# 110v vs 120v ?



## dmxtothemax (Jun 15, 2010)

Is there still a 110v supply anywhere in the USA ?
Or is it all now 120v ?
Was there ever a 110v system.
Why some say 110v others say 120v

What gives:whistling2:


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## erics37 (May 7, 2009)

Pretty much all 120 nominal. 110 hearkens back to the days of yore. It's also easier to say (one less syllable).


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## FrunkSlammer (Aug 31, 2013)

Old people say 110/220, young people say 120/240. 

Only place with 110v is somewhere that's really sagging.


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## TOOL_5150 (Aug 27, 2007)

FrunkSlammer said:


> Old people say 110/220, young people say 120/240.



Thats very true


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## chewy (May 9, 2010)

Do you guys ever do 55v to ground 2 phase, giving 110 across phases?


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## Bad Electrician (May 20, 2014)

chewy said:


> Do you guys ever do 55v to ground 2 phase, giving 110 across phases?


For UV/OV relays in switchboards


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## 99cents (Aug 20, 2012)

General contractors call it 110/220.


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## T&K (Jun 18, 2012)

99cents said:


> General contractors call it 110/220.


"I need a 220 wire run over here, you got any of that?"


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## 99cents (Aug 20, 2012)

T&K said:


> "I need a 220 wire run over here, you got any of that?"


Yeah, they think there are only two wire sizes - 110 and 220  .


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## Big John (May 23, 2010)

Every time I hear an electrician using those terms, I'm bummed out. Nobody who's spent years reading meters should say "110."


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## T&K (Jun 18, 2012)

Big John said:


> Every time I hear an electrician using those terms, I'm bummed out. Nobody who's spent years reading meters should say "110."


Problem is, many self proclaimed electricians couldn't use a meter correctly if they had to.


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## Going_Commando (Oct 1, 2011)

Big John said:


> Every time I hear an electrician using those terms, I'm bummed out. Nobody who's spent years reading meters should say "110."


My thoughts. Old electricians and GCs seem to be the major hold outs. Should say anyone that has used a DIGITAL meter should say 120/240. Those old Simpson analogs were good, but that needle and tiny writing aren't as "Eureka" instilling as a digital meter. 

What I have never understood is why it goes 110/220 ,110/208, 277/480 and 550v. That's how my grandfather has always talked about voltages; and it never made sense to me. Why wouldn't it be 110/191 and 254/ 440? For Pete's sake, be consistent!


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## Bad Electrician (May 20, 2014)

Big John said:


> Every time I hear an electrician using those terms, I'm bummed out. Nobody who's spent years reading meters should say "110."


I have always said 120/208, I see voltages that are across the spectrum from a low of 89/154 to 130/225 but average is 115/199 to 124/214. Her we have some 265/460 the transformers come in at 120/208 and no one changes the taps until we get called in for low voltage issues these secondary's are generally 116/201

ON 3-phase Wye systems


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## micromind (Aug 11, 2007)

chewy said:


> Do you guys ever do 55v to ground 2 phase, giving 110 across phases?


I haven't seen that one yet, but I've seen plenty of potential transformer voltages of 69/120 Wye derived from high voltage (over 35KV) systems. 

Also, 120 (or thereabouts) open ∆ grounded B is common for low and medium voltage potential transformers. PTs have voltage ratios, so you might get 120, 115 or some other odd voltage depending on the primary voltage.


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## Big John (May 23, 2010)

chewy said:


> Do you guys ever do 55v to ground 2 phase, giving 110 across phases?


 Legitimate 2Ø or split single-phase? Closest I've seen is split 120V 1Ø that was 60V to ground on each leg.


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## JRaef (Mar 23, 2009)

History lesson:

"110V" is a legacy resulting from systems in the earliest days of electrification using AC distribution systems developed by Tesla for Westinhghouse. They had to compete with Edison, who was promoting DC for his electric lights, and through a series of experiments, he had settled on 100VDC as a compromised between safety and lumen output. So to make people willing to use AC, Westinghouse decided on 110VAC as a standard. I've read somewhere that he may have started out with 100VAC, but changed it to 110 because it sounded "better" than 100, kind of like the volume knob that goes to 11.

In the early days, once people started jumping all over the concept of long distance distribution of AC, there were different system voltages at almost every provider, ranging everywhere from 100-135V. That presented a challenge for equipment providers, especially those using motors, because a motor designed for 100V is going to fry at 135V. So over time, equipment vendors organized to try to force standards of conformity (the beginnings of NEMA). At first they settled on 117V +-10% as a compromise because the +- range works from 100-130V. If you look on 1920s vintage motorized devices in antique stores, you will often see them listed as 117V.

