Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
Author: Subject: Burnt hotplate cord
Murexide
Harmless
*




Posts: 40
Registered: 1-12-2018
Member Is Offline


[*] posted on 8-10-2019 at 00:37
Burnt hotplate cord


As many amateur chemists have experienced, I had the unfortunate experience of allowing my hotplate cord to contact the hotplate for a few seconds. After realising, I immedaitely removed the cord. Around 0.5 mm of the plastic covering to the cord was burnt off, but none of the contents were visible. I removed the small plastic deposit on the hotplate and wrapped the exposed cord with electrical wire.

The hotplate should now be fully functional and hopefully safe. Are there any obvious unforseen dangers that I am missing?
View user's profile View All Posts By User
markx
International Hazard
*****




Posts: 593
Registered: 7-8-2003
Location: Northern kingdom
Member Is Offline

Mood: Very Jolly

[*] posted on 8-10-2019 at 02:06


Change the cord out for a new one that is undamaged. The conduits might not be visible, but the internal insulation might have become damaged by the heat and may cause a short after being bent or wrapped in the wrong way.



Exact science is a figment of imagination.......
View user's profile View All Posts By User
Murexide
Harmless
*




Posts: 40
Registered: 1-12-2018
Member Is Offline


[*] posted on 8-10-2019 at 02:21


The cord is attached internally and leads directly into the hotplate. Is it still possible to replace such a cord?
View user's profile View All Posts By User
Ubya
International Hazard
*****




Posts: 902
Registered: 23-11-2017
Location: Rome-Italy
Member Is Offline

Mood: I'm a maddo scientisto!!!

[*] posted on 8-10-2019 at 02:49


Quote: Originally posted by Murexide  
The cord is attached internally and leads directly into the hotplate. Is it still possible to replace such a cord?

by opening the case of your hotplate, yes





---------------------------------------------------------------------
feel free to correct my grammar, or any mistakes i make
---------------------------------------------------------------------
View user's profile View All Posts By User
wg48temp9
National Hazard
****




Posts: 324
Registered: 30-12-2018
Member Is Offline


[*] posted on 8-10-2019 at 03:32


Quote: Originally posted by Ubya  
Quote: Originally posted by Murexide  
The cord is attached internally and leads directly into the hotplate. Is it still possible to replace such a cord?

by opening the case of your hotplate, yes


and there is a good chance the power connections are push on spade connectors so you could replace the lead with one salvaged from some other equipment but make certain the conductors are the same size/large or the salvaged equipment has the same or greater power rating.

Alternatively just cut the lead at the damage point and put a plug on it and if needed use an extension cord.






i am wg48 but not on my usual pc hence the temp handle.

Thank goodness for Fleming and the fungi.
View user's profile View All Posts By User
Tsjerk
International Hazard
*****




Posts: 1850
Registered: 20-4-2005
Location: Netherlands
Member Is Offline

Mood: Mood

[*] posted on 8-10-2019 at 03:50


You could cut out the damaged part and reconnect the wires with something like this. Then put some tape over the connector.
View user's profile View All Posts By User
Praxichys
International Hazard
*****




Posts: 1022
Registered: 31-7-2013
Location: Detroit, Michigan, USA
Member Is Offline

Mood: Coprecipitated

[*] posted on 8-10-2019 at 05:12


If you're worried about it, just cut out the damaged part and make the cord shorter. I've done this a couple of times having accidentally cut cords with both a circular saw and an electric edger.

Cut out the damaged area, strip both ends, slide small heat shrink tube over each conductor and a large one over the whole cord, twist conductors together, solder, shrink the tubes to cover the conductors, then shrink the larger one to contain the others. For my outdoor cords I usually put some silicone caulk or dielectric grease under the heat shrink to waterproof the whole thing.

As mentioned, most strain reliefs are standardized and you can probably find a replacement cord if you're willing to open the case.
View user's profile Visit user's homepage View All Posts By User
Deathunter88
National Hazard
****




Posts: 405
Registered: 20-2-2015
Location: Beijing, China
Member Is Offline

Mood: No Mood

[*] posted on 8-10-2019 at 07:03


Honestly you're better off keeping it as is, you might just make it worse by trying to replace it. Based on your description of (a few seconds), I have no idea why people think the internals could be damaged, unless your rubber suddenly changed into a superconductor of heat.
View user's profile View All Posts By User
woelen
Super Administrator
*********




Posts: 7007
Registered: 20-8-2005
Location: Netherlands
Member Is Online

Mood: interested

[*] posted on 8-10-2019 at 07:08


I agree with Deathunter88. As long as the cord is not damaged too much, keep it as is. Wrap some tape around it, just to be sure. I myself have similarly damaged cords on some equipment, with dents in the isolation of half a mm or so. No problem at all.

