Post by thread:[OT] 240V anywhere

It seems like we have many heavy current experts around, so I can ask a question that's been with me for a while. Why do heavy current appliances (220V over here) only burn the 'live' contact in the plug and not the neutral contact. It is AC, right? If you can answer this question, you'd be answering one of life's two most puzzling questions for me. -- Friendly Regards Tjaart van der Walt spam_OUTtjaartTakeThisOuTwasp.co.za |--------------------------------------------------| | WASP International | |R&D Engineer : GSM peripheral services development| |--------------------------------------------------| |SMS .....tjaartKILLspam@spam@sms.wasp.co.za (160 chars max)| | http://www.wasp.co.za/~tjaart/index.html | |Voice: +27-(0)11-622-8686 Fax: +27-(0)11-622-8973| | WGS-84 : 26¡10.52'S 28¡06.19'E | |--------------------------------------------------|

Joe Lepine wrote: > The answer is IN the question. The "live" leg has voltage on it > (arching). The neutral is by definition at or near ground. I thought about this, but it is AC. Besides, how does this pin know it is close to ground and therefore not supposed to get hot? -- Friendly Regards Tjaart van der Walt tjaartKILLspamwasp.co.za |--------------------------------------------------| | WASP International | |R&D Engineer : GSM peripheral services development| |--------------------------------------------------| |SMS .....tjaartKILLspam.....sms.wasp.co.za (160 chars max)| | http://www.wasp.co.za/~tjaart/index.html | |Voice: +27-(0)11-622-8686 Fax: +27-(0)11-622-8973| | WGS-84 : 26¡10.52'S 28¡06.19'E | |--------------------------------------------------|

On Thu, 23 Jul 1998, Tjaart van der Walt wrote: > It seems like we have many heavy current experts > around, so I can ask a question that's been with me > for a while. > > Why do heavy current appliances (220V over here) > only burn the 'live' contact in the plug and not the > neutral contact. It is AC, right? > > If you can answer this question, you'd be answering > one of life's two most puzzling questions for me. I don't know why, but it's true. Here we have mandatory fault current trippers (tiled floors everywhere + hot & wet = first touch is the last one), so the explanation that the ground leakage through the 3rd prong removes the connection arcing at connect/disconnect if the hot prong touches first/separates last fails. However, I have a theory that is more or less chemical. I believe that the live prong sees a higher potential (even AC) over ground than the other prongs, and somehow this helps it build a thicker oxyde layer, which in turn causes more resistance in it in time, vs. the other prongs. The process is self-amplifying, with each connection making things worse. Alternately, the air and debris trapped in the copper on the live prong are 'more' than on the other one. Is this too far fetched ? You all know what amount of dirt collects on HV cables, AC or DC, in time. Ok, 220 V is not HV but then it takes 4 to 10 years for the socket to burn out. Ah, and 220 V is almost 1/3 kV pk-pk ;). Peter

On Thu, 23 Jul 1998 13:36:25 +0200 Tjaart van der Walt <EraseMEtjaartspam_OUTTakeThisOuTwasp.co.za> writes: >Joe Lepine wrote: > >> The answer is IN the question. The "live" leg has voltage on it >> (arching). The neutral is by definition at or near ground. > >I thought about this, but it is AC. Besides, how does this >pin know it is close to ground and therefore not supposed to >get hot? I wonder if the neutral pin makes contact first, so the hot pin is the one that actually has to make or break the circuit (and arc). Also, on 120 VAC plugs, the hot pin is narrower, perhaps increasing its resistance. Harold _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866]

Tjaart van der Walt wrote: > Why do heavy current appliances (220V over here) > only burn the 'live' contact in the plug and not the > neutral contact. It is AC, right? Consider the 'Live' wire as an electrical inlet and the 'Neutral' wire as an electrical return. Your appliance asks for current which enters through the 'Live' wire, uses the current up, and returns nothing out the 'Neutral' wire. If your appliance asks for more current than the copper 'Live' wire can handle, then the 'Live' wire or connector burns. I hope this clears this up Ed Arnold hilanderspam_OUTbellsoth.net

