ABC Inventors - electrical safety device

Hi Franc

Yes I saw the show and was going to post almost exactly what you have said.

He also claimed it was pretty cheap ie around a dollar to build.

Frankly, I am a bit sceptical of claims that it would do anything more than an RCD and/or a sensitive circuit breaker, especially as you got virtually no information as to how the thing works at all. I would be happy to be proved wrong.

Dave Goldfinch

In the text Wayne said "It works" but the description is very vague on details and seems to not understand 'Double Insulated'. He says it can be built into the device. Well if the switch is in the hair dryer in the water how does it keep the EXCESS electricity out of the water?

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John G

Wot's Your Real Problem?

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> - Franc Zabkar
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> Please remove one 's' from my address when replying by email.

It seems to be a device to be built into or retrofitted into an appliance, as is implied in the video, and as such, the only way I can think it would work is to "learn" the typical current/voltage usage patterns of the device its connected to - and if there is any sudden change in these patterns- (that 'looks' consistent with human contact or "hazardous" leakage for example?) that seems suss, then it shuts off the power.

If this is the case, (its in the appliance) then surely it would provide no protection for the cord, plug etc of that appliance, and these probably need to be protected a lot more than the innards of the appliance, as cords are so easily damaged, and often touched by the consumer ? for that matter - if his magic device is INSIDE the hairdryer - and the dryer is then thrown into the bathwater - it might very well do a great job of cutting the power to the dryer's internals, but how is it going to stop the current still flowing down the cord and into his device ? (Put a massive short across the active/neutral to make the house fuse blow maybe ? :)

I also find it strange his implication that appliances with 2 pin plugs "seem to be unable to work effectively with an RCD compared to 3 pin ones". As I see it - an RCD will work just as well with 2 pin as

3 to protect a human body from electric shock, as long as you have an earth connection, (ie: the ground you are standing on) and if you didnt have a ground connection to your body when you touched the active lead, you aren't going to get a shock anyway, unless you grab both active and neutral.

I didn't see the process where the panel interviewed him on the device

- and there are no details even remotely on how it works, either on his website or the URL you gave above. In fact the whole site seems to totally avoid the theory of operation and instead give tons of vague"consumer' type information about how wonderful it is - and will save the world etc etc.

also, how many cases would there be of people accidentally coming into contact with both active and neutral connections *simultaneously* in domestic situations ? remember that unless you grab both of them at the same time, (within the trip time of the RCD) then the one you touch first - will set the RCD off and stop the current flow anyway)

"KLR"

** Imagine a small kiddie picking up one of those mini two pin female plugs as used on many items like shavers, small audio and VCRs and DVDs. The kiddie then decides to put the plug in its mouth while the other end is plugged in and live.

The RCD will not trip.

** Not at all - when standing on a wood or carpet floor there is not enough earth leakage to trip an RCD.

One has be in contact with an earthed object to do that.

BTW

I agree with your other comments about the Inventors device.

........... Phil

"Franc Zabkar"

** My two cents worth is this:

The Protex device trips a normally closed latching solenoid switch upon detection of a significant AC voltage appearing on the metal case or internal metal ( non live) parts of the particular Class 2 appliance - as measured relative to the neutral wire. Pretty much, this makes it a submersion detector.

Such AC voltage detection - if applied to external metal parts would have to be via a low value Y2 rated capacitor so not to breach Class 2 requirements.

............. Phil

Correct, he said such on the show when asked.

On Thu, 05 May 2005 11:24:01 +1000, KLR put finger to keyboard and composed:

But how do you make a device like that for $1? And how could you distinguish leakage from the load changes that result from normal usage? Furthermore, the ABC URL states that "Protex is an electrical safety switch that can be installed ... into a home?s electrical power box or switch board". The inventor also agreed that it could be fitted inside a GPO. This means that one device could be protecting several appliances.

Unfortunately the panel were not knowledgeable in this particular field, so they were unable to ask pertinent questions. The inventor's website is annoying in that it requires you to log in, and is heavily reliant on flash. Whenever I see a Macromedia intro, I am immediately suspicious of the quality of the content.

- Franc Zabkar

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Please remove one 's' from my address when replying by email.

