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Author Topic: Cheap extension cords  (Read 1997 times)

Lyle Williams

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Re: Cheap extension cords
« Reply #10 on: July 29, 2017, 08:51:20 pm »

The standard of safety you walk past is the standard of safety you get.
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Jonathan Johnson

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Re: Cheap extension cords
« Reply #11 on: July 31, 2017, 12:55:49 pm »

In this situation it looks like you would physically be able to touch both the live and neutral connector on that plug accidentally? That itself should be a "life threatening situation".

Welcome to the United States, where every plug is designed to expose live conductors when only partially inserted.

Why can't some portion (5 mm maybe) of the prongs closest to the plug body be insulated, like they are in Europe? Maybe because the prongs are already as thin as they can be without overloading them or weakening them, so there's no way to effectively insulate them without seriously derating the plug. Nothing like living on the edge.
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Jonathan Johnson

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Re: Cheap extension cords
« Reply #12 on: July 31, 2017, 12:59:17 pm »

Many years ago I had a problem with an SMT machine that would randomly crash.  One fine day I happened to touch both the machine and the adjacent conveyor and felt a tingle.  Grabbed a meter and there was nearly 50VAC between the chassis'.  Enough that when the metal conveyors touched from vibrations that the brief spike cause something in the SMT machine to lose it's mind.  I traced it down to someone having pulled the conveyor's 110 service out of the dedicated box on the floor and inserted a cheap plastic power strip so they could also plug in a fan.  And the power strip had the ground prong broken out.
I don't know if what felt like a tingle to me touching the anodized conveyor rails (which provides some degree of insulation) might have done to someone with maybe a pacemaker getting the full effect of it.  Obviously I fixed it right away and explained to the operators and folks nearby that it was causing the machine to crash.  Since nobody had been "hurt" trying to explain the possibility to them would have gone nowhere.

This story brings up two questions in my mind:

  • Why is there stray voltage on the equipment? (primary failure)
  • Why hasn't the stray voltage been shunted to ground? (secondary failure)

Your story indicates that the secondary failure was resolved, but not the primary. Fixing the ground might protect personnel from shock, but it doesn't resolve the initial problem of a possible short to ground. If it's a high-resistance short, it might not draw enough current to trip a breaker, but it could cause heating of components potentially resulting in fire or other damage.

When a person receives a shock other than directly touching a live conductor, there are almost always two failures: a primary failure of the electrical insulation, and a secondary failure of the grounding system.
« Last Edit: July 31, 2017, 01:01:59 pm by Jonathan Johnson »
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David Buckley

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Re: Cheap extension cords
« Reply #13 on: July 31, 2017, 05:20:25 pm »

Why can't some portion (5 mm maybe) of the prongs closest to the plug body be insulated, like they are in Europe? Maybe because the prongs are already as thin as they can be without overloading them or weakening them, so there's no way to effectively insulate them without seriously derating the plug.

That's the New Zealand problem.  We have the insulated bit round the pins so you cant touch them, but you only have to look at a plug askance and the pins will bend. 
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Bill Koonce

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Re: Cheap extension cords
« Reply #14 on: July 31, 2017, 08:07:08 pm »

Seems like the time is past due to do a major refresh, and approve something better than what is still Harvey Hubbell's 1904 invention with few changes. If we could agree on the IEC 60320 standard for the other end of AC cords worldwide, why can't we do the same thing at the wall outlet? I've seen C13/C14 connectors used on power strips in data centers; why not make them legal for home use?
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Caleb Dueck

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Re: Cheap extension cords
« Reply #15 on: August 01, 2017, 06:30:31 am »

Why not Powercon?

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Lyle Williams

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Re: Cheap extension cords
« Reply #16 on: August 01, 2017, 12:01:00 pm »

Why not Powercon?

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Because powercon suck in nearly every regard except they don't fall out.

They are not rated for live disconnection.

