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art(at)zemon.name
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 Posted: Fri May 13, 2016 12:52 am Post subject: Warm Extension Cord |
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Folks,
This isn't aero but it is electric so I figure someone here will have an opinion. When I am away from home, I use an extension cord to charge my electric car. Tonight, I noticed that the wire (not the connectors) was warm to the touch when I unplugged the car. The warmth surprised me. Here are the specs:
- 120V AC
- charger draws 12A
- 16 AWG conductors in the extension cord
- cord is 25 feet long
- cord was advertised as suitable for up to 13A
I'm inclined to replace the cord with one with 14 AWG conductors. Yes?
Thanks,
-- Art Z.
--
http://CheerfulCurmudgeon.com/"If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel
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racerjerry
Joined: 15 Dec 2009
Posts: 202
Location: Deer Park, NY
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| Posted: Fri May 13, 2016 2:42 am Post subject: Re: Warm Extension Cord |
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YES, replace with #14 or heavier. With any heating effects like this, make sure that you do NOT COIL up any loose ends of the extension cord, or the heat will be concentrated, causing the cord to melt and short out.
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bobnoffs
Joined: 04 Jul 2012
Posts: 132
Location: northern wi.
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| Posted: Fri May 13, 2016 3:21 am Post subject: Warm Extension Cord |
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that is at the max for the cord but not over the rating.a few years ago i made up some extension cords for 1500 watt heaters and used 12 ga. plenty of margin there. i guess i would feel better with 12ga. sounds like a one and done purchase.
funny the connectors aren't warm.
bob noffs
On Fri, May 13, 2016 at 3:49 AM, Art Zemon <art(at)zemon.name (art(at)zemon.name)> wrote:
| Quote: | Folks,
This isn't aero but it is electric so I figure someone here will have an opinion. When I am away from home, I use an extension cord to charge my electric car. Tonight, I noticed that the wire (not the connectors) was warm to the touch when I unplugged the car. The warmth surprised me. Here are the specs:
- 120V AC
- charger draws 12A
- 16 AWG conductors in the extension cord
- cord is 25 feet long
- cord was advertised as suitable for up to 13A
I'm inclined to replace the cord with one with 14 AWG conductors. Yes?
Thanks,
-- Art Z.
--
http://CheerfulCurmudgeon.com/"If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel
|
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rene(at)felker.com
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| Posted: Fri May 13, 2016 5:06 am Post subject: Warm Extension Cord |
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Was the wire coiled?
Rene'
801-721-6080
From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Art Zemon
Sent: Friday, May 13, 2016 2:50 AM
To: aeroelectric-list(at)matronics.com
Subject: Warm Extension Cord
Folks,
This isn't aero but it is electric so I figure someone here will have an opinion. When I am away from home, I use an extension cord to charge my electric car. Tonight, I noticed that the wire (not the connectors) was warm to the touch when I unplugged the car. The warmth surprised me. Here are the specs:
- 120V AC
- charger draws 12A
- 16 AWG conductors in the extension cord
- cord is 25 feet long
- cord was advertised as suitable for up to 13A
I'm inclined to replace the cord with one with 14 AWG conductors. Yes?
Thanks,
-- Art Z.
--
http://CheerfulCurmudgeon.com/
"If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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art(at)zemon.name
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| Posted: Fri May 13, 2016 6:11 am Post subject: Warm Extension Cord |
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No
-- Art Z.
Sent from my phone so please excuse typos and brevity. On May 13, 2016 8:30 AM, "Rene" <rene(at)felker.com (rene(at)felker.com)> wrote:
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ngeorge(at)continentalmot
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| Posted: Fri May 13, 2016 7:01 am Post subject: Warm Extension Cord |
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Even if the extension cord was coiled, paired conductors would effectively cancel the coil effect…
neal
No
-- Art Z.
Sent from my phone so please excuse typos and brevity.
On May 13, 2016 8:30 AM, "Rene" <rene(at)felker.com (rene(at)felker.com)> wrote:
Was the wire coiled?
