US Electrician qualifications for a Brit

snipped-for-privacy@ipal.net wrote:


By "advanced" do you mean someone placed in the 3rd, 4th or 5th year, is so they take several. In fact a few years back we had the largest non-union shop in the area sign with the union. All of their employees were tested into the program. Some in the 1st year, and some cam in as journeymen.

Yes we would, but the same rule would apply, they would have to be tested to see what their qualifications are.

I agree, the union does do some certification in areas such as welding, communications, fiber optics and such. They have nothing to do with licensing in this area.
Other than the local community collage, there really isn't anyplace to get good training upto the industrial level.
Enginners are usally considered management, and I can't think of any place they were part of a trade union.
Many large companies have several unions in place. One I know of were I have performed work has 12 differant unions.

A few weeks back there was a poster who asked where else he could go because the IBEW turned him down. By his own admission he was week in algabra. This is a requirement placed on us by the government for the program, not the union. Why give up, go to night school, take the class and apply again.
There have also been people who don't make the first cut, and walk away. My first year we took in 36 apprentices, one of the largest classes at the time. Since then we have had classes in the 40's.

Having worked a few conventions in the upsate area, I can relate to the issue. Everyone see a "plug" and says "there's power right over there". But what is that backbone of that circuit? How many "plugs" are on the circuit, and how much is connected to it? Where did the "exhibitor" run his extention cord?
I'll have to dig out some of the pitchers I have of the fires under capret, behind a wall of boxes just to name a few place. Sadly, the exhibitor just want to get set up and market his product. If he has little or no concern for how he connects his equipment, the result can (and has been) a fire, or the loss of power to all of the other exhibitors. The you have to tear through the piles of boxes stashed behind or in back of the both to see who has what plug in so that you can get power back to everyone else. Some of these people come in with 5000 watts of quartz lights!!!!! They only get to "share" a 20 amp circuit!!!!
So I can see where an electrician would want to dictate who get to make any connection. It's the only way he can know whats getting connected, and control the power usage.

I agree, sadly there is no public program.

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The engineers at Boeing are unionized.
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Are the US contributers to this thread aware that the grounded current carrying conductor is black in UK practice, Edison circuits are unknown there, RCDs are used to protect several circuits rather than using GFCIs to protect one circuit. There are real differences between the two nations common electrical practice. No matter how skilled the electrician is when you immigrate to another continent you will have to do some catch up to be skilled in the new environment. There are training programs in most areas in both the union and nonunion environment. The union affiliated training programs are paid for jointly by the unions membership and by the employers. The nonunion programs are paid for entirely by the trainee in most cases.
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| Enginners are usally considered management, and I can't think of any | place they were part of a trade union.
I know that's the common situation. But they are in fact NOT management in most companies. The fact that they are typicaly doing design work as opposed to actual installation should not be considered as making them management. That's distinct from those who actually do also take on a management role by becoming a supervisor or something like that. But if an engineering is merely overseeing that the work matches the design, as opposed to overseeing electrician staff directly, then I see no cause to consider them management. And I have heard of some that _want_ to be in a union for better protection from their management.
|> Most people don't want to. But if not being able to get in means you |> have to find some other job right now, it might end up being that you |> can't ever get in due to the vicious circle thing. If you have to get |> in to get work, and you have to get work to get experience, and you |> have to be in to get work, well, hopefully, you can see where that leads. | | A few weeks back there was a poster who asked where else he could go | because the IBEW turned him down. By his own admission he was week in | algabra. This is a requirement placed on us by the government for the | program, not the union. Why give up, go to night school, take the class | and apply again.
If not knowing the algebra can still allow one to do certain work at a certain level, then someone doing that work should be eligible to join a union ... being recognized at that level. Of course, if there is no work for someone at that level, the union wouldn't need to be supporting his employment relationship.
|> | So DANA. please enlighten me as to your expertise as to why the IBEW is |> | such a bad organization that you can claim that a person you know |> | nothing about "ripped off the customer, and returned marginal at best |> | performance" |> |> I have seen some problems with unions. But I find it is the exception |> rather than the rule. In most cases it is the result of very problematic |> companies and the overly detailed agreements that come about, making for |> too many rules for everyone to follow. I know of a case where in New |> York at certain convention areas, they require an electrician just to |> plug anything into an electric outlet. Electricians are needed to wire |> up the outlets. But they all walked out one time about 15 years ago when |> one of the show exhibitors plugged in his own computer (because he had |> to unplug it to reset it, and needed to plug it right back in, and an |> electrician happened to see him do it). It's things like that which do |> give unions a bad name. I suspect the mafia was highly involved; it is |> New York, afterall. | | Having worked a few conventions in the upsate area, I can relate to the | issue. Everyone see a "plug" and says "there's power right over there". | But what is that backbone of that circuit? How many "plugs" are on | the circuit, and how much is connected to it? Where did the "exhibitor" | run his extention cord? | | I'll have to dig out some of the pitchers I have of the fires under | capret, behind a wall of boxes just to name a few place. Sadly, the | exhibitor just want to get set up and market his product. If he has | little or no concern for how he connects his equipment, the result can | (and has been) a fire, or the loss of power to all of the other | exhibitors. The you have to tear through the piles of boxes stashed | behind or in back of the both to see who has what plug in so that you | can get power back to everyone else. Some of these people come in with | 5000 watts of quartz lights!!!!! They only get to "share" a 20 amp | circuit!!!! | | So I can see where an electrician would want to dictate who get to make | any connection. It's the only way he can know whats getting connected, | and control the power usage.
It sounds like something seriously wrong with that installation. I've worked a few shows like that myself, and even been involved in the forms submitted. The available power was always a WHOLE 15 amp or 20 amp 120 volt circuit to a standard size booth. Options were sometimes available to have other levels of power hooked up, usually requiring one or two weeks written advance notice, and somethings with extra charges such as installation and/or power consumption.
If someone comes in and brings 5000 watts of quartz lights and their breaker goes off, then whose fault is that?
I simply cannot agree with you. But this is based on well run shows I have exhibited and/or attended ... NONE of which were ever in New York, or ever required an electrician to plug anything in, or ever had any problem. I do recall once an adjacent booth losing power and their coordinator had to track down an electrician to reset the circuit.
I'll continue to advise people to avoid New York for their shows. The power seems to get wired up better in other cities. Maybe the facilities in New York just don't have the capacity?
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again
electrician.
get
on
I took that as being licensed.