In the 30s, the REA (Rural Electrification Act) was enacted with the purpose of extending electrical service to farms and small towns, partly as a way to increase productivity. Because the REA administration did not want their work crews to have to carry multiple different transformer designs around in their trucks, they forced a settlement on 120/240V as the "DISTRIBUTION" voltage, meaning what the utility delivers, with 115/230V as the "UTILIZATION" voltage, meaning what the end device is designed for, acknowledging that there will be some voltage drop by the time it gets to the device. Later, those values were adopted by ANSI as the official standards. Those are the official standards to this day.

But still, the utilities that actually GENERATED AND DISTRIBUTED the voltage were not actually forced to change existing systems, they just had to used those standards for NEW systems. So to this day there are still pockets of legacy voltage levels in different places, which adds to the confusion all around. I don't personally know of any "110/220V" systems here in California, probably because the REA got here late. But I have been told they still exist.

As to 3 phase, it is 120/208, because 208 divided by the sq. rt. of 3, which is the phase to neutral voltage of a Wye transformer, is 120. Same for 480/277. Along the same lines of the residential voltage levels, there are older legacy systems for industrial use that are 440V, 450V, 460V, 550V and 600V, but officially it is now 480V dist., 460V util.


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## retiredsparktech (Mar 8, 2011)

chewy said:


> Do you guys ever do 55v to ground 2 phase, giving 110 across phases?


You must be referring to the British power tool source.
They use a 230 volt primary, isolation transformer with a 110 volt, centered taped secondary, so each leg reads 55 volts to the grounded center tap.
I've read that arrangement is only used in large industrial or construction sites.
I've also read, that the British Isles, harmonized with the rest of the European continent at 230/400 volts.


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## Going_Commando (Oct 1, 2011)

JRaef said:


> History lesson:
> 
> "110V" is a legacy resulting from systems in the earliest days of electrification using AC distribution systems developed by Tesla for Westinhghouse. They had to compete with Edison, who was promoting DC for his electric lights, and through a series of experiments, he had settled on 100VDC as a compromised between safety and lumen output. So to make people willing to use AC, Westinghouse decided on 110VAC as a standard. I've read somewhere that he may have started out with 100VAC, but changed it to 110 because it sounded "better" than 100, kind of like the volume knob that goes to 11.
> 
> ...


Holy crap. Thanks for the info!


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## ShaneDugas (Apr 24, 2010)

JRaef said:


> History lesson: "110V" is a legacy resulting from systems in the earliest days of electrification using AC distribution systems developed by Tesla for Westinhghouse. They had to compete with Edison, who was promoting DC for his electric lights, and through a series of experiments, he had settled on 100VDC as a compromised between safety and lumen output. So to make people willing to use AC, Westinghouse decided on 110VAC as a standard. I've read somewhere that he may have started out with 100VAC, but changed it to 110 because it sounded "better" than 100, kind of like the volume knob that goes to 11. In the early days, once people started jumping all over the concept of long distance distribution of AC, there were different system voltages at almost every provider, ranging everywhere from 100-135V. That presented a challenge for equipment providers, especially those using motors, because a motor designed for 100V is going to fry at 135V. So over time, equipment vendors organized to try to force standards of conformity (the beginnings of NEMA). At first they settled on 117V +-10% as a compromise because the +- range works from 100-130V. If you look on 1920s vintage motorized devices in antique stores, you will often see them listed as 117V. In the 30s, the REA (Rural Electrification Act) was enacted with the purpose of extending electrical service to farms and small towns, partly as a way to increase productivity. Because the REA administration did not want their work crews to have to carry multiple different transformer designs around in their trucks, they forced a settlement on 120/240V as the "DISTRIBUTION" voltage, meaning what the utility delivers, with 115/230V as the "UTILIZATION" voltage, meaning what the end device is designed for, acknowledging that there will be some voltage drop by the time it gets to the device. Later, those values were adopted by ANSI as the official standards. Those are the official standards to this day. But still, the utilities that actually GENERATED AND DISTRIBUTED the voltage were not actually forced to change existing systems, they just had to used those standards for NEW systems. So to this day there are still pockets of legacy voltage levels in different places, which adds to the confusion all around. I don't personally know of any "110/220V" systems here in California, probably because the REA got here late. But I have been told they still exist. As to 3 phase, it is 120/208, because 208 divided by the sq. rt. of 3, which is the phase to neutral voltage of a Wye transformer, is 120. Same for 480/277. Along the same lines of the residential voltage levels, there are older legacy systems for industrial use that are 440V, 450V, 460V, 550V and 600V, but officially it is now 480V dist., 460V util.


