Fair point.
Harmonizing the 2nd lowest American utilization voltage.. 208 and 240v
- Thread starter Electric-Light
- Start date
- Status
Fair point.
- Occupation
- Licensed Electrician
I haven't read all the posts either. I do disagree with this slightly. There was a battle fought between Edison and Westinghouse but at the time electric power was in its infancy; it had to be sorted out somewhere. The U.S. had it first so we worked out a lot of the bugs for the rest of the world.
Also if we had had our infrastructure bombed back to the stone age after WWII we might have a straight 240V system, but we didn't so we don't.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
It should be done, the current set up I think is stupid and stuck in the past. Converting to 240 with domestic appliances would be a piece of cake for most manufacturers in that many already make 230 volt equipment overseas. Having a global voltage of 230-240 cuts stock in half.
Changing over residential would not be to hard. We already have 240, all that would be needed are 240 volt plugs and swapping to double pole breakers. Wiring wouldn't need to changed at all, the conversion can literally be done in hours. 240 gives more KW per circuit and less copper in new construction.
If houses stayed at straight 240 it will solve a mountain of problems. The fire hazards associated with open neutrals will be eradicated, stray current on ground rods and water bonds will disappear. Neutral to ground faults going unnoticed will not exist. 3 wire sub panels and neutral/ground jumping seen literally in every other install will not be of issue. Greatly simplified wiring and no more confusion. Plus 10-2 for dryers and 6-2 for ranges120 volts to ground will keep things safe as they are now.
Some would argue though having a side grounded leg at 240 would be better than a center grounded winding solely because double pole light switches would need to be used and the incandescent screw base socket would become dangerous. But as is GU24 sockets are being phased in and light switches shouldn't be used as service disconnects anyways. So 2 live legs should be a non issue.
Houses and light commercial have 5 options in the long run. 120-0-120 used as straight 240 (which will be our starting point since its already here), 0-240 which should be avoided for many reasons, 138/240Y with houses having the option of going 3 phase which in theory would increase efficiency and allow the use of 3 phase 240 AC and the final option would be 240/415Y, with houses either only getting 240 single phase or 240/415 3 phase. Utilities will love the 415 voltage in that it can travel farther meaning fewer transformers per neighborhood. 415 in houses will mean 12-3 for ranges, European ranges are 3 phase configurable as is.
Commercial will go 240/415Y. 415 is close to 480 which would mean only a slight increase in conductor size, but that almost always would be offset where 120 equipment now exists because there is no need for expensive and inefficient 480 to 120/208 step down transformers. Heavy, expensive, confusing and yup, even when no power is being drawn from the secondary the meter is still spinning with the primary pulling 140 plus watts for a 25kva unit, and of course higher with the kva. Intelli-volt fluorescent ballasts and LED drivers wont care for 277 going to 240. And fun fact, where 400 watt HPS lamps exist such as parking lot lighting and highways a simple reactor ballast can be used, just like with 150 watt and lower HPS lamps at 120 volts.
There is one irony here though, standardizing at 240 would phase out 208 with more ease, however because 277/480 is so close to 415, we will end up with dual rated 415-480 volt equipment, exactly equivalent percentage wise to our 208-240. Of course we could phase out 480, but who knows:roll:
Something else I would like to see, the NEC raising the 600 volt limit to 1000volts. I dont see 400 extra volts being an issue, but 415/718Y and a 577/1000Y would be beneficial to large commercial and industrial customers.
Also of thought would be to harmonize with the IEC colors, but that probably would never happen here.:roll:
Consumers will be the first ones on bard with this and most have money burning a hole in their pocket and they just can't wait to do this:happyno:
I also disagree with the idea it will solve stray currents on grounded objects. If properly designed, I can see some minimizing of stray currents, but if you do like is done in European countries and have a 415/230 wye system, chances are you are still grounding the midpoint of the wye, and if you put current on that conductor and ground it in multiple places like we do now, you really didn't change anything - only way to really get the most effect is to run separate grounded and grounding conductors from the source and never bond the "grounded" conductor to earth again after that point, which could also be done with what we have now and have same results on stray currents, then you have to consider that most POCO also contribute to stray current by having multiple ground connections on the current carrying neutral of their distribution system.
mbrooke
Batteries Included
- Location
- United States
- Occupation
- Technician
Depending on which system is implemented. The concept would solve stray currents if everything was straight 240, ie no neutral used as would be the case when the conversion starts, since you are re-using the old system, which already gives 240. If it the concept is ever implemented though.
Of course if we do eventually fully go 240 for standard equipment we will probably see a 240/415 Y network being used about. Utilities will probably choose a TN-C-S system as they have in place now. Of course that will cause stray currents to be the same as they are now, if not worse.
In Europe it varies from utility to utility but some use TN-C-S grounding for the 240/415 like we do here with 120/208 and 277/480 while other parts use a TN-S system which eliminates nearly all stray currents. The primary 11kv or 22kv windings regardless of the secondary grounding are mostly Delta, which eliminates stray currents on the HV neutral/ground. A good chunk of lines in the EU are 3 wire, no neutral when it comes to the HV.
Fun fact though, if everything was straight 240 or 480 volts in the US (neutrals not used for customer load), utilities could continue using a multi grounded neutral and GrY-Gr-Y 3 phase transformers with little worry regarding stray currents. When the loads are connected in delta across the secondary of a wye transformer no neutral current flows on the secondary which in turn means nearly no current on the primary neutral. Of course if a secondary phase faulted neutral/ground it would show up on the primary neutral since Y-Y passes zero sequence currents but it wont under normal non fault conditions.