Where I was surprised to find out that Electricians are not tested/licensed by the state.

That is a different topic.

I was in a union. One of the Jobs up here required you to be a teamster. I left that job to do a contract in Iraq, and have just returned. I am not an electrician, I am a electronic tech/communication tech. I read this newsgroup for the info that is presented.

If you must know, another job I was in wanted to unionize, and the IBEW seemed to work with management more than the workers, hence the union drive failed.

Nope, nothing like that at all. I am in a non union position

See above. And I actually did not address any union.

Just because a person is in a union does not mean the work is any better than a non union person, you can find both good and bad inside and outside of a union.

I had thought the state of NY licensed its electricians, something like a NICET exam or some such, and you would not need be a union member to take the test. My reply was really not a knock against the unions, why you became so defensive is open to questions.

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Dana wrote:
My reply was really not a knock against the unions, why you became so defensive is open to questions.
Dana wrote:
Another one who ripped off the customer, and returned marginal at best performance.
In Reply to:
For one thing many IBEW union electricians are retiring with more income than many nonunion electricians earn. I am one such electrician.
If that was not a "knock" against unions, then I guess I don't know what one is.
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Dana wrote:

You're the one who used words like propaganda.
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"This alternating current stuff is just a fad. It is much too dangerous
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| My reply was really not a knock against the unions, why you became so | defensive is open to questions.
It sure came across that way pretty strongly.
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| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
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Dana wrote:

It's not just a question of getting licenced, as the OP seems to recognise. There's a great deal of difference between the UK and the US where electrics are concerned, it's not just a question of Voltage and frequency being different. It wouldn't be a case of starting from scratch, but some re-training would certainly be required. Electrons may behave the same, but there's a great deal of difference in electrical installation practice, terminology and regulations between the two countries.
It would be unwise to assume that something in another country works the way you expect it to.
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On 10 Oct 2006 08:20:43 -0700 snipped-for-privacy@mail.croydon.ac.uk wrote: | | Dana wrote: | |> The OP was not an apprentice, hence he was only looking for a place to get |> licensed. |> I myself was surprised to see that NY does not license the electricians on |> the state level, I assumed most states ensured the electricians were |> qualified. | | It's not just a question of getting licenced, as the OP seems to | recognise. There's a great deal of difference between the UK and the | US where electrics are concerned, it's not just a question of Voltage | and frequency being different. It wouldn't be a case of starting from | scratch, but some re-training would certainly be required. Electrons | may behave the same, but there's a great deal of difference in | electrical installation practice, terminology and regulations between | the two countries.
They don't use wire nuts in UK. They use choc-blocks, and kind of terminal base. Those could be used here, but it just isn't common. That's just one of the examples. He would have to become more intimate with things like the split single phase circuit, and forget all about ring circuits. And he would have to quit trying to pick the non-existant fuse out of the plug to see why something isn't working.
| It would be unwise to assume that something in another country works | the way you expect it to.
Oh, I bet ring circuits would work fine here. He'd have to learn what that red tag means, too :-)
It's probably a lot more about the common practices. Electrons don't care about the color of insulation. But installation practices sure do in both countries. And the colors are different. Old habits might die hard. You might have to watch out for grounding that blue wire.
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snipped-for-privacy@ipal.net wrote:

Are you aware that our colours have recently changed? Red, yellow and blue have now become brown, black and grey (don't blame me, I didn't choose the colours!) black has become blue. That means that what used to be a phase colour (blue) is now neutral, and what used to be neutral (black) is now a phase. A special warning label, I don't know the exact wording, has to be placed on any installation where both old and new colours are found together.
I'm not an electrician, but I'm amazed at how much difference the is between the two countries; It's difficult to find things that are the same. With the exception of the new European harmonised colours it does seem to me that things are much simpler here than they are over there, where things really do seem over-complicated. To start with, take Voltage; over here, unless you're running something really big, like a steelworks or an electric railway, it's 415 phase to phase, 240 phase to neutral (I should call it 400 and 230 now, but old habits die hard, and nothing's really changed). Over there it's 120, 208, 240, 277, 347, 480 or 600; have I missed any out? It can be wye (we would call it star) or delta. If it's delta it can be that strange centre-grounded system where two of the wires are 120 to ground, and the third is 208, so the three phases are not all the same. Then what on Earth is open delta? I've heard of it, but I've never found anybody who can tell me what it is.
Then there are the plugs and sockets. Our normal 13A one is BS1363, and they're all the same. For industrial use, there's what was BS4343, which now has a EN number which I can't remember. They come in 16, 32, 63 and 125A versions, are colour coded for Voltage, and have three, four or five pins, but in each case a higher current one is like a lower current one, except that it's larger. Over there you seem to have the same things, called pin and sleeve devices, but rated at 20, 30, 50 and 100A for some reason. You also have orange ones for combined 120/240V and grey, which I think are 480V, which we don't have here. Before BS1363 we had BS456, which had round pins, there were four ratings, 2, 5, 15 and 30A. Again, they were all similar, except for size. They are little used now, excepr the 5 and 15A ones for stage lighting.
Over there you have the NEMA range; where do we start with those, it's truely bewildering. Obviously, you need many different versions for the various Voltages in use there, but then look at the current ratings: 15, 20, 30, 50 and 60A. Here there is generally a difference of 2-3X between sizes; there you have five ratings just to cover a range of 4:1. Then there seems to be little pattern to the various versions. Take the 15A ones; the 5-15 has vertical pins, increase the Voltage and the 6-15 has horizontal ones. If you need 277V the 7-15 has them at an angle, between those of the 5-15 and the 6-15. Then look at the 20A ones, why have two ratings so close together? The 5-20 logically ought to look like a 5-15, but larger. It doesn't of course, the neutral pin is turned horizontal. the 6-20 doesn't look like a 6-15 either, the neutral pin is turned vettical, so the 5-20 and the 6-20 each have one horizontal and one vertical pin, but the opposite way round, so the orientation of the pins sometimes indicates Voltage, and sometimes current. The 20A receptacles have 'T' slots, so they can also take 15A plugs, except in Canada, where they don't. I've never seen a 7-20, but I believe it's similar to a 7-15, but with one pin slightly wider. I don't think my brain can cope with the 30-60A ones, with their 'L' shaped pins etc. Then there are the locking range, which are totally different, not to mention the various non-Nema ones.
Then consider the number of pins on a plug; over here it can be:
2 pin L,N (shavers and toothbrushes only). 3 pin L,N,E. 4 pin L1,L2,L3,E 5 pin L1,L2,L3,N,E.
over there they can be:
2 pin hot, neutral or hot, hot. 3 pin hot, neutral, ground or hot, hot, ground or hot, hot, neutral or hot, hot, hot. 4 pin hot, hot, nuutral, ground or hot, hot, hot, neutral or hot, hot, hot, ground. 5 pin hot, hot, hot, neutral, ground.
I think that's covered all the possible combinations, with each having it's own NEMA configurations of course.
The whole thing just seems to be incredibly complicated; there must be an awful lot to learn to be an electrician over there.
A couple of things you might be able to tell me:
What colours are used for a three phase installation over there?
I believe a fairly large customer, say a shopping mall or a large office building, or large railway station for example would be likely to have a three phase 480/277V supply. I assume that large plant, HVAC, elevators etc. would probably be driven by 480V three phase motors, and I know that large discharge lighting installations are often 277V, but they would also need 120V for things like office equipment, and small lighting. Obviously you cannot get this by connecting directly to the 480/277V supply. Does the electricity company provide them with a separate 120V supply, or does the customer just get 480/277, and they provide their own step-down transformer? In either case is it centre-tapped 120-0-120V, as in a domestic installation, or just a simple 120V?
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WOW, you have lot to reply to in one post!
wrote:

120V is used for all common loads.
208V is three phase wye with 120V to neutral. This would be the norm with new installations that don't justify the higher voltage of 480 or 600. It's common for light commercial. It's also used extensively in industrial and commercial for the smaller loads, internally supplied through a transformer from higher voltage.
240V can be either single phase, or the three phase delta you mentioned below. The single phase 120/240 is norm for residential. The delta can be corner grounded, ungrounded or center tapped. All 240V three phase services are not preferred and are falling out of favor.
480Y/277 three phase is the norm for industrial and heavy commercial in the US. As you note, discharge lighting is often powered from 277.
A special class is resistance grounded 480Y. Used where reliability is of extra importance. Can only be used with line to line loads. The resistance ground allows temporary operation with a ground fault.
480V single phase is sometimes used for street lighting. 480V delta, either ungrounded, corner grounded or center tapped ground is used in historical industrial installations. Again not preferred for new installations.
600Y/347 is used as the normal industrial voltage for Canada. In Canada, the 347V is used for discharge lighting. The voltage is used in the US in some heavy industry for the higher power capability. 347V can not be used for discharge lighting in the US (against code) in most circumstances.