Rene'
[url=tel:801-721-6080]801-721-6080[/url]
Folks,
This isn't aero but it is electric so I figure someone here will have an opinion. When I am away from home, I use an extension cord to charge my electric car. Tonight, I noticed that the wire (not the connectors) was warm to the touch when I unplugged the car. The warmth surprised me. Here are the specs:
- 120V AC
- charger draws 12A
- 16 AWG conductors in the extension cord
- cord is 25 feet long
- cord was advertised as suitable for up to 13A
I'm inclined to replace the cord with one with 14 AWG conductors. Yes?
Thanks,
-- Art Z.
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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rene(at)felker.com
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| Posted: Fri May 13, 2016 7:28 am Post subject: Warm Extension Cord |
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First hand experience……the heat build up can go out of control. Melted both the cable and a plastic spool it was on. Was on a camper and the wire did not feel “warm” normally but left it on the spool because it was a short distance…….spool and wire became one. Needed new spool and wire……..
Rene'
801-721-6080
From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Neal George
Sent: Friday, May 13, 2016 8:55 AM
To: aeroelectric-list(at)matronics.com
Subject: RE: Warm Extension Cord
Even if the extension cord was coiled, paired conductors would effectively cancel the coil effect…
neal
No
-- Art Z.
Sent from my phone so please excuse typos and brevity.
On May 13, 2016 8:30 AM, "Rene" <rene(at)felker.com (rene(at)felker.com)> wrote:
Was the wire coiled?
Rene'
[url=tel:801-721-6080]801-721-6080[/url]
Folks,
This isn't aero but it is electric so I figure someone here will have an opinion. When I am away from home, I use an extension cord to charge my electric car. Tonight, I noticed that the wire (not the connectors) was warm to the touch when I unplugged the car. The warmth surprised me. Here are the specs:
- 120V AC
- charger draws 12A
- 16 AWG conductors in the extension cord
- cord is 25 feet long
- cord was advertised as suitable for up to 13A
I'm inclined to replace the cord with one with 14 AWG conductors. Yes?
Thanks,
-- Art Z.
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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ARGOLDMAN(at)aol.com
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| Posted: Fri May 13, 2016 7:40 am Post subject: Warm Extension Cord |
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Greetings Art et al.
Advertised as????. Don't know if I would buy that.
Every wire has a certain resistance per foot (inch-nanometer) look at your aircraft tables. You seem to be overstressing the wire in that as electrons pass through any wire, the resistance to the flow not only creates voltage drop, but that resisted energy is expressed as heat. ( energy is not lost but is converted)
What you are experiencing is that heat, that you can feel, in this case. the extension chord wire is of too small a gauge or is too long for your application.
-- unless the heating is acceptable to the insulation.
I would get a better grade (gauge) of extension chord or shorten it as much as possible (resistance, remember is per foot etc). Don't coil the chord as the heat buildup may not have the ability to go into the atmosphere where it is harmless (that's where the heat of the engine goes... if it cant-- well.)
Rich
In a message dated 5/13/2016 8:29:27 A.M. Pacific Daylight Time, rene(at)felker.com writes:
| Quote: |
First hand experience……the heat build up can go out of control. Melted both the cable and a plastic spool it was on. Was on a camper and the wire did not feel “warm” normally but left it on the spool because it was a short distance…….spool and wire became one. Needed new spool and wire……..
Rene'
801-721-6080
From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Neal George
Sent: Friday, May 13, 2016 8:55 AM
To: aeroelectric-list(at)matronics.com
Subject: RE: AeroElectric-List: Warm Extension Cord
Even if the extension cord was coiled, paired conductors would effectively cancel the coil effect…
neal
No
-- Art Z.
Sent from my phone so please excuse typos and brevity.
On May 13, 2016 8:30 AM, "Rene" <rene(at)felker.com (rene(at)felker.com)> wrote:
Was the wire coiled?
