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Author Topic: Just a reminder to check the power at your distro as well as the wall.  (Read 21129 times)

Steve M Smith

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #60 on: January 30, 2014, 04:42:32 pm »

This diagram is not comprehensive.

Really?  Here is the diagram showing all of the UK domestic outlets:


The rating is determined by the fuse in the plug rather than having a different plug and socket set for each rating.  3A, 5A or 13A.

 

And you might find this one in bathrooms.  Transformer isolated for electric razors:


And very rarely, this one for electric clocks:


I have only ever seen one of these and that was in my grandfather's house about thirty years ago.


Steve.
« Last Edit: January 30, 2014, 04:47:03 pm by Steve M Smith »
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Rob Spence

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #61 on: January 30, 2014, 04:46:38 pm »

There has been a megavolt (+/- 500kV pole-ground) DC transmission line between The Dalles, Oregon and Sylmar, California since about 1970. http://en.wikipedia.org/wiki/Pacific_DC_Intertie


We have a million volt DC (+ & - 500kv) line here from Ayer to somewhere in Quebec. It has been in service for >20 years.

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TJ (Tom) Cornish

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #62 on: January 30, 2014, 04:48:58 pm »


Really?  Here is the diagram showing all of the UK domestic outlets:
The chart Jonathan posted covers FAR more than "domestic" receptacles.  For domestic receptacles in the same general usage case as what you show, we have basically two compatible versions of the same thing (clipped from the Wiki picture Jonathan used).  The others are special-purpose, and many are more analogous to your industrial Cee-forms.

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Jonathan Johnson

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #63 on: January 30, 2014, 05:34:48 pm »

The chart Jonathan posted covers FAR more than "domestic" receptacles.

Yes, there is a bewildering array of connector form factors in common use here in the United States, and that doesn't include the even larger array of now-obsolete connectors. For example, a receptacle with prongs in a crowsfoot layout (similar to NEMA 10-50 but the same size as NEMA 5-15) was listed for either 120V or 240V at 20 amps. These were typically used with large space heaters. There's an opportunity for disaster -- one could assume that a receptacle is 120V when it's really 240V. Thankfully, those obsolete plugs are no longer acceptable to the electrical codes, BUT they are still available for "repairs."

As a rule-of-thumb, the first number in a NEMA designation refers to a general physical size & prong placement, while the second number is the amperage rating.

In residential wiring, you will generally only see NEMA 5-15 receptacles (120V, 15A) for small appliances. NEMA 5-15 receptacles may be used on 20A circuits, though the connected load is not to exceed 15A -- which may be enforced by a circuit breaker in power strips. (It's rare to see a fused plug in the U.S.) That means that a multi-tap cord or adapter block without a breaker could potentially be overloaded, as could an ordinary extension cord, since most of the cords marketed to consumers are only 16 AWG (1.29mm). NEMA 5-15 receptacles may also appear in commercial installs.

NEMA 5-20 receptacles (120V 20A, compatible with NEMA 5-15 plugs) are usually only seen in commercial installations where there is potential for connected loads requiring more than 15 amps, though they may be installed in some residences. There is nothing to stop you from using a 16-gauge unfused extension cord on a 20A receptacle and overloading the cord.

NEMA 10-30, 10-50, 14-30, and 14-50 receptacles are usually only seen for clothes dryers (120/240V 30A) and kitchen ranges (120/240V 50A). As has been covered before, NEMA 10-30 and 10-50 implies that a bootleg ground will be present.

You might see a NEMA 6-15 or 6-20 receptacle (240V, 15A or 20A) used for a large window or through-wall air conditioner.

Other than that, the rest of those connectors will usually only be seen in commercial installations or large home workshops.

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To confuse the American consumer even more, for a given receptacle type (for example, NEMA 5-15) there are a number of different features: basic (read: cheap, <$1.00), "Pro" grade (slightly better than basic), "Spec" grade (meets military specifications), Isolated ground, hospital grade, tamper resistant, etc. And then there are Hubbell brand receptacles, which are overbuilt and nearly indestructible, but are also relatively expensive (~$10.00).
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Steve M Smith

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #64 on: January 30, 2014, 06:14:34 pm »

(It's rare to see a fused plug in the U.S.) That means that a multi-tap cord or adapter block without a breaker could potentially be overloaded, as could an ordinary extension cord

The advantage with having the fuse in the plug is that you can't overload anything (well, only until the fuse blows).

Our standard multi way extension lead/adaptor looks like this:


You could plug lots of these together to connect hundreds of appliances but they would all be drawing current from one plug.  And that plug will have a 13 amp fuse in it so the supply circuit cannot be overloaded (unless you replace the fuse with a piece of 1/4" rod!).


Steve.
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Stephen Swaffer

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #65 on: January 30, 2014, 08:39:20 pm »

Jonathan,

I knew how to wire the dryer-whether 3 wire or 4 wire without the manual; however, I was trying to use the project to teach a little to my 17 yr old son.  When he wasn't sure how to wire, my first thought was to hand him the manual  (I'd rather he learn how to figure out how to do something than just how to do it).  I glanced at it first, expecting to see "pic A, 3 wire hookup, pic b 4-wire".  Instead, there were 2 pages using oddball terms like "neutral ground".  Honestly, "white wire with ring terminal" would have been more descriptive and more easily understood by most people, and arguably no less accurate.  But then I suppose the author did not grow up building Heathkits!

I would like to see Mike's explanation, though.

Maybe those familiar with the DC distribution can answer a nagging question I have about it.  What technology is used for rectification and for converting back to AC?  Inverters are common these days, but high voltage is not solid state's strongpoint?
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Rob Spence

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #66 on: January 30, 2014, 08:45:35 pm »

Don't forget the (now) common L14-30 found on so many home portable generators.
Funny how the "L14-" is so different in size and shape than the "14-" connectors.

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Jonathan Johnson

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #67 on: January 30, 2014, 09:02:02 pm »

Maybe those familiar with the DC distribution can answer a nagging question I have about it.  What technology is used for rectification and for converting back to AC?  Inverters are common these days, but high voltage is not solid state's strongpoint?

I really don't know much about the technology. Conversion to DC is done at the Celilo Converter Station in The Dalles, Oregon, and conversion back to AC is done at the Sylmar Converter Station in Sylmar, California.

It seems to me that the conversion back to AC would be akin to a very, very big audio amplifier. Provide it high voltage, high current DC power, give it a 60Hz sine wave as "input" and output high voltage, high current AC power.
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TJ (Tom) Cornish

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #68 on: January 30, 2014, 09:04:25 pm »

I really don't know much about the technology. Conversion to DC is done at the Celilo Converter Station in The Dalles, Oregon, and conversion back to AC is done at the Sylmar Converter Station in Sylmar, California.

It seems to me that the conversion back to AC would be akin to a very, very big audio amplifier. Provide it high voltage, high current DC power, give it a 60Hz sine wave as "input" and output high voltage, high current AC power.
it used to be done in huge mercury rectifier tubes. There are You Tube videos that show these. I assume it is done via solid state tech now, but haven't seen anything about that.
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Jonathan Johnson

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #69 on: January 30, 2014, 09:07:17 pm »

it used to be done in huge mercury rectifier tubes. There are You Tube videos that show these. I assume it is done via solid state tech now, but haven't seen anything about that.
The inline links in my previous post link to relevant Wikipedia articles. They indicate that thyristors are now used in place of the mercury tubes.
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ProSoundWeb Community

Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #69 on: January 30, 2014, 09:07:17 pm »


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