The center tapped delta is common where there are mostly single phase loads and a small amount of three phase load. It gives 240V three phase, plus 120V and 240V. The 120V/240V can be wired just like a regular house / light commercial installation.
Open delta is where one transformer is removed. Only two are used for three phase. Since the transformer for the 120/240 leg is supplying the larger load, it will be a large transformer. A single smaller one can supply the limited three phase load.
Delta and open delta cause problems for the utility.
Often the delta is connected with either ungrounded wye or delta on the primary. This can cause problems with ferroresonance or backfeed when one phase is lost.
Open delta is usually connected wye to delta. The single phase loads are OK, but the three phase draw is converter to a lower power factor on the line side.
For these reasons, the switch to 208Y/120 is pushed.

The pin and sleeve connectors aren't used that much here. It's more common to just hard wire.

Most of the time, all you ever see is the 5-15, 5-20, 14-30 & 14-50. Locking is used quite a bit in industry. Check out the 30TT! Many times an electrician thinks it's a 10-30 (no longer allowed) since the only difference is in the ground plug. The poor recreational vehicle owner then gets everything fried because it's 120V, not 240V!

Green or green yellow is earth. The green / yellow is there for harmonization, but it little used.
White, white with colored stripes or number, or gray for neutral. White is most common. The colored stripes, gray or numbers are used where multiple voltages are present in one building. This keeps the different voltages separated - it would be common to have 208Y/120 and 480Y/277 in the same raceway for example. In this case, the most common would be to have the white the 208Y/120 neutral, and a gray 480Y/277 neutral.
The code allows any colors to be used for phase conductors except white, gray or green, but practice is:
120V - black 120/240V black & red 208Y/120 black, red, & blue 240V delta CT: low legs black & red, high leg orange. <-note that orange is required in the code. 480Y/277 brown, orange, yellow
In places where they keep track of phase sequence (and not all do), the colors are in phase sequence order.

Unless they take service at higher voltage. Medium votlage service (defined as between more than 600V and less than 35kV) is much more common in NA.

It can happen if there is an upgrade and the lower voltage was original. Usually it will be 120/240 single phase or 208Y/120 three phase. 120V only isn't normally used.
, or does the customer