Great info! I've often wondered the same thing. 
The more you know....
Thanks


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## Meadow (Jan 14, 2011)

chewy said:


> Do you guys ever do 55v to ground 2 phase, giving 110 across phases?


Yup, in special applications like balanced audio power. However outside of audio installations its exceptionally rare. Our NEC requires one leg of 120 volts be grounded. 

Do you guys ever use 115 to ground on both legs to give 230 volts or 133 volts 3 phase to give 230 volts between phases?


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## micromind (Aug 11, 2007)

133/230 is fairly common with drive isolation transformers, as is 265/460.


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## eddy current (Feb 28, 2009)

Don't forget us Canuks with our 347/600. :thumbup: Very common in commercial.


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## don_resqcapt19 (Jul 18, 2010)

micromind said:


> I haven't seen that one yet, but I've seen plenty of potential transformer voltages of 69/120 Wye derived from high voltage (over 35KV) systems.
> 
> Also, 120 (or thereabouts) open ∆ grounded B is common for low and medium voltage potential transformers. PTs have voltage ratios, so you might get 120, 115 or some other odd voltage depending on the primary voltage.


Take a look at Article 647. 120 line to line with a center tap ground connection. Very limited permitted uses under the rules of the NEC.


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## micromind (Aug 11, 2007)

don_resqcapt19 said:


> Take a look at Article 647. 120 line to line with a center tap ground connection. Very limited permitted uses under the rules of the NEC.


I've never seen a system that's 60 volts from each phase to ground. 

I was referring to a 120 volt 3ø open ∆ grounded B system typically used for potential voltage supplying relaying, metering, etc.


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## chewy (May 9, 2010)

meadow said:


> Yup, in special applications like balanced audio power. However outside of audio installations its exceptionally rare. Our NEC requires one leg of 120 volts be grounded.
> 
> Do you guys ever use 115 to ground on both legs to give 230 volts or 133 volts 3 phase to give 230 volts between phases?


Nah, we are always 230v on each line to earth and 400 across them. 

From what Ive heard the railways used big transformers in their yards and workshops to give 55v on each line to earth. They did this as a safety precaution and they imported American tools with your plugs on them so they didnt get stolen by the workers as you couldnt use them in the home workshop.


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## Meadow (Jan 14, 2011)

micromind said:


> 133/230 is fairly common with drive isolation transformers, as is 265/460.





chewy said:


> Nah, we are always 230v on each line to earth and 400 across them.
> 
> From what Ive heard the railways used big transformers in their yards and workshops to give 55v on each line to earth. They did this as a safety precaution and they imported American tools with your plugs on them so they didnt get stolen by the workers as you couldnt use them in the home workshop.


Ok your like the brits then :laughing::jester: Is it true New Zealand or Australia had 433Y/250 at one point but latter drop to 240 then 230? 

FWIW a lot of older power networks in Belgium are 230Y/133 volts, with only phase to phase connected loads. Talk about lucky, no open neutrals to worry about:thumbsup:


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## chewy (May 9, 2010)

meadow said:


> Ok your like the brits then :laughing::jester: Is it true New Zealand or Australia had 433Y/250 at one point but latter drop to 240 then 230?
> 
> FWIW a lot of older power networks in Belgium are 230Y/133 volts, with only phase to phase connected loads. Talk about lucky, no open neutrals to worry about:thumbsup:


I havent heard of that, the small town Reefton on the way over to the coast where grandma and granddads farm was, was the first in the southern hemisphere to get it in 1888, which was just streetlights run from a hydro electric dam feed from the inangahua river, no idea what the voltage was, probabally wasnt even a transformer and the streetlghts just dimmed and brightened as the turbine slowed and speed up.


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## LGLS (Nov 10, 2007)

JRaef said:


> History lesson:
> 
> In the 30s, the REA (Rural Electrification Act) was enacted with the purpose of extending electrical service to farms and small towns, partly as a way to increase productivity. Because the REA administration did not want their work crews to have to carry multiple different transformer designs around in their trucks, they forced a settlement on 120/240V as the "DISTRIBUTION" voltage, meaning what the utility delivers, with 115/230V as the "UTILIZATION" voltage, meaning what the end device is designed for, acknowledging that there will be some voltage drop by the time it gets to the device. Later, those values were adopted by ANSI as the official standards. Those are the official standards to this day.


 Where in the constitution does it say the federal government has any authority over electrical standards??? 
