Rene'
[url=tel:801-721-6080]801-721-6080[/url]
Folks,
This isn't aero but it is electric so I figure someone here will have an opinion. When I am away from home, I use an extension cord to charge my electric car. Tonight, I noticed that the wire (not the connectors) was warm to the touch when I unplugged the car. The warmth surprised me. Here are the specs:
- 120V AC
- charger draws 12A
- 16 AWG conductors in the extension cord
- cord is 25 feet long
- cord was advertised as suitable for up to 13A
I'm inclined to replace the cord with one with 14 AWG conductors. Yes?
Thanks,
-- Art Z.
|
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http://www.matronics.com/Navigator?AeroElectric-List |
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Robert Reed
Joined: 22 Oct 2009
Posts: 331
Location: Dallas/Ft.Worth
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| Posted: Fri May 13, 2016 7:47 am Post subject: Warm Extension Cord |
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My common sense rule says that if the cord gets warm in the intended use then a second rule becomes primary which considers the ability to monitor during use. If I can monitor during the entire time of usage then I can take action if it gets too hot. If the usage can not be monitored then it's damn cheap insurance and common sense to get a higher rated extension cord.
Bob Reed
Sent from my iPhone
On May 13, 2016, at 10:26 AM, Rene <rene(at)felker.com (rene(at)felker.com)> wrote:
| Quote: | <![endif]--> <![endif]-->
First hand experience……the heat build up can go out of control. Melted both the cable and a plastic spool it was on. Was on a camper and the wire did not feel “warm” normally but left it on the spool because it was a short distance…….spool and wire became one. Needed new spool and wire……..
Rene'
801-721-6080
From: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) [mailto:owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)] On Behalf Of Neal George
Sent: Friday, May 13, 2016 8:55 AM
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Subject: RE: Warm Extension Cord
Even if the extension cord was coiled, paired conductors would effectively cancel the coil effect…
neal
No
-- Art Z.
Sent from my phone so please excuse typos and brevity.
On May 13, 2016 8:30 AM, "Rene" <rene(at)felker.com (rene(at)felker.com)> wrote:
Was the wire coiled?
Rene'
[url=tel:801-721-6080]801-721-6080[/url]
Folks,
This isn't aero but it is electric so I figure someone here will have an opinion. When I am away from home, I use an extension cord to charge my electric car. Tonight, I noticed that the wire (not the connectors) was warm to the touch when I unplugged the car. The warmth surprised me. Here are the specs:
- 120V AC
- charger draws 12A
- 16 AWG conductors in the extension cord
- cord is 25 feet long
- cord was advertised as suitable for up to 13A
I'm inclined to replace the cord with one with 14 AWG conductors. Yes?
Thanks,
-- Art Z.
|
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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edpav8r(at)yahoo.com
Guest
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| Posted: Fri May 13, 2016 8:19 am Post subject: Warm Extension Cord |
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On May 13, 2016, at 7:55 AM, Neal George <ngeorge(at)continentalmotors.aero (ngeorge(at)continentalmotors.aero)> wrote:
| Quote: | <![endif]--> Clean false false false EN-US X-NONE X-NONE <![endif]--> <![endif]-->/* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri; mso-bidi-font-family:"Times New Roman";} <![endif]--> <![endif]--> <![endif]-->
Even if the extension cord was coiled, paired conductors would effectively cancel the coil effect…
neal
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Avoiding a coil in an extension cord isn't intended to avoid electromagnetic effects. The problem is that a coiled cord tends to concentrate heat much more than a cord that's stretched out straight.
Eric
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rv10pro(at)gmail.com
Guest
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| Posted: Fri May 13, 2016 8:25 am Post subject: Warm Extension Cord |
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Go for 12AWG stranded and mark the cost increase to common sense insurance.
John Cox On May 13, 2016 01:58, "Art Zemon" <art(at)zemon.name (art(at)zemon.name)> wrote: | Quote: | Folks,
This isn't aero but it is electric so I figure someone here will have an opinion. When I am away from home, I use an extension cord to charge my electric car. Tonight, I noticed that the wire (not the connectors) was warm to the touch when I unplugged the car. The warmth surprised me. Here are the specs:
- 120V AC
- charger draws 12A
- 16 AWG conductors in the extension cord
- cord is 25 feet long
- cord was advertised as suitable for up to 13A
I'm inclined to replace the cord with one with 14 AWG conductors. Yes?