But I thought this interesting:
http://www.ncbi.nlm.nih.gov/pubmed/8794957
This also for all industries.
http://www.hse.gov.uk/statistics/european/european-comparisons.pdf
I couldn't find a direct comparison with residential electrocutions but did find this shocking statistic:
- See more at: http://www.esfi.org/index.cfm/page/Injury-and-Fatality-Statistics/pid/12015#sthash.CVtytXp3.dpuf
That makes it about 10 per 10,000 of the population.
I also found this for UK.
http://www.rospa.com/homesafety/adviceandinformation/electricity/
With an estimated total of 2788, that puts it at about 4.6 per 10,000 of the population.
Last edited:
- Location
- Massachusetts
Interesting yes
On point no
Also the methods of data collection are likely as different as the side of the road we drive.
On point no
Also the methods of data collection are likely as different as the side of the road we drive.
Posted earlier by another poster.
If one country has 10/100,000 accidental electric shock accidents and another has 4.6/100,000 don't you think that might have a bearing on the point in the above quote.
Of course there is more to it than just a difference in voltages.
Possibly so, but I doubt that a two to one disparity in the specific scenario of residential accidental electric shocks can be entirely explained/blamed/accounted for by data collection methods.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Household Injuries and Accidents:
More than 30,000 non-fatal shock accidents occur each year.
I don't know how one can obtain such data and have confidence in accuracy?
I don't even know how many times I have been shocked and nobody else knew about it.
If ESFi obtained that data you'd think it came from or was extrapolated from, reported cases. I don't know.
Should you actually be admitting that?!......
But I take your point. There will be unreported, thus unrecorded, cases like yours.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
If ESFi obtained that data you'd think it came from or was extrapolated from, reported cases. I don't know.
Should you actually be admitting that?!......
But I take your point. There will be unreported, thus unrecorded, cases like yours.
I will say there is less incidents in last 10-15 years than there was before that.
May credit safer practices, may credit wiser decisions, probably some combination of both.
I agree.
And better regulation/enforcement of safer practices will most likely play a part of that.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Not much direct outside force making me follow any specific practices, mostly my own decisions on safe practices.
Or maybe not so safe practices if you have lost count of the number of times you've been electrocuted...................
mbrooke
Batteries Included
- Location
- United States
- Occupation
- Technician
In response to my conversion rant, I couldn't resist :
http://www.google.com/patents/US6328584
View attachment 9090
:http://www.google.com/patents/US6328584
View attachment 9090
OK. I said I might reply and that I mostly agreed with your post. So...
But any existing equipment that uses 120V would need to be replaced. Can be done. But maybe no small matter.
Harmonising the voltages isn't the whole story.
True - except for equipment capable of working on a range of voltages and frequencies which is typical of a lot of consumer electronics.
I suppose it could.
But any existing equipment that uses 120V would need to be replaced. Can be done. But maybe no small matter.
480/400 is 60/50Hz.
Harmonising the voltages isn't the whole story.
We, UK have had to. A very bad move in my opinion. But that is a different story for another day.
mbrooke
Batteries Included
- Location
- United States
- Occupation
- Technician
My thoughts,
OK. I said I might reply and that I mostly agreed with your post. So...
True - except for equipment capable of working on a range of voltages and frequencies which is typical of a lot of consumer electronics.
I suppose it could.
But any existing equipment that uses 120V would need to be replaced. Can be done. But maybe no small matter.
Not necessarily if dual voltage outlets were provided, but of course that would be easy to do in new construction via 14/3 and 12/3, difficult for older construction. Ease of conversion would either be dual voltage appliances or for older 120 volt ones a converter if no dual voltage outlet is present. The converter is some thing else as well. A transformer is costly and heavy
480/400 is 60/50Hz.
Harmonising the voltages isn't the whole story.
I guess you mean frequency as well, your right. Interesting thing of note most motors rated 415 50hz will work fine on 480 60hz and visa versa from an electro magnetic flux saturation stand point. Higher voltages with a higher frequency reduce the risk of stator windings saturation. Problem is a 60hz 415 rated motor will not be to lucky at 50hz 415. And so many large motors in the United States are rated 480 volts and must be at 1,800 rpm so abolishing 480 volts will be hard, and going to 50hz will be insane. 208 will be fairly easy to abolish, however if 415 does get a start here, 480 wont be leaving any time soon. You do have a good point though, frequency wise we will still need 2 separate motors and so fourth. Even saturation aside rpm in most application makes a difference.
We, UK have had to. A very bad move in my opinion. But that is a different story for another day.
I think I know what your referring to. And oh, yahhh, that was a dumb thing to do. If I remember black used to be the neutral but is now a phase and blue used to be the C phase but now is the neutral.:slaphead: Hope I got it right
I thought the point of the discussion was to simplify the system to one voltage.
I wasn't suggesting the implementation of 50Hz in the US. Just that voltage harmonisation isn't the whole story.
EU madness in my opinion. And no, coloured tape isn't a solution.
mbrooke
Batteries Included
- Location
- United States
- Occupation
- Technician
Simplifying the voltage is the goal of course, however when we start out with that we will technically have 2 utilization voltages in that older 120 volt equipment will still exist. Often its not practical to just get rid of the 120 at once. After that though we will have only 1 standard for household appliances.
"Just that voltage harmonisation isn't the whole story." Im wondering about this, at least your thoughts on it.
In my opinion the older British wire colors were better. Ive seen the wire colors Brown, Black, Gray but to admit it they look so dull that its difficult to tell them apart given dim light, color variants or dirt on the wire. Red yellow and blue are way easier to pick out.
I don't think it's entirely practical to get rid of the 120V in the short term. And it might never happen.
Frequency - 480/400 is the same ratio as 60/50. It The same voltage ratio results in the same flux for wound components. Motor speeds are different of course.
It's madness. Especially when you look at the old/new interface.
- Status