Friday, February 18, 2011

Electrical Magic

Well its not that easy but Electricity does have magical effects, like the standard 120 volt 15/20 amp house hold receptacle
can easily go from 120Volts ac to 230 volts easier than you think .
Electrical service to most homes is provided by 3 wires at 120/240 volts
there is a neutral wire with zero voltage on it that serves as a return path and 2 hot wires each carrying 120 volts each that when combined produce 230 volts for heavy appliances such as stoves ,dryers etc.
when a new Electrical service is installed these days there is a ground wire attached to the homes Cold water Pipe plus a wire is attached to a Driven ground rod or two which serves as a
back up. But this was not always the case , before the 80’s many homes only had the Ground wire to the water pipe .No ground rods ,and this is were the trouble could develop.
The ground wire on a service has several roles. One role is to keep the voltage level coming into the house at a level 120/230 volts the other is to carry away a lightning strike. The third is a solid ground is essential to carry away fault current when a circuit is shorted.
and the forth and most important is it can temporarily serve as a neutral connection if the neutral wire coming in from the service would disconnect its self., due to corrosion or accident of nature .
If You loose both the neutral wire and ground wire connection all 120 volt outlets within the home can now have 230 volts coming out of them because there is no return path for the current. This condition happens more often than you would suspect and is responsible for hundreds of fires yearly across the country but it is often goes unrecognized because Electrical fires can be so hot as to destroy all of the evidence. There have even been cases were vandals or arsonists have cut neutral wires coming into homes and business in an attempt to start a fire but this could be fatal to someone trying this trick as often a very large electrical arc occurs . But some times there are clues left when a neutral connection has been lost , such as lights going low and blinking before a Fire or even lights turning on by them selves talk about spooky effects and often if a home has Allunimum siding you can see marks were the voltage was trying to make ground by going back through the homes service cable , in particular you will find that the paint behind were a service wire has been straped is missing .In one of my customers homes he had lost the ground wire in his home in one section and because he had metal lath in the plaster walls when a receptacle broke down and made contact with a metal wall switch everything metal in 3 rooms became electrified had my customer not immediately shut off his service he would have been coming home to a fire that evening. My Dept was recently at a house fire were 120 wiring run thru metal duct work had rubbed to the point it made contact to the metal and because the duct work was not solidly grounded the power worked its way to the outside service wire which finally completed the circuit allowing the wood around it to ignite due to the heat build up, yes even dry wood can conduct electricity under the correct circumstances.
as happened in this residence.
This condition also can happen when you have an old original 120 volt 30 amp electrical service from the 20’s
Changed over to a new 100/200 amp 120/230 volt service. Many of these old 120 volt services can be found in old towns all over Pennsylvania I know of at least 30 such services in Penn Hills Pa. area
When an Electrician converts these services he will put all of the old 120 circuits all on the
same A or B phase 120 wire of the service if he does not follow this precaution he can send 230 volts through out the house . Even though I have done hundreds of these conversions
and was trained in Knob and tube wiring because you were still allowed to extend these circuits all the way up to the early 80’s .I even have been fooled by this 230 Phenomena and blown out light bulbs with 230 volts
this is why after this type of service has been converted that the electrician must absolutely test
each and every light switching circuit and receptacle to make sure he has not feed 230 volts through it. this 230 phenomena happens because old knob and tube wiring often had several
circuits sharing the same neutral .In some homes they would take 1 single neutral wire up through a house and tap off it any where it was easy to get to.
Even in today’s modern wiring when you run a 120/230 Edition receptacle circuit through a home were a 14/3 or 12/3 wire is run to a group of receptacles so that each side of the duplex receptacle is a dedicated circuit certain precautions with the neutral wire must be taken to prevent the 230 volt phenomena .Instead of putting the neutral wire in and out of the
Receptacle screws the neutral wire must be attached to other neutral wire and then a pigtail wire run to the receptacle neutral screw. Failure to follow this procedure can result in 230 volts being present in the socket if the neutral wire falls off. Again many Fire investigators miss this code requirement not being followed as a possible cause when doing investigations and the cause of the fire can be staring them right in the face. If you suspect you have a fire that has happened under these circumstances get an Electrical professional with a high degree of experience to confirm it for you. Fire due to electrical malfunction
does not give an answer when the is answer is an educated guess and can not be directly pointed at what caused it.
When the causes of Electrical fires is more definitely pointed at .Codes can be better defined .The Entire set of NFPA codes including The National Electrical Code has been written because of actual tragedies and this is why it is critical to get the correct information from fires to prevent them . These type of Electrical fires also point as to why Arc fault breakers and ground fault circuit Interrupters should be used.
The tragedy of electrical fires can be lessened thru better education and prevention.

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