That would be the case most of the time.
In

120/240 or 208Y/120. It's the choice of the customer. Both are common. The 208Y/120 probably is more often used.
Straight 120 isn't that common, except where the load would be extraordinarily small, a single outlet for example. 120V is common in control circuits on the other hand. The higher voltages are not permitted in control wiring.
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And just think. You don't even need to be licensed. Wonder when blighty will be like this - probably the year NEVER. Unless your claiming asylum that is!!
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On 10 Oct 2006 12:04:36 -0700 snipped-for-privacy@mail.croydon.ac.uk wrote: | snipped-for-privacy@ipal.net wrote: | |> It's probably a lot more about the common practices. Electrons don't care |> about the color of insulation. But installation practices sure do in both |> countries. And the colors are different. Old habits might die hard. You |> might have to watch out for grounding that blue wire. | | Are you aware that our colours have recently changed? Red, yellow and | blue have now become brown, black and grey (don't blame me, I didn't | choose the colours!) black has become blue. That means that what used | to be a phase colour (blue) is now neutral, and what used to be neutral | (black) is now a phase. A special warning label, I don't know the | exact wording, has to be placed on any installation where both old and | new colours are found together.
Well, then I was right, at least with respect to the new colors. I just don't know if the OP worked with the new colors or the old ones. If he did work with the new ones, he might well bond the blue wire to ground, which would be wrong here, but right there.
| I'm not an electrician, but I'm amazed at how much difference the is | between the two countries; It's difficult to find things that are the | same. With the exception of the new European harmonised colours it | does seem to me that things are much simpler here than they are over | there, where things really do seem over-complicated. To start with, | take Voltage; over here, unless you're running something really big, | like a steelworks or an electric railway, it's 415 phase to phase, 240 | phase to neutral (I should call it 400 and 230 now, but old habits die | hard, and nothing's really changed). Over there it's 120, 208, 240, | 277, 347, 480 or 600; have I missed any out? It can be wye (we would | call it star) or delta. If it's delta it can be that strange | centre-grounded system where two of the wires are 120 to ground, and | the third is 208, so the three phases are not all the same. Then what | on Earth is open delta? I've heard of it, but I've never found anybody | who can tell me what it is.
Open delta is delta with one of the windings missing. You still get the same voltage at the same phase across the points with the missing winding, but you are getting it from the other two windings. One advantage of open delta is it won't backfeed. But then, that's an advantage wye/star, too. You have to derate open delta because all three phases are pulling from just 2 windings.
Yes, it is a complex mess of voltages over here. Some old guy that was messin' with light bulbs over 100 years ago decided to split the circuit in half at 110 volts because it made his bulbs last longer. He could have used the 127 volts that was there in the star 220/127 volt systems, except for the fact that he was dead set on using DC instead of AC.
I'd be just as happy if they would switch all the power here to 480/277. Of course doing that today would be such a mess. They wouldn't be able to get rid of the 120 volt stuff for many decades. But at least incandescent lights could be run on 12 or 24 volts very effectively, and fluorescent could be run on 277 directly.
The 208 volt thing is a messy issue. Many offices, as well as apartments in large buildings, have that instead of 240. Unless you change out the burner elements, expect it to take a bit longer for the water to boil at the highest temperature (though at lower settings, it's thermostat driven, so it just changes how long the element stays on).
BTW, if you took a transformer designed for 480 or 277 volts at 60 Hz, and wanted to run it at 50 Hz, guess what the voltage would then have to be. Yup, 400 or 230. I bet that's not a coincidence.
| Then there are the plugs and sockets. Our normal 13A one is BS1363, | and they're all the same. For industrial use, there's what was BS4343, | which now has a EN number which I can't remember. They come in 16, 32, | 63 and 125A versions, are colour coded for Voltage, and have three, | four or five pins, but in each case a higher current one is like a | lower current one, except that it's larger. Over there you seem to | have the same things, called pin and sleeve devices, but rated at 20, | 30, 50 and 100A for some reason. You also have orange ones for | combined 120/240V and grey, which I think are 480V, which we don't have | here. Before BS1363 we had BS456, which had round pins, there were | four ratings, 2, 5, 15 and 30A. Again, they were all similar, except | for size. They are little used now, excepr the 5 and 15A ones for | stage lighting. | | Over there you have the NEMA range; where do we start with those, it's | truely bewildering. Obviously, you need many different versions for | the various Voltages in use there, but then look at the current | ratings: 15, 20, 30, 50 and 60A. Here there is generally a difference | of 2-3X between sizes; there you have five ratings just to cover a | range of 4:1. Then there seems to be little pattern to the various | versions. Take the 15A ones; the 5-15 has vertical pins, increase the | Voltage and the 6-15 has horizontal ones. If you need 277V the 7-15 | has them at an angle, between those of the 5-15 and the 6-15. Then | look at the 20A ones, why have two ratings so close together? The 5-20 | logically ought to look like a 5-15, but larger. It doesn't of course, | the neutral pin is turned horizontal. the 6-20 doesn't look like a | 6-15 either, the neutral pin is turned vettical, so the 5-20 and the | 6-20 each have one horizontal and one vertical pin, but the opposite | way round, so the orientation of the pins sometimes indicates Voltage, | and sometimes current. The 20A receptacles have 'T' slots, so they can | also take 15A plugs, except