:laughing::laughing::laughing:


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## jigs-n-fixtures (Jan 31, 2013)

IslandGuy said:


> Where in the constitution does it say the federal government has any authority over electrical standards???  :laughing::laughing::laughing:


It could be argued under the interstate commerce clause. The DOE is highly involved in interconnecting the various grids, which is lots a easier if the grids have common standards. It also makes it considerably easier on manufacturers if the voltages are standardized.


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## Meadow (Jan 14, 2011)

jigs-n-fixtures said:


> It could be argued under the interstate commerce clause. The DOE is highly involved in interconnecting the various grids, which is lots a easier if the grids have common standards. It also makes it considerably easier on manufacturers if the voltages are standardized.


But they still cant hold utilization to their own standards.


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## retiredsparktech (Mar 8, 2011)

chewy said:


> Nah, we are always 230v on each line to earth and 400 across them.
> 
> From what Ive heard the railways used big transformers in their yards and workshops to give 55v on each line to earth. They did this as a safety precaution and they imported American tools with your plugs on them so they didnt get stolen by the workers as you couldnt use them in the home workshop.


You observation regarding safety in the use of lower voltage is spot-on.
It has always been my opinion that, there is no reason to have 230 volts in a residence, for general, plug-in loads.
In the kitchen, there is a real need for higher voltage, so there should be 230 volt receptacles installed for higher wattage counter-top appliances.


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## Big John (May 23, 2010)

chewy said:


> ...From what Ive heard the railways used big transformers in their yards and workshops to give 55v on each line to earth. They did this as a safety precaution and they imported American tools with your plugs on them so they didnt get stolen by the workers as you couldnt use them in the home workshop.


 Back when they used to run incandescents in subway systems, a lot of them were Edison base left-hand-thread for that same reason.


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## JRaef (Mar 23, 2009)

IslandGuy said:


> Where in the constitution does it say the federal government has any authority over electrical standards???


Oh, one of THOSE guys...

Ok, I'll bite. It was an Executive Order by FDR. Yes, Executive Order power is not expressly mentioned in the constitution, but it has been, from the very inception of our Goverment, granted to the President by either implicit or explicit action of the Congress, referred to as "Statutory Authority". In other words the first time George Washington issued an Executive Order telling a department within the Federal Government to do something, Congress could have challenged it at that time and nipped it in the bud by asserting the lack of that ability being specifically mentioned. But those guys, intelligent enough to have CREATED an enduring democracy, understood that this kind of power was necessary, because "decision by committee" on every little detail was the fastest route to chaos and anarchy known to man.

But I suggest, Island Guy, that if you want to take it up further, start a discussion in the Off Topic section.


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## chewy (May 9, 2010)

retiredsparktech said:


> You observation regarding safety in the use of lower voltage is spot-on.
> It has always been my opinion that, there is no reason to have 230 volts in a residence, for general, plug-in loads.
> In the kitchen, there is a real need for higher voltage, so there should be 230 volt receptacles installed for higher wattage counter-top appliances.


Either has the potential to kill you, the safety aspect I meant was in a grounded metal case appliance a line to case fault only be 55v. Is higher voltage with lower current or lower voltage with higher current preferable if your going to get lit up? From what you guys describe your shocks seem more "vicous" on 110v.


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## retiredsparktech (Mar 8, 2011)

chewy said:


> Either has the potential to kill you, the safety aspect I meant was in a grounded metal case appliance a line to case fault only be 55v. Is higher voltage with lower current or lower voltage with higher current preferable if your going to get lit up? From what you guys describe your shocks seem more "vicous" on 110v.


I still feel, the higher voltage, stuns you faster.
The worst shocks that I received was from the 240 volt, corner grounded delta, system in the plant I worked at. "A" phase to ground, is a pure 240 volt shock. It's not like the power system in a home or office, where it's only 120 volts to ground.
It's well known, that there were many electrocutions, that only involved 120 volts, but those were instances where the victim was unable to break free, or any other reason, that provides a perfect path to ground.


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## Big John (May 23, 2010)

I've heard of 600VΔ being call "widow makers." A ground in those systems, intentional or not, would create the potential for a shock at full L-L voltage.

I think lower voltage systems are less hazardous than higher, but they're still hazardous.


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## LGLS (Nov 10, 2007)

Big John said:


> Back when they used to run incandescents in subway systems, a lot of them were Edison base left-hand-thread for that same reason.


 And originally, the fixtures were wired 5 in a series, or each fixture held 5 lamps, and ran on the 600v DC track voltage.


