Electric Shock

Because you may not have yet made a circuit through part of your body. Basically, two parts of your body must touch two different points with voltage between them.

But say a stove element (one of those curly ones)... if I stick one hand on that and the other onto an earth pole - surely I'm not going to get a shock? (A burn, maybe, but not a shock).

Thanks - I didn't realise they were constructed that way - now it makes sense.

Whatever you do, dont try it out! Dont touch an oven element when heated either.

Just saying!

Too late - I'm now in the burns unit.

Bugger! You need to ask more questions before you touch anything . . .

However, damage can occur so that electrical contact is made. In that case, a shock is possible.

What he said there is very important. There can be micro cracks in the ceramic that do not affect current flow when a pot or pan is on the element, because the pot or pan is resting above the conductor (NiCh wire) on top of the rest of the intact ceramic coating. But your finger, because it is more flexible and relatively wet, can make contact.

And by the way, most toasters do NOT have ceramic coated heating elements, so you CAN be shocked by touching them. They heat up so much faster that your own protective reflexes would pull you back first. That's why you must NEVER use a metal utensils to remove toast if the toaster is plugged in, the utensils delays the heat transfer, but not the electricity transfer.

...which is why a toaster, such as the one in #7↑, is normally fitted with a double pole switch that opens both contacts while ejecting the toast at the end of the toasting time. If some silly nerk puts a fork in there to get it out, there is little risk of an electric shock with both live and neutral disconnected, even if they are the wrong way round in the plug.

However, there is nothing stopping shock if the fork is inserted while the thing is still toasting, which is why kitchen circuits installed to the latest edition of British Standard 7671 are fitted with 30mA residual current devices to disconnect the supply and prevent that prime walrus getting a fatal electric shock. At least, that's the theory, anyway.

Re PWSlack comments in post 8 about 30mA RCD's. These are common now and mandatory, but 50 years ago they were a novelty. I was involved with a company that sold them (pioneered them actually), and to demonstrate how effective they were I thought I would touch the live wire to show that they tripped out.

What seemed a good idea at the time turned out to be rather daft.

Yes the RCD tripped and I am still here to tell the tale, but I got an almighty poke in the few milliseconds it took to trip. And I bashed my elbow in the recoil. And worse from a sales point of view, the customer who was interested in RCD's to prevent electric shock, was left with the clear and obvious impression that they did nothing of the sort.

Hence the importance of qualifying the claim by adding 'fatal'. As PWSlack has done.

A modern installation to the latest edition of British Standard 7671 would have a 30mA residual current breaker on a cooker circuit so that, were the fault situation in #3↑ arise, then human contact with a live part would cause it to disconnect the circuit before the individual received a fatal electric shock. At least, that is the theory.

turn it up higher next time

Don't try it with bare feet!

actually my original question was a bit misleading - I have never touched a toaster element... with anything...

But it's pretty easy to touch the electric stove elements - good to know the layer of ceramic is there!

qq

Most stove elements with the outer metal layer actually earth ground that outer layer. If not directly, then through the metal frame of the stove.

Thanks - interesting post!

Although some individuals have a difficult time understanding or believing it, under certain condition you can get a shock from a 12 volt car type battery.

Get your body nice and sweaty, dip your hands in sea water and touch both terminals of the battery with fingers of the same hand. You should feel a slight shock across the hand. DO NOT ATTEMPT THIS WITH BOTH HANDS, ONE ON EACH TERMINAL! Done that way, across the heart, could cause a potentially fatal heart attack or defibrillation of the heart.

Case in point- I have a 20' wooden sailboat. It has a stainless steel center board (metal plate that sticks out the bottom of the boat into the water) that is about 4' long. This centerboard in grounded to metal parts of the mast for lightning protection. I sail in salt water.

The negative terminal of the battery for lighting is also grounded as is required. I was sitting in the cabin with my feet in a small amount of bilge water after sweating a lot. I touched a positive wire in the electrical panel and felt a small shock across my hands, arms and leg. What had happened was the good conductor of the sweat on my body, my feet in the salt water of the bilge, my one hand gripping the metal centerboard and touching the positive wire created a path of low resistance which caused the voltage to flow through me. Much to my surprise I felt the low voltage, 12 volts, shock and could reproduce it. My feet in the salt water, the metal centerboard in the salt water, the negative terminal being grounded, sweaty body, sweaty and salty hands and touching the positive wire all combined to have electricity shock me enough that I could feel it. Again, this was only 12 volts!

For anyone with an implanted defibrillator, don't even think about doing this! It could cause your defibrillator to activate and shock your heart. If that occurs it is much more painful than this 12 volts was.