Thanks,
-- Art Z.
--
http://CheerfulCurmudgeon.com/"If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel
|
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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lyleapgmc
Joined: 19 Feb 2014
Posts: 57
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| Posted: Fri May 13, 2016 9:05 am Post subject: Warm Extension Cord |
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I had the same experience as Rene' with a retractable extension cord. I was sure I had destroyed a brand new cord but fortunately the swollen insulation contracted.
I was given a long extension cord recently because it was "twisted." On inspection I determined that it has been over heating causing the insulation to swell and get loose letting the three wires shift inside the insulation, probably when the cord was wound around something for transport to the next task.
I was shopping for an extension cord and checking each cord's capacity. I was amazed when I noticed that all the cords claimed the same capacity regardless of the wire gauge. Marketing must have designed the labels and neither engineering nor risk management ever saw them.
On 5/13/2016 10:26 AM, Rene wrote:
| Quote: |
First hand experience……the heat build up can go out of control. Melted both the cable and a plastic spool it was on. Was on a camper and the wire did not feel “warm” normally but left it on the spool because it was a short distance…….spool and wire became one. Needed new spool and wire……..
Rene'
801-721-6080
From: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) [mailto:owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)] On Behalf Of Neal George
Sent: Friday, May 13, 2016 8:55 AM
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Subject: RE: Warm Extension Cord
Even if the extension cord was coiled, paired conductors would effectively cancel the coil effect…
neal
No
-- Art Z.
Sent from my phone so please excuse typos and brevity.
On May 13, 2016 8:30 AM, "Rene" <[url=mailto:rene(at)felker.com]rene(at)felker.com (rene(at)felker.com)[/url]> wrote:
Was the wire coiled?
Rene'
[url=tel:801-721-6080]801-721-6080[/url]
Folks,
This isn't aero but it is electric so I figure someone here will have an opinion. When I am away from home, I use an extension cord to charge my electric car. Tonight, I noticed that the wire (not the connectors) was warm to the touch when I unplugged the car. The warmth surprised me. Here are the specs:
- 120V AC
- charger draws 12A
- 16 AWG conductors in the extension cord
- cord is 25 feet long
- cord was advertised as suitable for up to 13A
I'm inclined to replace the cord with one with 14 AWG conductors. Yes?
Thanks,
-- Art Z.
|
On 5/13/2016 10:26 AM, Rene wrote:
| Quote: | <![endif]--> <![endif]-->
First hand experience……the heat build up can go out of control. Melted both the cable and a plastic spool it was on. Was on a camper and the wire did not feel “warm” normally but left it on the spool because it was a short distance…….spool and wire became one. Needed new spool and wire……..
Rene'
801-721-6080
From: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) [mailto:owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)] On Behalf Of Neal George
Sent: Friday, May 13, 2016 8:55 AM
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Subject: RE: Warm Extension Cord
Even if the extension cord was coiled, paired conductors would effectively cancel the coil effect…
neal
No
-- Art Z.
Sent from my phone so please excuse typos and brevity.
On May 13, 2016 8:30 AM, "Rene" <[url=mailto:rene(at)felker.com]rene(at)felker.com (rene(at)felker.com)[/url]> wrote:
Was the wire coiled?
Rene'
[url=tel:801-721-6080]801-721-6080[/url]
Folks,
This isn't aero but it is electric so I figure someone here will have an opinion. When I am away from home, I use an extension cord to charge my electric car. Tonight, I noticed that the wire (not the connectors) was warm to the touch when I unplugged the car. The warmth surprised me. Here are the specs:
- 120V AC
- charger draws 12A
- 16 AWG conductors in the extension cord
- cord is 25 feet long
- cord was advertised as suitable for up to 13A
I'm inclined to replace the cord with one with 14 AWG conductors. Yes?