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## Meadow (Jan 14, 2011)

chewy said:


> Either has the potential to kill you, the safety aspect I meant was in a grounded metal case appliance a line to case fault only be 55v. Is higher voltage with lower current or lower voltage with higher current preferable if your going to get lit up? From what you guys describe your shocks seem more "vicous" on 110v.


How bad are 230 volt shocks compared to 120? Keep in mind we are 60Hz not 50, so that might change the way the shock feels. 


IMO the US should change to a 230 volt system, but ground the system to have 115 or 133 volts between hot to ground safety wise.


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## BababooeyHTJ (May 31, 2013)

We do use a 240v system with 120 line to ground....


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## Paulusgnome (Mar 28, 2009)

It would be interesting to see how the accidental death by mains electricity statistics compare between 110V countries and 230V countries.
If 230V is so much more dangerous, we would expect higher death rates in, say Australia or New Zealand than in the USA. I don't know for sure, but I suspect there may not be a lot of difference.


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## chewy (May 9, 2010)

meadow said:


> How bad are 230 volt shocks compared to 120? Keep in mind we are 60Hz not 50, so that might change the way the shock feels.
> 
> IMO the US should change to a 230 volt system, but ground the system to have 115 or 133 volts between hot to ground safety wise.


A carpenter had run out an extension lead through a hallway I wasnt aware of when we were up ladders pulling 240mm^2 cantols across the tray from riser to riser, I put my ladder with a worn out foot on the lead and climbed up it, I was holding on to the ladder and reached up to the cable tray and bang! Everything went black amd took me a couple seconds to register that I had been shocked, once my eyes adjusted to the low light I started losing feeling in my fingers and then my hands so I got driven to hospital with the sites defibulator onboard with me, I was diagnosed with low blood pressure but normal ECG scans etc etc. Normally I have high blood pressure and they couldnt tell me why it was so low, maybe shock from a shock I wasnt expecting. It only lasted 300ms and at 30mA as the RCD tripped and went hand to hand, pretty painful and my muscles in my upper body were sore for the rest of the day, not like accidentally lighting up a finger working live or something.


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## Meadow (Jan 14, 2011)

chewy said:


> A carpenter had run out an extension lead through a hallway I wasnt aware of when we were up ladders pulling 240mm^2 cantols across the tray from riser to riser, I put my ladder with a worn out foot on the lead and climbed up it, I was holding on to the ladder and reached up to the cable tray and bang! Everything went black amd took me a couple seconds to register that I had been shocked, once my eyes adjusted to the low light I started losing feeling in my fingers and then my hands so I got driven to hospital with the sites defibulator onboard with me, I was diagnosed with low blood pressure but normal ECG scans etc etc. Normally I have high blood pressure and they couldnt tell me why it was so low, maybe shock from a shock I wasnt expecting. It only lasted 300ms and at 30mA as the RCD tripped and went hand to hand, pretty painful and my muscles in my upper body were sore for the rest of the day, not like accidentally lighting up a finger working live or something.


 
 If it tripped an RCD that must've been well over 30ma. Sorry you had to go through that. From years of shocks lower voltages are indeed more forgiving, but given the right situation those to can do serious damage too. The irony is while our voltages are half that of the rest of the world we rarely have RCD protection of any kind on our circuits. If we get hit line to ground and it over 30ma nothing trips.


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## LGLS (Nov 10, 2007)

Paulusgnome said:


> It would be interesting to see how the accidental death by mains electricity statistics compare between 110V countries and 230V countries.
> If 230V is so much more dangerous, we would expect higher death rates in, say Australia or New Zealand than in the USA. I don't know for sure, but I suspect there may not be a lot of difference.


My understanding is that countries that utilize a 230v -> ground system also tend to use a GFCI main long before the U.S. did.


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## chewy (May 9, 2010)

meadow said:


> If it tripped an RCD that must've been well over 30ma. Sorry you had to go through that. From years of shocks lower voltages are indeed more forgiving, but given the right situation those to can do serious damage too. The irony is while our voltages are half that of the rest of the world we rarely have RCD protection of any kind on our circuits. If we get hit line to ground and it over 30ma nothing trips.


Our RCDs by law have to trip at anything over 30mA for 300ms as a minimum and 10mA and 40ms as a special purpose RCD so your quite right, he was ripping 2x4 on a tablesaw at the time so it was under load alright.


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## JRaef (Mar 23, 2009)

It's a well known fact that death occurring at 230V is far more deadly than death occurring at 120V! At 600V, you are even more dead than the death you get from 230V.


The point being, they are ALL potentially deadly, or potentially survive able, it all depends on the circumstances. The ONLY safe voltage level (over 24V) is the one you never make contact with. Beyond that, it's a crap shoot.


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