Good Luck, Old Salt

"I felt the low voltage, 12 volts, shock and could reproduce it"

MASOCHIST!

There is a difference between an oven element and a toaster element.

1. Never touch either when they are on.
2. Never use a metal instrument to get anything out of said toaster.
3. The oven element is surrounded by ceramic and covered in a metal jacket, so you wont get shocked.
4. However, with a toaster it is usually a NiChrome wire element, meaning that you put the hot to one end and the neutral to the other and you get a giant resistor that glows and toasts your bread and there is no outer sheath.
5. Here is a diagram:

Good luck and keep your hands out of where they don't belong!
BA

I had questions like this as a child, at about 4 I unscrewed a light bulb from a lamp, stuck my finger in the socket and turned the switch...it felt 'tingeley'. I think I was only touching the center post, no good ground. Kind of like Ben Franklin's kite flying during a thunder storm. Experiment...then reason it out! Or maybe reason it out, then experiment.

If the stove's heating element wasn't encased in ceramic then placing a metal pot or frying pan on it would short out the element, think about it.

New toaster elements read in the GigaOhms when you measure from one lead to the other with a megger. Therefore you will get such a small amperage when you touch it because most of the amps are converted to heat.

Back to school, Gary.

Help me, has Ohms Law been found to be unconstitutional by the supreme court of electricity?

My wife's toaster is a 1,000 watt unit. Since it is a 120 volt unit Ohm's law would have said that the current was 8.3 amps, (P = I * E, therefore I = P/E) since 1,000 watts/120 volts = 8.3 amps. Now if I solve for R, resistance, the calculation should be R=I/E according to Ohm's Law. That would mean, E being 120v and I being 8.3 amps) the resistance, R, should be 120v/8.3amps or 14.4 ohms.

If a megger measurement was one GigaOhms, 1,000,000,000 ohms, then I=E/R would be I = 120/1,000,000,000 or 0.00000012 amps which equals 0.12 microamps.

Most things of this nature tend to increase their resistance when heated. For a similar example, the resistance of a light bulk is at it's lowest when unlit and highest when lit. Granted a heating element that is insulated will heat up with electricity applied to it but touching it will produce a burn due to heat and not electricity since it is electrically insulated. Take an non-insulated heating element, touch it with electricity applied to it and you would get a burn due to thermal and electrical contact.

Perhaps the calibration of the meggar needs to be checked. Or perhaps we all need to recognize the updating of Ohms Law.

Good Luck, Old Salt

A megger will measure the resistance of the insulation not the resistance of the circuit (unless you deliberately do so).

And yes, I did do it with a calibrated megger (required calibration once a year to ensure consistent readings) because that's what is required in the naval shipyard. The lowest acceptable reading from a megger on naval lighting circuit is 500,000 Ohms.

http://www.navsea.navy.mil/CNRMC/SERMC/SSRAC1/nsi/13nsi/009-22_FY13.pdf

garyrich2000-

My answer was based on the statement: New toaster elements read in the GigaOhms when you measure from one lead to the other with a megger.

As many know, including you and I, a megger is a unit that is connected to wires that form an open circuit in order to measure the conductance between the wires. When indicated in ohms this is normally every high.

Based on the above quote the megger was connected to each lead of the toaster element. A toaster element is a conductor having a low resistance from lead to lead therefore the megger would indicate a very low resistance, not a high resistance when the megger is used in the normal manner. If the toaster element was connected to an open SPST or DPST switch in series with the element the megger would indicate a high resistance if there was no defect in any of the components.

My viewpoint is that this original was probably composed in a little rush, as most of use will admit we do, and it was simply an incorrect keyboarding incident. I understand what you are stating but others may not be as fortunate.

Good Luck, Old Salt

Push the toaster lever down. There is a contact that breaks the circuit. Some need power to pull in the relay that connects the elements.

Thank you for the response Mr Salt. and others on this site whether it's positive or negative. If I make an incorrect statement I welcome the corrections to fine tune my responses. Without such feedback I'd be at risk to repeat the same remark. So again, thank you much.

The megger reading I pictured is across the ceramic insulation in 3 phase reading each phase to ground and each phase to each phase while disconnected from the wiring. While in single phase, this high ohm reading would be from one terminal to ground but not terminal to terminal as I mistakenly stated.

Yes, but you also said "Therefore you will get such a small amperage when you touch it because most of the amps are converted to heat." which is totally false. Depending where you touch it, (live side?) and what you are connected to elsewhere (bare feet on conductive floor, e.g.), you may have low resistance and mains power - with Niagara Falls behind it. Kentucky Fried, anyone?