Thanks,
-- Art Z.
|
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ceengland7(at)gmail.com
Guest
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| Posted: Fri May 13, 2016 9:54 am Post subject: Warm Extension Cord |
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Hi Art,
I'd assume that if you went to the trouble to buy or build an electric car, you have at least some focus on efficiency. So here's something to consider. According to one convenient online calculator,
http://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=13.17&voltage=120&phase=ac&noofconductor=1&distance=25&distanceunit=feet&eres=12&x=47&y=17
16 awg 25 ft 120vac 12A will have ~2.4 volts of drop at the load. That means you're using 2.4*12=28.8 watts to heat the wire (likely a bit more than that). So, roughly the equivalent of plugging in a small soldering iron & leaving it running while the car charges.
Same load with 12 awg: 0.95v drop * 12 = 11.4 watts lost to the wire.
To keep it Aeroelectric related, 'the book' has formulas to do the calcs.
Charlie
On 5/13/2016 6:20 AM, bob noffs wrote:
| Quote: | that is at the max for the cord but not over the rating.a few years ago i made up some extension cords for 1500 watt heaters and used 12 ga. plenty of margin there. i guess i would feel better with 12ga. sounds like a one and done purchase.
funny the connectors aren't warm.
bob noffs
On Fri, May 13, 2016 at 3:49 AM, Art Zemon <art(at)zemon.name (art(at)zemon.name)> wrote:
| Quote: | Folks,
This isn't aero but it is electric so I figure someone here will have an opinion. When I am away from home, I use an extension cord to charge my electric car. Tonight, I noticed that the wire (not the connectors) was warm to the touch when I unplugged the car. The warmth surprised me. Here are the specs:
- 120V AC
- charger draws 12A
- 16 AWG conductors in the extension cord
- cord is 25 feet long
- cord was advertised as suitable for up to 13A
I'm inclined to replace the cord with one with 14 AWG conductors. Yes?
Thanks,
-- Art Z.
--
http://CheerfulCurmudgeon.com/ "If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel
|
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egilroy(at)gmail.com
Guest
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| Posted: Fri May 13, 2016 11:41 am Post subject: Warm Extension Cord |
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I used the following table from the J1772 specifications to build my homemade extension cord for my electric car:
Electrical
• Level 1: 14 AWG - 16A
• Level 2: 10 AWG - 30A
• Level 2: 8 AWG - 31 to 74A
• Level 2: 6 AWG - 75 to 99A
I used 10 gauge, it is always just warm to the touch after a few hours of charging, but not anything I would call hot. I pull 12A on high and 8A on low at 120V.
On Fri, May 13, 2016 at 1:55 PM, Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)> wrote:
| Quote: | Hi Art,
I'd assume that if you went to the trouble to buy or build an electric car, you have at least some focus on efficiency. So here's something to consider. According to one convenient online calculator,
http://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=13.17&voltage=120&phase=ac&noofconductor=1&distance=25&distanceunit=feet&eres=12&x=47&y=17
16 awg 25 ft 120vac 12A will have ~2.4 volts of drop at the load. That means you're using 2.4*12=28.8 watts to heat the wire (likely a bit more than that). So, roughly the equivalent of plugging in a small soldering iron & leaving it running while the car charges.
Same load with 12 awg: 0.95v drop * 12 = 11.4 watts lost to the wire.
To keep it Aeroelectric related, 'the book' has formulas to do the calcs.
Charlie
On 5/13/2016 6:20 AM, bob noffs wrote:
| Quote: | that is at the max for the cord but not over the rating.a few years ago i made up some extension cords for 1500 watt heaters and used 12 ga. plenty of margin there. i guess i would feel better with 12ga. sounds like a one and done purchase.
funny the connectors aren't warm.
bob noffs
On Fri, May 13, 2016 at 3:49 AM, Art Zemon <art(at)zemon.name (art(at)zemon.name)> wrote:
| Quote: | Folks,
This isn't aero but it is electric so I figure someone here will have an opinion. When I am away from home, I use an extension cord to charge my electric car. Tonight, I noticed that the wire (not the connectors) was warm to the touch when I unplugged the car. The warmth surprised me. Here are the specs:
- 120V AC
- charger draws 12A
- 16 AWG conductors in the extension cord
- cord is 25 feet long
- cord was advertised as suitable for up to 13A
I'm inclined to replace the cord with one with 14 AWG conductors. Yes?
