Electric safety rule ?

Jan 09, 2006 18 Replies

Some years ago a guy promoting his anti-rust spray, he clam that the anti-rust spray have good dielectric, he than spray on the lamp holder & put in to a pail of water with power switch on, this surprise me that does't shot circuit. This recall me that some kattle ( found in the hotel ) , the heater element connected to the live wire was not insulated in the water, but it does not cause any electrical problem when boiling the water. It had confuse me in the electrical safety rule, that is live wire should not contact with water. Can any members help me in this questions ? Thanks. Regards.



Relatively clean water has enough resistance so that only a moderate current will flow Also, the bucket is isolated from ground (I'd use a plastic one). I'd not sit in a bathtub and for that kind of demonstration, however.

The heater element in the kettle...I guess thats what you mean ...like an electric tea kettle..... is insulated. The nichrome heater element is encased in a insulating material inside the outer tube.

possibly he was using de-ionised water :)

because the water in the vessel is not in electrical contact with anything outside the appliance.

do not pour the water into a metal pan while the kettle is plugged in.

Bye. Jasen

What you saw, that you thought was the heating element, was only the external casing, or jacket, for the actual heating element. The heating element is insulated from the casing by some sort of electrically insulating, but heat-conductive, material.

Hope This Helps! Rich

no. not always. some of the older ones had bare nichrome, I've seen some that heated by conduction too.

Bye. Jasen

No.. thats not entirely true.

In some countries (Aus for example) There were electric jugs which were just a pottery jug, with a plastic lid to keep your fingers out, and the element was an EXPOSED coil of tungsten on a porcelain former in direct contact with the water. At 240 volts they worked great. Predecessor of Fast Heat Kettles.

A simpler water boiler was a tinplate container of about 1/2 a gallon with 2 electrodes suspended in the water and connected directly to the

240 volt mains. Boiled the water quite soon or sooner if the water was harder. Of course this setup would not qualify as DOUBLE Insulated nor would it get UL Approval. But boys will be boys. What adventures our children are missing.
John G Wot\'s Your Real Problem?

A, it's probably not "non-insulated", it just _looks_ like it. Get out your meter and check!

And B, ordinary water is a good enough insulator that its resistance across the terminals will be orders of magnitude higher than the resistance of the element.

Here's an experiment - dissolve a couple of spoonfuls of salt in your water, and see if _that_ shorts it out!

All of the standard disclaimers apply, of course. :-)

Good Luck! Rich

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Hi John.You are right. I got this electric jug from Austalia during my holiday. Thanks Regards

it does produce hydrogen, but because if the high voltage most of the energy goes into heating the water.

if you were to put salt water in there it would blow the fuse. but tap water has low enough conductivity to have most of the current flowing in the nichroome.

Bye. Jasen

yeah I've seen them (In australia) we never had them in New Zealand the rods were metallic (brass?) and uninsulated and ran directly too the bolts that backed the contacts for the "plug" (inline socket) on the end of the power cord.

I saw one that had two metal disc electrodes in the bottom spaced about

15mm apart. could be interesting if that one boiled dry.

Bye. Jasen

I can assure you the device known as an Electric Jug and use by most austalians to boil water for tea or coffee for many years had a bare wire element wrapped around a porcelain rectangle about the size of a match box and suspended by the conecting rods directly into the water. The power was pluged into a connector under the hinge of the lid so it was not possible to put anything in the water without first removing the power.

There are several for sale on Ebay.

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On this link there is a picture of the element alongside the jug.

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John G Wot\'s Your Real Problem?

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Will someone please take an ohmmeter to one of those elements? Anything uninsulated on the mains is a death trap, and I can't imagine any civilized country allowing such a thing to be sold. Doesn't Aus. have something like UL or CSA?

Thanks, Rich

IEC. Like the rest of the world. UL/CSA applies only in N.America.

Graham

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Yes it is UNinsulated and yes in careless hands could be dangerous but I can not remember a problem being reported. We do have a certification authority and these have been OFF the market for many years now.

John G Wot\'s Your Real Problem? >

It's 22awg approx nichrome wire, I doubt very much that they have a way to insulate anything that fine.

when the cord is attached it's impossible to open the lid of the jug more than a crack.

as far as safety it doesn't seem much worse than an electric toaster...

These devices are antiques...

Bye. Jasen

What about those cheapie "vaporizer" humidfiers? Been a few years since I looked at one, but as I recall it was just a couple of electrodes immersed in a chamber of water. (You had to add salt if your water wasn't conductive enough.) Seems like that is not so different than the jug from Oz.

Best regards,

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis

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