Residential connectors need to pull out of the wall and disconnect when yanked/tripped over.  Pulling the wallplate out of the wall or tearing the wires out of the back of the connector is not ok.
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Stephen Swaffer

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Re: Cheap extension cords
« Reply #17 on: August 01, 2017, 12:44:27 pm »

Seems like the time is past due to do a major refresh, and approve something better than what is still Harvey Hubbell's 1904 invention with few changes. If we could agree on the IEC 60320 standard for the other end of AC cords worldwide, why can't we do the same thing at the wall outlet? I've seen C13/C14 connectors used on power strips in data centers; why not make them legal for home use?

Economics is the hold up, not legality.  I can't find anything in the code to prevent you from using any configuration you want.  Code requires single phase 125 volt 15 or 20 A receptacles.  Interestingly,  it doesn't specify a configuration-it does require a unique configuration in an occupancy for each voltage/phase configuration.  It does require tamper resistant-I doubt their are any TR listed C13/14 receptacles on the market.

Who is going to lead the change?  Any new home is still going to have to have 5-15s to be acceptable to the consumer.  Any combo receptacle is going to break the bank as far as quoting a job.  Then, if you produce an appliance with C13/14 connections, how many homes will it work in?
« Last Edit: August 01, 2017, 04:19:06 pm by Stephen Swaffer »
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brian maddox

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Re: Cheap extension cords
« Reply #18 on: August 01, 2017, 01:07:48 pm »

Economics is the hold up, not legality.  I can't find anything in the code to prevent you from using any configuration you want.  Code requires single phase 125 volt 15 or 20 A receptacles.  Interstingly,  it doesn't specify a configuration-it does require a unique configuration in an occupancy for each voltage/phase configuration.  It does require tamper resistant-I doubt their are any TR listed C13/14 receptacles on the market.

Who is going to lead the change?  Any new home is still going to have to have 5-15s to be acceptable to the consumer.  Any combo receptacle is going to break the bank as far as quoting a job.  Then, if you produce an appliance with C13/14 connections, how many homes will it work in?

this.  obviously...

I do think that having insulation on the lower part of the blades of a Male Edison Connector may have some validity and i could see that being put into place with regulations and eventually becoming the norm.  Especially on fixed power cords for an appliance where the load is a known quantity so it isn't necessary to have enough blade surface to support 15 amps of current.
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TJ (Tom) Cornish

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Re: Cheap extension cords
« Reply #19 on: August 01, 2017, 01:51:29 pm »

Shock issues by touching 5-15p blades aren't going to be a driver of changing electrical distribution - that liability is a very known quantity with way too much installed base.

The things that may change distribution methods over time (decades) are those that have economic or practical benefit.  Electric vehicles, solar roofs, LED lighting, and USB/other low power devices are examples. 

Currently, lighting circuits are based around incandescent lamps, and the electrical code sizes breakers and wiring to the potential load on a circuit, not the actual load.  In other words, it doesn't matter if you have an 8 watt LED bulb screwed into a fixture, the fact that the fixture can hypothetically handle a 150w incandescent lamp requires the infrastructure to support the full 150w loads.  As this turns over - in the interim GU10/GU24 or the semi-proprietary orange connectors found in LED recessed lighting, the size of wire necessary for the much-reduced lighting load can get smaller and therefore cheaper.  5 amp breakers feeding LED lighting loads are more than sufficient, and this reduced wire gauge and reduced potential energy for fire or arc-flash are secondary safety benefits.  In the longer term, low voltage may replace line voltage, reducing shock potential as well.

There are already receptacles with USB charging ports on them.  Europe has mandated that cell phones use a common USB plug for powering to reduce the number of old adapters in landfills.  Right now the USB specification itself is in flux so probably not a good long-term bet (ask me how many adapters I carry for my USB-C-based MacBook Pro), but this is a step in the right direction. 

Things like heaters, power tools, curling irons, and other high-drain devices will probably never allow us to fully move over to lower voltage or power wiring, but we're moving the needle. 

Electric vehicles and the charging infrastructure to make them work will be a big deal, and if distributed solar to power it all becomes a reality, interesting things will happen.
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