in Canada, where they don't. I've never | seen a 7-20, but I believe it's similar to a 7-15, but with one pin | slightly wider. I don't think my brain can cope with the 30-60A ones, | with their 'L' shaped pins etc. Then there are the locking range, | which are totally different, not to mention the various non-Nema ones. | | Then consider the number of pins on a plug; over here it can be: | | 2 pin L,N (shavers and toothbrushes only). | 3 pin L,N,E. | 4 pin L1,L2,L3,E | 5 pin L1,L2,L3,N,E. | | over there they can be: | | 2 pin hot, neutral or hot, hot. | 3 pin hot, neutral, ground or hot, hot, ground or hot, hot, neutral | or hot, hot, hot. | 4 pin hot, hot, nuutral, ground or hot, hot, hot, neutral or hot, | hot, hot, ground. | 5 pin hot, hot, hot, neutral, ground. | | I think that's covered all the possible combinations, with each having | it's own NEMA configurations of course. | | The whole thing just seems to be incredibly complicated; there must be | an awful lot to learn to be an electrician over there.
Wow, you covered the mess quite effectively.
About the only consistency I have seen in the NEMA plug patterns is that a 6-15 plug will fit into a 14-15 outlet with the correct wiring. But they didn't seem to do that with any other amperage.
Personally, I don't really like the BS1363. I would prefer the Schuko over either what is in UK or US. OTOH, if I were to design it, I'd have a plug with a metal shroud that doubled as ground, with the neutral being a round pin in the center, and each phase in three phase systems being a pin at 120 degrees around a circle. Outlets with only single phase would only have openings at the center and one end if they were L-N, and just the two ends if they were L-L. Plugs could match the load and be able to fit any outlet with the correct type of phases available. A higher voltage would be a large plug with pins further apart. I'd probably use blades rather than round pins for the phase lines, and make the blades wider (not thicker) for higher amps (and only in L-L).
I would definitely have chosen 60 Hz or even higher if I were to have designed the system. I would keep a higher voltage, but require incandescent lights be run on 32 volts or less.
| A couple of things you might be able to tell me: | | What colours are used for a three phase installation over there?
208Y/120: HOT: black, red, blue NEUTRAL: white 480Y/277: HOT: brown, orange, yellow NEUTRAL: gray Grounding: green Isolated ground: green/yellow combination
The colors are not all in the NEC. Neutral and ground are, as is the one higher voltage wire of that center tapped delta 240 system (2 hots are 120 volts at 180 degrees from each other, and one more hot is 208 volts at 90 degrees, forming a delta) has to be orange. Some other rules exist about using distinctive colors for phases, but the exact colors are not specified. Some local areas do specify specific colors and those are not always the same. For example in Austin Texas, 480Y/277 uses purple for one of the colors
| I believe a fairly large customer, say a shopping mall or a large | office building, or large railway station for example would be likely | to have a three phase 480/277V supply. I assume that large plant, | HVAC, elevators etc. would probably be driven by 480V three phase | motors, and I know that large discharge lighting installations are | often 277V, but they would also need 120V for things like office | equipment, and small lighting. Obviously you cannot get this by | connecting directly to the 480/277V supply. Does the electricity | company provide them with a separate 120V supply, or does the customer | just get 480/277, and they provide their own step-down transformer? In | either case is it centre-tapped 120-0-120V, as in a domestic | installation, or just a simple 120V?
The customer or landlord usually provides a transformer to step down from 480/277 to get 120. But it is usually done as a 208/120 three phase step down to keep the loads balanced on the phases. But in smaller cases, that step down could just be single phase, taking 480 to a transformer and getting 120/240 (120-0-120) out. The simple 120 volt 2-wire system is very rare. Voltage drop is worse on 120 volts than on 240 volts. But by splitting the loads across 2 phases like that, you cut the current in half and the impact of voltage drop is reduced.
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On 10 Oct 2006 12:04:36 -0700 snipped-for-privacy@mail.croydon.ac.uk wrote:
| Over there you have the NEMA range; where do we start with those, it's | truely bewildering. Obviously, you need many different versions for | the various Voltages in use there, but then look at the current | ratings: 15, 20, 30, 50 and 60A. Here there is generally a difference | of 2-3X between sizes; there you have five ratings just to cover a | range of 4:1. Then there seems to be little pattern to the various | versions. Take the 15A ones; the 5-15 has vertical pins, increase the | Voltage and the 6-15 has horizontal ones. If you need 277V the 7-15 | has them at an angle, between those of the 5-15 and the 6-15. Then | look at the 20A ones, why have two ratings so close together? The 5-20 | logically ought to look like a 5-15, but larger. It doesn't of course, | the neutral pin is turned horizontal. the 6-20 doesn't look like a | 6-15 either, the neutral pin is turned vettical, so the 5-20 and the | 6-20 each have one horizontal and one vertical pin, but the opposite | way round, so the orientation of the pins sometimes indicates Voltage, | and sometimes current. The 20A receptacles have 'T' slots, so they can | also take 15A plugs, except in Canada, where they don't. I've never | seen a 7-20, but I believe it's similar to a 7-15, but with one pin | slightly wider. I don't think my brain can cope with the 30-60A ones, | with their 'L' shaped pins etc. Then there are the locking range, | which are totally different, not to mention the various non-Nema ones.
For a mix of some different receptacles: http://phil.ipal.org/usenet/aee/2006-10-11/mix.html
For 277 volt 15 amp and 20 amp: http://phil.ipal.org/usenet/aee/2006-10-11/277.html
So, if we could scrap the whole system, or better yet, if you invented a time machine and could go back and create a standard for the whole world, how would you do it?
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snipped-for-privacy@ipal.net wrote:

That's a good question, isn't it? If I can have the time machine can I take my present-day knowledge back with me? When Edison designed his 100V d.c. sytem it made sense in terms of the requirements at the time. Small incandescant lamps were about the only load. and generators were small, serving a small area, with short transmission distances, and the full output current being capable of being taken out via the brush gear of a dynamo. God solution at the time. Where he got it wrong, and where the Westinghouse/Tesla camp got it right is that they designed a system with a future; one that could be developed into the sort of power systems we have today, which span countries and continents, and connect 500MW generators and multi-MW motors. The Edison system was a dead end, but if I couldn't take my knowledge back with me I might well design something similar. Even with that knowledge, there were applications in the past which might have required a different system, but which are obsolete today, and therefore no longer required.
Firstly, I would try to get a common worldwide standard. Enables people to move equipment from place to place, enables manufacturers to sell the same product in different markets, reduces the risk of people making mistakes with an unfamilar system, and makes life easier for people like the OP in this thread, who need to work in different locations.
Just about every power system in the World is three phase a.c., and I see no reason to do otherwise.
Voltage. There seem to be two main camps at the moment, Japan, USA, Canada, Mexico, I think parts of South Americatoo, all in the 100-130V range, phase to neutral, and just about everywhere else on 220-240. About the only application where the lower range is better is incandescant lighting, which is well on the way to extinction in industrial and commercial use, and rapidly going the same way in the home. Small decorative lamps, and halogens are better run at a much lower Voltage anyway, and the transformer for this can work equally well on either Voltage, so I'd go for something towards the upper end, in the 200-300V range. Considerable savings in copper, less risk of connectors running hot, and possible fire risk with the lower current. No need for extra insulation; that on existing cables is determined by physical requirements, and is quite adequate for either Voltage.
Frequency. Just about everywhere is either 50 or 60 Hz. now. Applications for which lower frequencies were used, mainly transport related, e.g. rotary converters providing d.c., and a.c. series wound traction motors are almost extinct, so I see no reason to go lower. I would choose at least 60 Hz., possibly 75. Probably not higher, due to domestic equipment with series wound universal motors. Higher frequency is a disadvantage with very long transmission lines, but these days high Voltage d.c. is a possible solution in this case.
I would supply three phase to homes; in this country all three phases are taken, at low Voltage, down each street, and houses are fed alternately from each phase. I believe that in some cases all three phases are actually taken into each house, but only one is normally actually connected to anything. So near and yet so far.
Plugs and sockets. To be honest, I can see problems with all of them. You said: "Personally, I don't really like the BS1363." What don't you like about them? They are painful if one is on the floor, with pins up, and you tread on it with bare feet! They are quite large, but not much more so than a Schuko. I like the internal fuse, essential on a 30A ring circuits of course, but would have preferred to see different sizes for different ratings; that would have required different plugs of course, but would prevent fitting the wrong value fuse. I like the shuttered outlets, and the shrouded pins. Not perfect, but not a bad design. There was one strange problem with it; a one penny coin will fit exactly between the three pins, and will touch all three. In the days before the shrouded pins a practical joke was to place a coin in this position, put the plug in a socket, and wait for somebody to switch on. Most British sockets have a switch. The pins are nice silid lumps of brass, expenive of course, and well capable of carrying well over 100A, but they don't bend, have a large gontact area for a good, low-resistance connection, and there's plenty of metal to allow some to be removed at the base of the pins, to allow the plastic shrouding; you couldn't do that with a NEMA, the metal just isn't thick enough.
I've just seen what the time is; I've got to go and project at the local cinema, just a few hours while somebody is away, I'll finish when I get back.
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On 11 Oct 2006 05:49:22 -0700 snipped-for-privacy@mail.croydon.ac.uk wrote:
| snipped-for-privacy@ipal.net wrote: | |> So, if we could scrap the whole system, or better yet, if you invented a |> time machine and could go back and create a standard for the whole world, |> how would you do it? | | That's a good question, isn't it? If I can have the time machine can I | take my present-day knowledge back with me? When Edison designed his | 100V d.c. sytem it made sense in terms of the requirements at the time. | Small incandescant lamps were about the only load. and generators were | small, serving a small area, with short transmission distances, and the | full output current being capable of being taken out via the brush gear | of a dynamo. God solution at the time. Where he got it wrong, and | where the Westinghouse/Tesla camp got it right is that they designed a | system with a future; one that could be developed into the sort of | power systems we have today, which span countries and continents, and | connect 500MW generators and multi-MW motors. The Edison system was a | dead end, but if I couldn't take my knowledge back with me I might | well design something similar. Even with that knowledge, there were | applications in the past which might have required a different system, | but which are obsolete today, and therefore no longer required.
Yes, take back the knowledge of power systems and safety. You can't really do it better if you don't take something back.
| Firstly, I would try to get a common worldwide standard. Enables | people to move equipment from place to place, enables manufacturers to | sell the same product in different markets, reduces the risk of people | making mistakes with an unfamilar system, and makes life easier for | people like the OP in this thread, who need to work in different | locations.
Yes, fully universal would be a good thing.
| Just about every power system in the World is three phase a.c., and I | see no reason to do otherwise.
Single phase is cheaper in rural areas. But maybe a usable compromise is to rule out ground return systems, which means you have to have at least 2 wires, and use 2 line wires out of the 3 for single phase. Then you can at least get the same ratio between L-N and L-L as you get with real three phase. But then, three phase is just one more wire, and allows the 3 wires to be a bit thinner to serve the same area.
| Voltage. There seem to be two main camps at the moment, Japan, USA, | Canada, Mexico, I think parts of South Americatoo, all in the 100-130V
And Taiwan.
| range, phase to neutral, and just about everywhere else on 220-240. | About the only application where the lower range is better is | incandescant lighting, which is well on the way to extinction in | industrial and commercial use, and rapidly going the same way in the | home. Small decorative lamps, and halogens are better run at a much | lower Voltage anyway, and the transformer for this can work equally | well on either Voltage, so I'd go for something towards the upper end, | in the 200-300V range. Considerable savings in copper, less risk of | connectors running hot, and possible fire risk with the lower current. | No need for extra insulation; that on existing cables is determined by | physical requirements, and is quite adequate for either Voltage.