Thanks,
-- Art Z.
--
http://CheerfulCurmudgeon.com/ "If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Fri May 13, 2016 1:19 pm Post subject: Warm Extension Cord |
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At 09:55 AM 5/13/2016, you wrote:
| Quote: | | Even if the extension cord was coiled, paired conductors would effectively cancel the coil effect |
You're thinking of magnetic fields around the pair, not
temperature rise. A couple years ago, I was working a
summer fun-fair in a small town south of Wichita with
my son who has a shaved ice business. The curbside
outlet that supplied power to the trailer was only
about 20' away . . . so I only un-rolled about 30'
of 12AWG cord off a stowage reel and hooked up the
trailer. The total load for the trailer was 16A
with the A/C running. Normally, the 12AWG would get
just warm to the touch at that load.
A few hours into the event, the folks working the
booth next to us raised the red flag on smoke rising
from the cord reel. I powered down and unrolled
the cord. The deepest 25 feet of cordage was badly
melted and starting to char in some areas.
The problem was obvious . . . and SHOULD have
been considered by a veteran wire-stringer . . .
but we trashed part of the cord that was MOST
insulated from outside air. Cut it off, replaced
the connector and was back in business about 15
minutes later . . . with remaining cord all laid out
on the ground so it could cool off.
Remember, 20 amps won't burn a 22AWG copper wire
http://tinyurl.com/6qr72fr
in fact, it doesn't even put Tefzel insulation
at risk . . . in the open air. But bundle it up
in any manner that reduces ability to reject heat
and . . .
[img]cid:.0[/img]
Here's a bundle of wires that are insulated with the slicone/
fiberglas sleeving. The bundle has two 10AWG conductors that MIGHT
get loaded to 60A under some conditions. Out in the open
air, no sweat . . . or should I say no burn?
I set up a lab test for the boss to deduce the INCREASE in temperature
rise for having been bundled.
[img]cid:.1[/img]
Wire under the sleeve was 80 to 115C
hotter than the single strand in open air.
It was hot enough on the outside of the
fiberglas to discolor nylon tie-wraps
[img]cid:.2[/img]
and the Tefzel insulation began to loose
its bond at the edges of the wrap
[img]cid:.3[/img]
The copper inside was un-affected. As it turns
out, nobody ever installed ALL of the accessories
that would have put the airplane at risk. But it
was more trouble on the drawings to change the
optional equipment list. Only one drawing had
to be changed to upsize the wire. So a mandatory
service bulletin was issued against all aircraft
with that installation and the factory pushed the
upgrade costs off onto the field . . . to fix an
non-issue. Sigh . . .
Anyhow, if you can hold your 14AWG cord in
your hand . . . AND no part of it is deprived
of cooling air . . . then the wire is not
at risk. The weakest link in that system is
the connectors. I've seen several UL approved
15A rated wall outlets fail at 12A loads.
Two in a row in a house I was living in, one
in a house we investigated for a fire of
electrical origins . . . right under where
a 115v window a/c had been installed.
The advice for upsizing is well made . . . to
which would suggest more robust connectors
perhaps of the twist-lock variety.
Bob . . .
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neal.george(at)gmail.com
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| Posted: Fri May 13, 2016 7:51 pm Post subject: Warm Extension Cord |
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Yeah, short, incomplete response. I know better. Mea Culpa. (did I say that correctly?)
I assumed the resistive thermal rise and lack of cooling from a pile of cable were a given.
I have foggy memories of stories from an ancient electrical instructor, possibly unfounded, of inexperienced electricians separating A/C phases in conduit resulting in catastrophic thermal failure...
I'm sorry sir, I'll be quiet. 
NealSent from my iPhone
On May 13, 2016, at 4:17 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | At 09:55 AM 5/13/2016, you wrote:
| Quote: | | Even if the extension cord was coiled, paired conductors would effectively cancel the coil effect… |
You're thinking of magnetic fields around the pair, not temperature rise. Bob . . . |
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nuckolls.bob(at)aeroelect
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| Posted: Sun May 15, 2016 9:46 am Post subject: Warm Extension Cord |
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At 10:50 PM 5/13/2016, you wrote:
| Quote: | Yeah, short, incomplete response. I know better. Mea Culpa. (did I say that correctly?)