> Tjaart van der Walt wrote: > > > Why do heavy current appliances (220V over here) > > only burn the 'live' contact in the plug and not the > > neutral contact. It is AC, right? > > Consider the 'Live' wire as an electrical inlet and the 'Neutral' wire > as an electrical return. Your appliance asks for current which enters > through the 'Live' wire, uses the current up, and returns nothing out > the 'Neutral' wire. If your appliance asks for more current than the > copper 'Live' wire can handle, then the 'Live' wire or connector burns. > > I hope this clears this up > > Ed Arnold > @spam@hilanderKILLspambellsoth.net > If neutral returns nothing then why have a neutral wire? Victor Moisey Institute of Child Health Red Cross Childrens Hospital Private Bag Rondebosch 7700 Cape Town South Africa

> Tjaart van der Walt wrote: > > > Why do heavy current appliances (220V over here) > > only burn the 'live' contact in the plug and not the > > neutral contact. It is AC, right? > > Consider the 'Live' wire as an electrical inlet and the 'Neutral' wire > as an electrical return. Your appliance asks for current which enters > through the 'Live' wire, uses the current up, and returns nothing out > the 'Neutral' wire. If your appliance asks for more current than the > copper 'Live' wire can handle, then the 'Live' wire or connector burns. > > I hope this clears this up > > Ed Arnold > KILLspamhilanderKILLspambellsoth.net > That is a very suspicious claim, you are saying that no current flows through the neutral wire? If that is the case on your appliances I'd check your earth system out! Appliances don't just "use current up", you can't pour current down a wire and watch it go to nowhere, it has to exit back out of the appliance from somewhere, and it's meant to be the neutral wire. As you correctly say, it is a return. Mike Rigby-Jones RemoveMEmrjonesTakeThisOuTnortel.co.uk

On Wed, Aug 19, 1998 at 12:14:58PM +0000, Victor Moisey wrote: > If neutral returns nothing then why have a neutral wire? Under some circumstances there is current returned via the neutral wire. For example, if you were to place a block of dry ice in your refrigerator, the 'fridge will have to operate in inverse mode to warm the ice up to the preset temperature. This means it will return current via the neutral wire, which will go back into the electricity grid. Similarly, if you have a piece of toast in a toaster that catches fire, it will heat the toaster instead of the other way around, this will also cause current to be returned via the neutral wire. In any case, many appliances that are not 100% efficient will always return some current via the neutral since they take in more current than they actually need. If you disconnect the neutral, the excess current backs up and stops the appliance from working, since it cannot get rid of the excess current and becomes clogged with electrons. You could dump the excess current to ground, but the electricity authorities do not like this (it's wasteful) - that's why they encourage you to install earth leakage detectors. Oh, and the other major need for it is when you switch a ceiling fan to run backwards, for winter use, it will actually draw current via the neutral wire instead of the active, because the motor is running backwards. Hope this helps. Cheers, Clyde -- Clyde Smith-Stubbs | HI-TECH Software Email: spamBeGoneclydespamBeGonehtsoft.com | Phone Fax WWW: http://www.htsoft.com/ | USA: (408) 490 2885 (408) 490 2885 PGP: finger TakeThisOuTclydeEraseMEspam_OUThtsoft.com | AUS: +61 7 3354 2411 +61 7 3354 2422 --------------------------------------------------------------------------- HI-TECH C: compiling the real world.

On Wed, 19 Aug 1998, Clyde Smith-Stubbs wrote: > > Under some circumstances there is current returned via the neutral wire. > For example, if you were to place a block of dry ice in your refrigerator, > the 'fridge will have to operate in inverse mode to warm the ice up > to the preset temperature. This means it will return current via the neutral > wire, which will go back into the electricity grid. > > Similarly, if you have a piece of toast in a toaster that catches fire, > it will heat the toaster instead of the other way around, this will > also cause current to be returned via the neutral wire. Those devices called "ground fault circuit interrupters" are designed to prevent this by breaking the circuit. Electric power companies do not like having power produced by anyone but themselves, so they lobby for the installation of GFCIs, which are already required by electric code in many circuits. The big lie is that it is for "protection". But whose protection? I say it is to protect their profits, and prevent people from reducing their electric bills with modified toasters and other such devices. :-) Cheers, Bob