If you take apart the heater, then you may introduce a bigger risk of electrical shock, if things do not fit nicely together after replacing the cord.




The art of wondering makes life worth living...
Want to wonder? Look at https://woelen.homescience.net
View user's profile Visit user's homepage View All Posts By User
phlogiston
International Hazard
*****




Posts: 1291
Registered: 26-4-2008
Location: Neon Thorium Erbium Lanthanum Neodymium Sulphur
Member Is Offline

Mood: pyrophoric

[*] posted on 8-10-2019 at 13:08


Hardware stores sell special heat-resistant cords for equipment that gets hot, like a clothes iron. The outer coating looks like it is some kind of fibrous ceramic material. They are inexpensive.
Seems like a better replacement than the usual rubber or PVC cords.




-----
"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer
View user's profile View All Posts By User
SWIM
International Hazard
*****




Posts: 570
Registered: 3-9-2017
Location: 26 Ancho street
Member Is Offline

Mood: I feel more the way I do right now than I ever have before

[*] posted on 8-10-2019 at 13:48


So I'm not quite clear on what you mean by hotplate.

If You're talking about a Corning or other lab type hotplate, especially a nice brand like Corning, I might be tempted to try some of the recommended fixes above.

But if it's like the hotplate I used for many years which was just a single burner kitchen hotplate I bought for $15 (USD) Then I'd just leave it the way it is.

The damage is shallow and you taped it up. That ought to do.

My old hotplate was the kind where the stuff to be heated sat on a flat metal coil that would get red hot when turned up.
I think back on all the reactions I did that way (Even making some pretty nasty stuff) and I'm amazed that I never cracked a flask. I even used to heat RBFs on that thing, with the coil contacting maybe 2% of the flask.

Either I was very lucky, or Ace Makes some great glassware.
(Probably a bit of both)









Do you want red P?
Eat lots of beets
View user's profile View All Posts By User
Murexide
Harmless
*




Posts: 40
Registered: 1-12-2018
Member Is Offline


[*] posted on 8-10-2019 at 17:04


So the hotplate is a cheap ebay hotplate magnetic stirrer sold widely. Doesn't have temperature control functionality, used to be sold for about $50.

You can't find them anywhere now, they're replaced with the tempearture control variant (it says up to 100 degrees C, but I think it actually can go a lot higher -anyone have any experience with these - https://www.ebay.com.au/itm/Value-1000ml-Magnetic-Stirrer-Mi... ).

I have very little experience with electronics and as a result any modification I make will probably make the situation worse.

Here's some photos of the hotplate / damage for reference (last photo shows damage)




Attachment: 1 (1.5MB)
This file has been downloaded 101 times

Attachment: 2 (982kB)
This file has been downloaded 94 times

Attachment: 3 (926kB)
This file has been downloaded 90 times

Attachment: Damage wrapped with tape (1.5MB)
This file has been downloaded 93 times

Attachment: Damage uncovered (317kB)
This file has been downloaded 103 times
View user's profile View All Posts By User
Deathunter88
National Hazard
****




Posts: 405
Registered: 20-2-2015
Location: Beijing, China
Member Is Offline

Mood: No Mood

[*] posted on 8-10-2019 at 17:53


Quote: Originally posted by Murexide  
So the hotplate is a cheap ebay hotplate magnetic stirrer sold widely. Doesn't have temperature control functionality, used to be sold for about $50.

You can't find them anywhere now, they're replaced with the tempearture control variant (it says up to 100 degrees C, but I think it actually can go a lot higher -anyone have any experience with these - https://www.ebay.com.au/itm/Value-1000ml-Magnetic-Stirrer-Mi... ).

I have very little experience with electronics and as a result any modification I make will probably make the situation worse.

Here's some photos of the hotplate / damage for reference (last photo shows damage)




You are fine.
View user's profile View All Posts By User
Sulaiman
International Hazard
*****




Posts: 2723
Registered: 8-2-2015
Location: Walsall UK but on extended Holiday in Malaysia
Member Is Offline


[*] posted on 8-10-2019 at 20:02


Based on the photograph, I would just wrap some pvc tape over the melted area and not worry about it.
As the damage was casued by a brief exposure to high temperature it is likely that the internal insulation is OK.




CAUTION : Hobby Chemist, not Professional or even Amateur
(suffering from separation of me and my chemistry stuff)
View user's profile View All Posts By User

  Go To Top