:


> 55v to earth


in us we have 120v to earth if we install an isolation transformer we get 60v to earth each wire

we ground the neutral at the pole and house and that makes it so we get 0 volts neutral to earth. if you have an ungrounded neutral you will get funny voltages especially off of a transformer


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## RePhase277

electricalperson said:


> in us we have 120v to earth if we install an isolation transformer we get 60v to earth each wire
> 
> we ground the neutral at the pole and house and that makes it so we get 0 volts neutral to earth. if you have an ungrounded neutral you will get funny voltages especially off of a transformer


Unless the isolation transformer is center tapped and that tap is grounded, then there is no way that you will get a real voltage reading from either leg. Then it wouldn't really be an isolation transformer anyway.


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