Electrtic shocks from water taps

[hoover]

Have to check this out later. House is on a tt system. Probably more like tingles but will take a while to go through everything i suppose. Anybody any hints which might speed up the process?

 

[jjjinx]

I do understand what your saying but misguided it isn't, its physics!

A common known fact that as any electrician will know whether its 1 volt or1000s it will take the most conductive path, this is why we put lightning conductors on buildings.

There are a lot of varables conserning being electrified but the conductivity of the body is part of it.

Please see info below:

Lightning strike info:

source: Science Centre Singapore: ScienceNet|Physical Sciences|Magnetism/ Electricity

More conformation of resistance of the body through lightning strikes: Lightning Injuries: eMedicine Trauma


The current in an average lightning bolt is as high as 30,000 amperes with 1,000,000 or more volts. The short duration of about 1-100 milliseconds limits, but does not prevent injury. There are several mechanisms of lightning injury. The most severe is a direct strike, either on the victim or on some object the victim is holding such as a golf club, tripod or umbrella. A "side flash" occurs when lightning hits a nearby object and jumps to the victim. Ground current injures the victim when lightning strikes the ground nearby and it spreads to the person. Rarely, people maybe injured or killed indoors while using the telephone or taking a shower. Burns may occur from jewellery, clothing or other heated material. Finally, blunt injury and trauma may occur secondary to the shockwave from a lightning strike or from a resulting fall. Direct strikes cause maximum injury because the entire charge of the lightning passes through or over the person's body. Because of the short duration of contact during a lightning strike, often not enough voltage is transferred to break the insulating effect of the skin; therefore, the charge typically passes along the surface of the body in a process known as "flashover". The extent of injury depends on a number of variables, including amperage, voltage, current pathway, length of contact, resistance of the body, and the victim's relationship to discharging electrical fields. When the charge merely passes over the victim's body, less damage occurs. People hit by lightning suffer both extreme heat and damaging electricity from the bolt. Direct hits are not the only danger however. In open terrain, nearby strikes also can electrocute. Actually, most people, perhaps surprisingly, survive lightning strikes because you have a greater likelihood of being in the close proximity of a lightning strike, as opposed to being hit directly. So, far more people survive lightning strikes than are killed by them. Lightning fatalities usually are caused by cardiac arrest; the lightning causes the heart to stop. Lightning-strike victims who show signs of cardiac or respiratory arrest need emergency help quickly. Prompt, aggressive cardiopulmonary resuscitation (CPR) has been highly effective for the survival of victims of lightning strikes. Those who survive a lightning strike often have serious health problems as a result, such as losing control over some parts of their body or losing their memory, particularly their short-term memory.


Conductivity of the human body:


There are a lot of factors involved and not every person has the same electrical resistance. For instance, men tend to have lower resistance than women. Just like for the resistors used in electronics, the resistance of a person’s arm depends on the arm’s length and diameter. Resistance goes up with length and down with diameter. Since men tend to have thicker arms and legs (more muscle), they usually have lower resistance. (An implication of this is that the lethal current for men is higher than that for women.) A rough value for the internal resistance of the human body is 300-1,000 Ohms. Naturally, the resistance also depends on the path that electricity takes through the body - if the electricity goes in the left hand and out the right foot, then the resistance will be much higher than if it goes in and out of adjacent fingers.

Within the body, the tissues with the greatest resistance are bone and fat - nerves and muscle have the least resistance. That said, the majority of the body’s resistance is in the skin - the dead, dry cells of the epidermis (the skin’s outer layer) are very poor conductors. Depending on the person, the resistance of dry skin is usually between 1,000-100,000 Ohms. The skin’s resistance is much lower if it is wet or burnt/blistered. This means that when a person is electrocuted in real life, the body’s resistance drops as the skin is burned. To determine a person’s total resistance, just add together the resistance of each part of the body - remember that the electricity must pass through the skin twice (on the way in and on the way out), so the total resistance is:

Rtotal = Rskin(in) + Rinternal + Rskin(out)

Another interesting point to consider is that in addition to acting like a resistor, the epidermis acts like a capacitor if placed in contact with a piece of metal (the underlying tissue is like one plate of a capacitor and the metal surface is like the other plate - the dry epidermis is the less-conductive material or "dielectric" in between) . In cases of electrocution by a DC voltage source, this capacitive property has little importance. But if the electrocution is by an AC source, the epidermis’s natural resistance is "shorted out", allowing the current to bypass that part of the body’s resistance and making the body’s total resistance much lower.

 

[mechelec]

I take it your talking about doing this with the circuit dead?

No offence but do you really need me to tell you to follow safe isolation procedures before you work on anything electrical. I assumed, obviously wrongly that before anyone removed the main earth that the installation would be isolated and the N-E test carried out on the incoming side of the main switch that would be in the OFF position.

Dont forget you will need a screw driver and loop impedence tester to carry out the above

 

[Darkwood]

Well reserched Jjjinx although i understand their are several factors if not more that determine the damage done by lightning i was only refering to a small area where a person drenched to the skin although has lower resistance has a higher percentage chance of survival as the lightning tends to still flow over the body on the surface water rather than through it which as you've shown would be a path of greater resistance, my knowledge came from a recent documentory dealing with lightning victims and survival rates.
What is nice though with your indepth approach is you've thus contradicted your own post about man and womens body resistance as you've quite rightly pointed out in your new post that men usually have lower body resistance than women and not as formentioned in your previous post.
Its nice to see someone take an interest in what hes written and spend the time to reply with such an answer although its all just fun and banter at the end of the day, its these indepth and researched answers that are the most educational.

 

[jjjinx]

No offence but do you really need me to tell you to follow safe isolation procedures before you work on anything electrical. I assumed, obviously wrongly that before anyone removed the main earth that the installation would be isolated and the N-E test carried out on the incoming side of the main switch that would be in the OFF position.

Dont forget you will need a screw driver and loop impedence tester to carry out the above

dude your sarcasim is sad and assumption is the mother of all ...... thats why sparks die!

there are new guys on here & some not even qualified sparks trying to rewire houses, we are all here to help each other.

No offence Pippyboy but I don't know how experienced you are and I was trying to cover an important base incase you thought he new wat he was talking abt.


Darkwood
I think you missed the bit about the woman being sweatier or more likely moistorising giving a possible reason for her conducting in the property and the guys maybe having dryer hands!

I wasn't debating who would receive the worst shock in a thunderstorm only that the resistance of the body was a factor.

It seems you & mechelec have had bad days, I'll leave it like that.