I assumed the resistive thermal rise and lack of cooling from a pile of cable were a given.
I have foggy memories of stories from an ancient electrical instructor, possibly unfounded, of inexperienced electricians separating A/C phases in conduit resulting in catastrophic thermal failure... |
Interesting . . . I'll have to ponder that a bit.
I too have an anecdotal recollection of noises
emanating from overhead conduits when some high-
inrush machine was turned on back in Electro-Mech's
shops.
After mentioning it to one of the grey-beard
electricians who came out to add some outlets,
he explained that when the installer pulls three
separate conductors into a conduit, the electromagnetic
repulsion between adjacent conductors is free to
initiate some degree of 'thrashing about' within
the conduit.
He allowed as how it didn't make much difference
in a factory environment . . . but when his
company ran heavy duty wiring over, say, the
suspended ceilings of an office, their practice
was to pull in twisted trios so that the
conductors were not so free to move away
from each other.
Years ago I had a video taken of a large
loop of wire laying on a floor that was suddenly
energized with a very high current. The
loop of wire writhed on the floor like
a giant snake.
There's a youtube video that demonstrates
the potential for attraction/repulsion
forces between two conductors.
https://youtu.be/GW7PvSR9VUo
Of course, this is a purely mechanical
consequence of magnetic forces. The heating effect
you cited is another matter. The only thing I
can think of right now is that large AC
currents not flowing in equal-opposite,
close-proximity would induce eddy-currents
in the surrounding conduit which can only raise
the temperature of the conduit.
That would be an interesting physics lab
experiment. Thanks for posing the hypothesis!
Bob . . .
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user9253
Joined: 28 Mar 2008
Posts: 1935
Location: Riley TWP Michigan
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| Posted: Sun May 15, 2016 3:24 pm Post subject: Re: Warm Extension Cord |
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Years ago I took a college course on the National Electrical Code. The instructor was an electrical inspector. He told about inspecting the electrical installation in a commercial building. The installer had done a very neat job with all of the white neutral wires in one conduit and all of the hot wires in another conduit coming from the electrical service panel. After the building was occupied, the tenant called the inspector complaining about hot conduits. The installer had to come back and rewire the panel with the hot and neutral wires from each circuit sharing the same conduit.
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nuckolls.bob(at)aeroelect
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| Posted: Mon May 16, 2016 5:35 am Post subject: Warm Extension Cord |
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At 06:24 PM 5/15/2016, you wrote:
| Quote: | --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com>
Years ago I took a college course on the National Electrical Code. The instructor was an electrical inspector. He told about inspecting the electrical installation in a commercial building. The installer had done a very neat job with all of the white neutral wires in one conduit and all of the hot wires in another conduit coming from the electrical service panel. After the building was occupied, the tenant called the inspector complaining about hot conduits. The installer had to come back and rewire the panel with the hot and neutral wires from each circuit sharing the same conduit.= |
Makes sense. If you imagine just a short piece
of conduit . . . say 1" long with a number of
wires through it. The conduit couples to the
wires just like a torroid transformer core
except the steel in the conduit was never
intended for transformer duties . . . high
eddy-current losses. While each conductor might not
carry a lot of current (keeping I(squared)R
losses low) the sum of many conductors could
be putting tens of ampere-turns of energy
into the 'core' which can do nothing with it
but get warmer. Keeping the outbound and return
electron paths paired through the very long
"core" is the secret to getting more power
to the other end and keeping the "core"
cooler.
Bob . . .
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art(at)zemon.name
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| Posted: Wed May 18, 2016 1:44 pm Post subject: Warm Extension Cord |
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Whoa! I posted a question, went away for a few days of R&R, and I come back to a torrent of conversation!
I guess I'll be reading for awhile.
-- Art Z.
--
http://CheerfulCurmudgeon.com/"If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel
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