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Author Topic: Power Outlets Worldwide  (Read 2208 times)

Jonathan Johnson

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Power Outlets Worldwide
« on: December 23, 2013, 03:28:22 pm »

We usually just turn up and have a choice of three industrial connectors to plug into with no problrms.  The US appears to have an ever increasing* inventory of outlets and wiring arrangements, grounding methods, etc.

It's partly due to the fact that we have multiple voltage standards: 120V single phase, 240V single phase, 120/240V single phase, 120/240/208 volt wild-leg single/three phase delta, 120/208V three-phase wye, 277/480V three-phase wye, etc.

Add to that the fact that there are several different amperages (15A, 20A, 30A, 50A, etc.) in common use, and the array of cord-and-plug configurations becomes bewildering.

Since previous standards allowed for bootleg ground (grounding through the neutral wire) in some appliances, typically kitchen ranges and clothes dryers, there are a few extras out there that are now considered obsolete.

About the only interchangeability is that 120V 20A receptacles allow you to connect a 120V 15A plug, and 240V 20A receptacles allow you to connect a 240V 15A plug. Common household wiring uses 14- and 12-gauge (American Wire Gauge) wiring, which means that both 15A and 20A circuits are available.

Could the United States switch to something more universal? Not easily. There is too much installed base to go changing things up. Look at how hard it's proving to switch the Internet from IPv4 to IPv6. Sure, we could decide to go to just 12-gauge wiring for household circuits and dump 15A circuits in new construction, but consumers would balk at the increased cost, and electricians would balk at the increased difficulty of handling heavier wire. It might also necessitate fused plugs on every cord, which so far only exist in holiday light strings.
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Chris Hindle

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Re: Power Outlets Worldwide
« Reply #1 on: December 23, 2013, 04:08:20 pm »

It might also necessitate fused plugs on every cord, which so far only exist in holiday light strings.

And Air Conditioners.
Replaces one at the house last summer, and replaced one at the office 3-4 years ago. Both have plug mounted breakers.
I must say, it's not a bad idea, just makes for a bloody big 90 plug sticking out of the wall....

(edit: cunt spel)
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Steve M Smith

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Re: Power Outlets Worldwide
« Reply #2 on: December 23, 2013, 04:23:25 pm »

Since previous standards allowed for bootleg ground

I was going to ask about that.  Is or was bootleg grounding ever an acceptable method of providing a ground?  Over here (UK) no one would ever think about connecting the ground pin to neutral in order to provide a ground.  I have seen neutral referred to as the 'ground conductor' here which I suppose would naturally lead you to think it was interchangeable with a proper ground.

It's partly due to the fact that we have multiple voltage standards: 120V single phase, 240V single phase, 120/240V single phase, 120/240/208 volt wild-leg single/three phase delta, 120/208V three-phase wye, 277/480V three-phase wye, etc.

We just have the one system.  415v three phase.  All three phases go to industrial and commercial premises and a single phase and neutral go to domestic properties to provide 240v.

About the only interchangeability is that 120V 20A receptacles allow you to connect a 120V 15A plug, and 240V 20A receptacles allow you to connect a 240V 15A plug. Common household wiring uses 14- and 12-gauge (American Wire Gauge) wiring, which means that both 15A and 20A circuits are available.

I was wondering how many domestic outlets the US have approved for use.  We just have one.  The 13 amp socket.  Before the 1960s, we had three sockets.  3 amp (not common) 5 amp and 15 amp.  These were fused at the fuse box.  Our current system uses a 13 amp rated plug and socket with a fuse in the plug selected according to the appliance.  Usually 3, 5 or 13 amps.

For industrial power we just have a handful of connectors in single and three phase options.


Steve.
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Tim McCulloch

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Re: Power Outlets Worldwide
« Reply #3 on: December 23, 2013, 05:09:31 pm »

The Code definition of what we call "neutral" is "Grounded, current-carrying conductor".  I suspect that the "ed" is left off in typographical error in some posts.
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Jonathan Johnson

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Re: Power Outlets Worldwide
« Reply #4 on: December 24, 2013, 12:20:51 am »

The Code definition of what we call "neutral" is "Grounded, current-carrying conductor".  I suspect that the "ed" is left off in typographical error in some posts.

And what we in the U.S. call the "ground wire" (or just "ground") -- what you in Europe call "earth" -- is really the "Equipment Grounding Conductor". When it comes to anything regarding codes, insurance, or any legal document, semantics are VERY important.

The term "neutral" is really a misnomer, as it's not truly neutral since it carries current. To use a single-word term, it should be referred to as "common" as it is a zero-voltage potential reference point for both poles of the 120/240V split, the grounding wire, and in a three-phase wye-connected system, to one leg of each of the phases (at the center of the wye).
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Steve M Smith

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Re: Power Outlets Worldwide
« Reply #5 on: December 24, 2013, 02:52:05 am »

The Code definition of what we call "neutral" is "Grounded, current-carrying conductor".  I suspect that the "ed" is left off in typographical error in some posts.

Even with it's correct (in the US) title with the word grounded in it, there is a likelihood of people thinking it is ok to use it as a ground connection. Evidence of this is the common occurrence of bootleg grounding being mentioned here.  Something I had never heard of until I joined this forum.