Bob Blick wrote: {Quote hidden}> On Wed, 19 Aug 1998, Clyde Smith-Stubbs wrote: > > > > Under some circumstances there is current returned via the neutral wire. > > For example, if you were to place a block of dry ice in your refrigerator, > > the 'fridge will have to operate in inverse mode to warm the ice up > > to the preset temperature. This means it will return current via the neutral > > wire, which will go back into the electricity grid. > > > > Similarly, if you have a piece of toast in a toaster that catches fire, > > it will heat the toaster instead of the other way around, this will > > also cause current to be returned via the neutral wire. > > Those devices called "ground fault circuit interrupters" are designed to > prevent this by breaking the circuit. Electric power companies do not like > having power produced by anyone but themselves, so they lobby for the > installation of GFCIs, which are already required by electric code in many > circuits. The big lie is that it is for "protection". But whose > protection? I say it is to protect their profits, and prevent people from > reducing their electric bills with modified toasters and other such > devices. > > :-) Do I detect some subtle leg pulling here 8-). I'm not an electrician, but.... I should point out that in some countries the neutral is tied to earth, usually at each fuse box. Other countries don't do this. So if you grab the "active" wire while standing on a damp concrete floor in Australia you will get a zap. Where the neutral is not tied to earth you won't. GFCI or residual current devices make sense here where neutral is tied to earth. They operate on the principle that all the current in matches all the current out, and that is switching back and forth at 60/50hz . Any current that doesn't make it out is going to earth (where neutral is tied to earth) and this may be through a human body so the device trips. I found this out when I was working under my VW Kombi with a lamp on a lead and I caught the lead between the car and the engine mount ... flash ... bang ...trip . Someone else may wish to explain how you get a neutral when you have three phase distribution with no neutral wire. Nick

I'll try to bring this back on topic... So whatever happened to installing solar panels, gas turbines, wind turbines, or whatever, and producing more power than you use? I knew several "frontier" types who did this, and I believe the law says the power company has to buy the excess electricity if you dump into their grid. I've also read about some people running their meters backwards using this approach (and some other hokey power generators and some knowledge of the meter's properties - but we'll not go there), and winding up with a negative power bill that way... I've been toying with the idea of putting up both an "egg-beater" wind turbine, and a bank of photovoltaic cells (I can do 5-10KV pretty easily with very little loss - lots of wind and sunshine here in Oklahoma ;), and selling the power back to the grid. I've got GFCI outlets all over my house. Is my powerplant going to be tripping my GFCI outlets all the time? I guess I should probably build a regulator with inputs from my own plant and the power grid, which will automatically draw from the grid when needed, and use my plant the rest of the time, and dump everything back into the grid (after my batteries are charged, that is ;). What do you think? Sound like a good PIC application, or is that overkill for a voltage regulator ;) Ken >> circuits. The big lie is that it is for "protection". But whose >> protection? I say it is to protect their profits, and prevent people from

On Wed, 19 Aug 1998, Ken wrote: > selling the power back to the grid. I've got GFCI outlets all over my > house. Is my powerplant going to be tripping my GFCI outlets all the time? > > Ken > > >> circuits. The big lie is that it is for "protection". But whose > >> protection? I say it is to protect their profits, and prevent people from Whoa, sorry, I took Clyde's joke and ran with it. You won't trip any GFCIs by powering the grid. GFCIs are not a "secret government plot" :-) Except for the little transmitters in them. :-) -Bob

Clyde Smith-Stubbs wrote: > > On Wed, Aug 19, 1998 at 12:14:58PM +0000, Victor Moisey wrote: > > > If neutral returns nothing then why have a neutral wire? > > Under some circumstances there is current returned via the neutral wire. > For example, if you were to place a block of dry ice in your refrigerator, > the 'fridge will have to operate in inverse mode to warm the ice up > to the preset temperature. This means it will return current via the neutral > wire, which will go back into the electricity grid. Clyde your resistors are in backwards! ;-} -- Neil Cherry http://home.att.net/~ncherry RemoveMEncherryTakeThisOuTworldnet.att.net