Wall switches for the most part are used for lighting. They like to be cheaper as single pole, which means the lights need to run L-N. And if that Edison screw base is to be used, L-N is more important.
But I'd prefer a L-L connection for just about everything else.
If L-N is kept at a low voltage suitable for incandescent lights and L-L is run at a much higher voltage, these would then have to be separate systems (e.g. a small transformer in the home to create the low voltage for the lights). If these are kept separate, then the different ratio between L-N and L-L for single vs. three phase is no longer an issue (the L-L would be made from 2 different L-N voltages depending on whether the distribution source is single or three phase, but these voltages would not be directly used, and so would not be a basis for equipment utilization voltage).
For example, 24 volts L-N for lights (fixed and pluggable) and small loads (shaver, wall warts). Then 288 volts L-L for big loads (this would be 144 volts relative to ground for single phase source, or 166 volts relative to ground for three phase source). The transformer to convert 288 to 24 would be a 12:1 winding ratio. 12 volts would also be lighting option.
| Frequency. Just about everywhere is either 50 or 60 Hz. now. | Applications for which lower frequencies were used, mainly transport | related, e.g. rotary converters providing d.c., and a.c. series wound | traction motors are almost extinct, so I see no reason to go lower. I | would choose at least 60 Hz., possibly 75. Probably not higher, due to | domestic equipment with series wound universal motors. Higher | frequency is a disadvantage with very long transmission lines, but | these days high Voltage d.c. is a possible solution in this case.
I, too, would go with 60 to 75 Hz.
That would eventually impact TV standards, too :-)
| I would supply three phase to homes; in this country all three phases | are taken, at low Voltage, down each street, and houses are fed | alternately from each phase. I believe that in some cases all three | phases are actually taken into each house, but only one is normally | actually connected to anything. So near and yet so far.
I would make three phase optional. With my L-L preference, three phase is just one more wire. But I see relatively little need for three phase in homes, other than as a means to have the main wires be 33% smaller.
| Plugs and sockets. To be honest, I can see problems with all of them. | You said: "Personally, I don't really like the BS1363." What don't you | like about them? They are painful if one is on the floor, with pins | up, and you tread on it with bare feet! They are quite large, but not
That's one reason.
| much more so than a Schuko. I like the internal fuse, essential on a | 30A ring circuits of course, but would have preferred to see different | sizes for different ratings; that would have required different plugs | of course, but would prevent fitting the wrong value fuse. I like the | shuttered outlets, and the shrouded pins. Not perfect, but not a bad
I do think shrouding or recessing, as well as shutters, are good.
| design. There was one strange problem with it; a one penny coin will | fit exactly between the three pins, and will touch all three. In the | days before the shrouded pins a practical joke was to place a coin in | this position, put the plug in a socket, and wait for somebody to | switch on. Most British sockets have a switch. The pins are nice | silid lumps of brass, expenive of course, and well capable of carrying | well over 100A, but they don't bend, have a large gontact area for a | good, low-resistance connection, and there's plenty of metal to allow | some to be removed at the base of the pins, to allow the plastic | shrouding; you couldn't do that with a NEMA, the metal just isn't thick | enough.
The joke done over here was to fold a piece of solder into the shape of a staple, with a hook on each end, and slip it over the plug. Then just leave the plug unplugged. I did try this a few times in college. What I discovered is that no one actually looks. They are so into having discovered the cause of the appliance not working, they just react by plugging it in. DON'T DO THIS AT HOME OR ANYWHERE ELSE. It really was stupid.
When I was in high school, someone folded up two pieces of foil from gum wrappers and fit each one carefully into the 120 volt outlet that was convenient for the movie projector in a class that was starting to fill up. When the teacher came in to show the movie, she noticed the projector had been unplugged, then noticed the wrappers in the socket. She remarked that this was a stupid trick and that someone could get hurt trying to play with the outlet. Then she proceeded to pull them both out at the same time. Fortunately, only her pride had any permanent injuries.
As a result of that, which I witnessed, I actually thought up my own design of outlet shutters. My design had a front face that was rotated around the ground pin. You plug in ground pin first and when it is in far enough, the ground pin would unlock the rotating face. Then you twist the plug some number of degrees and then it can be inserted the rest of the way. I was wishing the ground pin was in the middle of the outlet instead of offset.
Today I would have a circular metal shroud around the pins that is also the grounding connection, and have the shutters unlocked by the shroud, possibly by the rotating action to minimize the mechanics in the outlet that could break.
What I might do with the electrical system I've described so far is use a circular outlet/plug for the high voltage L-L, with 3 openings if three phase is available, arranged in a triangle, or just 2 of them if single phase is all that is available. A 2-pin plug would then fit a 3-opening outlet. The low voltage L-N would have a polarized pair of pins in a rectangular shroud.
Low voltage outlets would be limited to 10 amps. High voltage outlets would have versions for 16, 25, and 40 amps. I might make the 16 amp plug be compatible with the 25 amp socket by using a plug blade that is wider (not thinner or longer) so that the snugness is always there regardless of which plug type is used.
The low voltage 24 volts might even be DC, rectified and filtered from the 288 volts AC.
The tiers of current protection would be taken from every other value in a logarithmic decade scale: 10 16 25 40 64 100 160 250 400 640 1000, etc.
I'll try to make some drawings of my plug/socket configurations later.
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Y connected transformers are preferred on distribution systems. No problems with ferroresonance or backfeed.
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|
| |> Single phase is cheaper in rural areas. But maybe a usable compromise |> is to rule out ground return systems, which means you have to have at |> least 2 wires, and use 2 line wires out of the 3 for single phase. |> Then you can at least get the same ratio between L-N and L-L as you |> get with real three phase. But then, three phase is just one more |> wire, and allows the 3 wires to be a bit thinner to serve the same |> area. |> | | Y connected transformers are preferred on distribution systems. No problems | with ferroresonance or backfeed.
I would definitely have three phase transformer secondaries configured as Y or star. The primary would be delta. The loads would be L-L or L-L-L.
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