With our terms of live, neutral and earth, no one confuses neutral with earth - in fact most people probably do not realise that they are connected together anywhere.


Steve.
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Mike Sokol

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Re: Power Outlets Worldwide
« Reply #6 on: December 24, 2013, 03:10:59 am »

Even with it's correct (in the US) title with the word grounded in it, there is a likelihood of people thinking it is ok to use it as a ground connection. Evidence of this is the common occurrence of bootleg grounding being mentioned here.  Something I had never heard of until I joined this forum.

With our terms of live, neutral and earth, no one confuses neutral with earth - in fact most people probably do not realize that they are connected together anywhere.

Steve.

The only code-legal bootleg grounds were (and still are) for our split-phase 120/240-volt 30 and 50 amp services for electric dryers and stoves. While new installations require a 4-wire hookup (L1, L2, N, G) there were probably millions of installations with a 3-wire hookup that bonded the appliance chassis directly to the neutral conductor, and which are still code-legal since they're grandfathered in. When you purchase a new stove there will be a little "bonding" screw between the neutral terminal and chassis which you're supposed to remove if you buy the 4-wire power cord rather than the 3-wire "bootleg ground" power cord.

The US national electrical code (NFPA 70E) also allowed (and I think still allows in some industrial circumstances) for a metal conduit to function as the safety ground. For sound systems this is a mess since this conduit can be bonded to building steel in multiple places, almost assuring a ground loop differential voltage with the resultant ground loop current and speaker hum.

A receptacle "bootleg ground" was never officially allowed by the national code, but was sometimes (often?) done by inspectors and electricians in the 70's as a cheap way to convert old 2-wire power (hot and neutral) circuits to a 3-wire "grounded" receptacle (hot, neutral and ground). But combining a bootleg ground with a swapped neutral and hot creates what I've named a Reverse Polarity Bootleg Ground (RPBG) which can be really difficult to find as I've noted in other postings. Here's an article I wrote on the subject for Electrical Construction and Maintenance Magazine at http://ecmweb.com/contractor/failures-outlet-testing-exposed where I go into detail about why standard outlet testing methods won't find an RPBG. As you can see from the sidebar in the article, this can also cause dangerous fault currents to flow between pro-sound gear components interconnected to multiple power outlets.
« Last Edit: December 24, 2013, 08:00:50 am by Mike Sokol »
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Stephen Swaffer

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Re: Power Outlets Worldwide
« Reply #7 on: December 24, 2013, 09:43:26 am »


I was wondering how many domestic outlets the US have approved for use.  We just have one.  The 13 amp socket.  Before the 1960s, we had three sockets.  3 amp (not common) 5 amp and 15 amp.  These were fused at the fuse box.  Our current system uses a 13 amp rated plug and socket with a fuse in the plug selected according to the appliance.  Usually 3, 5 or 13 amps.


Typically, we just use the 15A/20A receptacles which are interchangeable unless you have a 20 plug-pretty rare.  The other receptacles are for ranges (50A/240V) dryers (30 A/ 240V) and an occasional welder (50A/240V-ground no neutral) then we have 2 4 wire twistlocks for generators a 20A and a 30A.  But the load served by those extras would not be able to be served by the 13 A receptacle you use.

Mike, have you considered using a non contact voltage detector for finding RPBGs?  I use a Fluke that gives me a blue light when some distance away then turns red when in close proximity to a "hot" wire to differentiate between hot and neutral on knob and tube systems when I have to deal with them.  Perhaps a plug with two individual wires coming out wire nutted/taped for safety along with a detector would be any easy way to ID a RPBG?
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Steve Swaffer

Geoff Doane

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Re: Power Outlets Worldwide
« Reply #8 on: December 24, 2013, 10:22:18 am »


I was wondering how many domestic outlets the US have approved for use.  We just have one.  The 13 amp socket. 


What do you do for electric stoves, ranges, or whatever they're called there?  Or does everybody use gas?  Or coal  :D ?

Until the NEMA 14-50 came into wide use in my part of Canada (sometime in the '80s?), kitchen stoves were tied into a pigtail coming out of the wall.  If you moved house, and were taking the stove with you, you disconnected and tied it in yourself.  It was good practice for a future career in Rock 'n' Roll.  ;)

GTD
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Steve M Smith

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Re: Power Outlets Worldwide
« Reply #9 on: December 24, 2013, 10:46:47 am »

What do you do for electric stoves, ranges, or whatever they're called there?  Or does everybody use gas?  Or coal

Electric ovens are permanently wired in via isolating switches.  As are permanently installed room heaters and hot water heaters.

I think there is an equal divide between electric and gas for cooking in the UK.

Until the NEMA 14-50 came into wide use in my part of Canada (sometime in the '80s?), kitchen stoves were tied into a pigtail coming out of the wall.  If you moved house, and were taking the stove with you, you disconnected and tied it in yourself.

If you move house here and take your electric oven with you, a qualified electrician is supposed to do any dis-connecting and re-connecting... This hardly ever happens!


Steve,
« Last Edit: December 24, 2013, 10:50:05 am by Steve M Smith »
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