At 07:24 AM 19/08/98 +0000, you wrote: {Quote hidden}>On Wed, 19 Aug 1998, Clyde Smith-Stubbs wrote: >> >> Under some circumstances there is current returned via the neutral wire. >> For example, if you were to place a block of dry ice in your refrigerator, >> the 'fridge will have to operate in inverse mode to warm the ice up >> to the preset temperature. This means it will return current via the neutral >> wire, which will go back into the electricity grid. >> >> Similarly, if you have a piece of toast in a toaster that catches fire, >> it will heat the toaster instead of the other way around, this will >> also cause current to be returned via the neutral wire. > >Those devices called "ground fault circuit interrupters" are designed to >prevent this by breaking the circuit. Electric power companies do not like >having power produced by anyone but themselves, so they lobby for the >installation of GFCIs, which are already required by electric code in many >circuits. The big lie is that it is for "protection". But whose >protection? I say it is to protect their profits, and prevent people from >reducing their electric bills with modified toasters and other such >devices. > >:-) > >Cheers, >Bob > > Ah my kingdom for a power factor of 0 :-). Why not stop all your electrical products from producting "heat", that would be easyer!. Anyway what is this neutral stuff? I always thought that that black wire (Or blue) was infact an earth return (Bonded to earth as the junction box in the house, and then connected to local earth at the house which then feeds back to the earth grid at the substation), or the centre of a star delta generator (Via earth)? :-) :-) Dennis

So, basically, the idea is to make sure that you are as near to 100% efficient, and are returning no power to the grid. Could a battery charger operate at a high enough efficiency to be used as a sort of "mop" to make sure that you aren't returning any power back to the grid? It should only take a fairly simple circuit to sense the current draw at the panel, compare that to the current on the neutral, and create an adequate load "downstream" to drain the current to 0A. Am I out of my mind? (it wouldn't surprise me - I understand DC much better than AC) On a more humerous side - there are no-doubt agreements in place between the util companies and the manufacturers of most electrical appliances to create inefficient, wasteful devices, so that the consumer pays for X number of electrons, but only uses 60% of them or so. This may become a crusade :) Ken -----Original Message----- From: Bob Blick <EraseMEbobTED.NET> To: RemoveMEPICLISTEraseMEEraseMEMITVMA.MIT.EDU <RemoveMEPICLISTspam_OUTKILLspamMITVMA.MIT.EDU> Date: Wednesday, August 19, 1998 9:35 AM Subject: Re: [OT] 240V anywhere <big snip> :)

At 12:14 PM 19.8.98 SAST-2, you wrote: {Quote hidden}>> Tjaart van der Walt wrote: >> >> > Why do heavy current appliances (220V over here) >> > only burn the 'live' contact in the plug and not the >> > neutral contact. It is AC, right? >> >> Consider the 'Live' wire as an electrical inlet and the 'Neutral' wire >> as an electrical return. Your appliance asks for current which enters >> through the 'Live' wire, uses the current up, and returns nothing out >> the 'Neutral' wire. If your appliance asks for more current than the >> copper 'Live' wire can handle, then the 'Live' wire or connector burns. >> >> I hope this clears this up >> >> Ed Arnold >> RemoveMEhilanderTakeThisOuTspambellsoth.net >> > >If neutral returns nothing then why have a neutral wire? > > It's a plot by the cable manufacturers to make people buy twice as much cable. BTW you do need to be careful not to energize a cable that is not connected to anything otherwise the electrons will fall out on the floor and bite you when you step in them. (g) Barry

Bob Blick <EraseMEbobspamspamBeGoneTED.NET> wrote: > Those devices called "ground fault circuit interrupters" are designed to > prevent this by breaking the circuit. Electric power companies do not like > having power produced by anyone but themselves, so they lobby for the > installation of GFCIs, which are already required by electric code in many > circuits. The big lie is that it is for "protection". But whose > protection? I say it is to protect their profits, and prevent people from > reducing their electric bills with modified toasters and other such > devices. If you produce electricity and dump it back into the grid, it will not trip your GFCI. The GFCI only trips if the hot and neutral current aren't balanced. This is done to make sure the current isn't going somewhere else, like through your person to ground. The GFCI really is there for your protection. It's not a sinister conspiracy to boost their profits. In general the utilities do not like you providing them with power. But the reason for this is also a safety matter. If there is a power outage, they don't want you putting power on the lines that they think are dead. Most states allow (or even require) that you sell any excess electricity you produce to the electric utility. However, in order to do this you are required to buy special switching equipment. Note that there's a reason why everyone isn't taking advantage of this and generating power for sale back to the utility: they only are required to pay your wholesale rates for the electricity you sell them. This is much lower than the retail rate that they charge you. Eric