On Thu, 05 May 2005 13:51:18 +1000, Terry Collins put finger to keyboard and composed:

Then why go to the trouble of building it into your appliances when you could mould it into a universal plug? In fact the inventor agreed that the device could be incorporated into the GPO. The ABC URL goes on to say that "Protex is an electrical safety switch that can be installed at the manufacturing level into new household appliances (toasters, kettles, hair dryers) or into a home?s electrical power box or switch board." This says to me that it's a two-wire device (remember the toaster demo), and that it's probably nothing more than an automatically resettable RCD, despite the inventor's statement that it senses voltage. The switching element would be mechanical, as it is claimed that "it does not use power until a fault is detected, meaning it does not generate heat". A triac would get quite hot if it were asked to deliver 2000W to a kettle, for example. I suspect that latching could be provided by an SCR or a transistor pair. Maybe one end of the solenoid coil is connected to neutral and the other end to the gate of an SCR via a zener diode. Perhaps that's what the inventor meant by "sensing voltage". You'd probably need a diode bridge and a capacitor as well. But can all that be made for a dollar?

- Franc Zabkar

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Please remove one 's' from my address when replying by email.

On Thu, 5 May 2005 10:54:14 +1000, "John G" put finger to keyboard and composed:

My impression of the man was that he was either short on understanding, overawed by the occasion, or just deliberately vague.

- Franc Zabkar

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Please remove one 's' from my address when replying by email.

On Thu, 5 May 2005 10:54:14 +1000, "John G" put finger to keyboard and composed:

The ABC URL states that the device could be made waterproof by encapsulating it. Assuming there are no exposed parts upstream of the safety device, then the hair dryer should not "leak" electricity.

- Franc Zabkar

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Please remove one 's' from my address when replying by email.

"Franc Zabkar"

** See my "two cents worth" .

Doing that does not allow connection to metalwork in a Class 2 appliance.

** But it looks like he has not tried it. ** I prefer not to assume the inventor is a liar.

........... Phil

"Franc Zabkar"

** Exactly - the inspiration and whole idea of the invention is to instantly isolate a Class 2 hair dryer or shaver that lands in the bath tub or wash basin.

.............. Phil

I reckon its all a croc of shit. The only way to get electrocuted to death if you have an RCD, is if you grab a neutral cable in one hand and an active cable in another while standing on an insulated floor. The current has to pass through the heart or through the brain to kill you. If you read some stories with regard to electric chairs, you will find that it is actually quite difficult to kill someone with electricity.

Even a baby that sticks a live two pin plug in its mouth will be ok. Might just get a big shock but certainly not death. Even then the child will have to be insulated from earth.

Same goes with a dryer in a bath tub. A bath tub is often connected with metal drain pipes to earth. So the RCD will go off if the current is not balanced between active and neutral. If it is balanced enough to not set the RCD off, then there is little risk to the occupant in the bath tub.

"Heywood Jablome"

** If you read accounts of accidental electrocutions - you will find it is absurdly easy to die.

Do you remember the one where the 3 y.o girl died when using a hairdryer while sitting on the back step - when her older brother threw small bucket of water onto her ???

** You have proof of this ???? ** You have proof of this ???? ** A carpet floor will do that. ** This last one has GOT to be a subject for the Mythbusters .

........... Phil

Phil

That would seem to be a plausable explanation but what about if it was built into a GPO ? There would be no way to sense the voltage on the case or internal metal without an extra wire back to the GPO.

Perhaps this is why he claims that it 'could' be built into a GPO but he hasn't done it yet - because it is impractical ?

BTW could you use a triac instead of a solenoid switch or would this cause problems with some appliances ?

Dave Goldfinch

Yes. But how do you get both of them into a bath?

"Dave Goldfinch" "Phil Allison"

** AFAIK that is a purely hypothetical product. It would need to sense voltage on the appliance earth wire - so breaking the rules about earth continuity. ** IMO, 100% yes.

** The safety trip MUST break both the active and neutral conductors ( in case of A-N reversal) and provide galvanic isolation - ie an air gap or solid insulation. A triac is just not on.

........... Phil

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significant AC voltage means the person is well and truely shocked !!!

An electrocuted person can be electrocuted by leaks that dont cause such signficant voltage.

The case of a fridge or heater has to be connected to earth.

I think he just means its impractical to put such a stupid device in there.

Mabye you could only tolerate the stupid thing in a hair dryer.

triacs cant be used as a safety device - they dont work well enough - not reliable, and their reliable performance as as with isnt good enough for safety.

double insulated .. well the level of insulation isnt relevant, he was probably trying to think of what doubling the insulation could do....

(my wires are double insulated - two layers of cling wrap !)