Earthing Arrangement- confused

[steptoe]

How exactly would that cause a danger?

the earthing in your house is now at 230v potential, and you are reliant on AN other to have a suitable protective device to disconnect the fault.

 

[Andy™]

but....

it ia not 230v. its tied to neutral/star, so although it will have a voltage, it wont be 230v, or anywhere near. it will only go to 230v if the neutral goes O/C

 

[spinlondon]

the earthing in your house is now at 230v potential, and you are reliant on AN other to have a suitable protective device to disconnect the fault.

Ignoring the suitable protective device, say there isn't one.

How is it a danger?

 

[steptoe]

[quote name='Andy

 

[Andy™]

its TNS, so its at 230v

its not. its tied to earth.

think about it - if you have a high current flowing to neutral (i.e a shower), the neutral is at or around 0V. its not at 230v.

you then touch neutral or a metallic part connected to PME), you dont die (since its not live)

 

[spinlondon]

its TNS, so its at 230vcos its at 230v

what part of it is it you dont understand?

you touch 230v you could get a shock and possibly die.

THERE IS NO FUSE ON THE EARTH

Not so, touch 230V and you will only get a shock, if there is somewhere for the current to flow.

In this case, the earth is at 230V, so where will the 230V flow to?

 

[steptoe]

Not so, touch 230V and you will only get a shock, if there is somewhere for the current to flow.In this case, the earth is at 230V, so where will the 230V flow to?

Im sure that I once read somewhere that that is something to do with how people get electrocuted, could be wrong mind, I usually am.

I really must read up on how electric chairs work again, must be something to do with how they strap you in.......

the path of least resistance,

so as long as you can prove that they woman at number 37 died because she was negligent in touching a conductive pipe after coming out of the shower then all is honky dory in cuckoo land.

 

[PBC_1966]

[quote name='Andy

 

[spinlondon]

Im sure that I once read somewhere that that is something to do with how people get electrocuted, could be wrong mind, I usually am.I really must read up on how electric chairs work again, must be something to do with how they strap you in.......

the path of least resistance,

so as long as you can prove that they woman at number 37 died because she was negligent in touching a conductive pipe after coming out of the shower then all is honky dory in cuckoo land.

You obviously read it wrong.

Electric chairs work by the current flowing through a person.

Why would a woman touching a conductive pipe be killed?

You're the one who believes an extra rod is dangerous.

Why don't you explain why?

 

[steptoe]

You obviously read it wrong.Electric chairs work by the current flowing through a person.

Why would a woman touching a conductive pipe be killed? because its at 230v potential

You're the one who believes an extra rod is dangerous.

Why don't you explain why?

how many times do you need the term parallel paths explained to you?

Im starting to really give up on simple things like this,

I may well be incompetent, but at least I understand the basics,

like someone wiser than me once said,

anyone can be an electrician,

the difference is knowing how not to fry someone.

 

[Andy™]

how many times do you need the term parallel paths explained to you?Im starting to really give up on simple things like this,

I may well be incompetent, but at least I understand the basics,

like someone wiser than me once said,

anyone can be an electrician,

the difference is knowing how not to fry someone.

how many times do you need basic ohms law explained to you? you will not get 230v unless neutral goes O/C. in which case, even without the rod, you would still have 230V

 

[PBC_1966]

Im sure that I once read somewhere that that is something to do with how people get electrocuted, could be wrong mind, I usually am.I really must read up on how electric chairs work again, must be something to do with how they strap you in.......

To sustain a shock there has to be a difference of potential across two (or more) points of the body. In the electric chair it's done by using electrodes on the head and one or both ankles or lower legs, then applying an initial voltage of about 2000V across them (give or take a few hundred, depending upon the system).

But you could walk barefoot along the conductor rail of an electrified railway track without getting shocked, just so long as you can find a way to jump on and off the rail so that no part of your body is touching anything else at the same time as you're in contact with the live rail. No difference of potential between your feet, so no shock, even though your entire body would be at several hundred volts relative to earth.

 

[steptoe]

[quote name='Andy

 

[spinlondon]

how many times do you need the term parallel paths explained to you?Im starting to really give up on simple things like this,

I may well be incompetent, but at least I understand the basics,

like someone wiser than me once said,

anyone can be an electrician,

the difference is knowing how not to fry someone.

If you understand the basics, then you should understand, that for current to flow, there has to be a difference in potential.

If you have equipotential bonding, then there is no difference, and therefore no current flow.

This is the principle on how Faraday cages work.

So if all your extraneous-conductive-parts are at the same voltage, where will the current flow through a person to?

 

[spinlondon]

and please explain to me the relation of N to T in a TNS or TT situation.

Considering that we are discussing a PME installation, what does the relationship matter?

 

[ianmacd]

Considering that we are discussing a PME installation, what does the relationship matter?

I assume you actually mean tn-c-s installation on a pme network?

 

[Andy™]

and please explain to me the relation of N to T in a TNS or TT situation.

try this approach steptoe.

next door has TT and a dead short to earth. because of Ra, not enough flows to blow fuse (no RCD). you have TNCS with an earth rod

for this, we will assume no common metallic services, and that neither property has gas/water

now some of this fault current may travel to your earth rod, through earth conductor to service head, to neutral and back to star.

in this case, 'ground' between the rods is your resistance. PD between both rods will most likely be around 230v. but there will be no or little voltage on your system.

still think you will get 230v?

then think of this

get your shower wired between L&N. it will work happily, and earth voltage will be at or around 0v

now wire the same shower between live and your earth rod (simulating current on the rod from another property). shower will still work as normal, and earth voltage will still be the same as though it was wired L-N

if you still dont get it, try explaining what part you dont get, since this all seems to be one way - you constantly saying its dangerous but have not yet stated any reasons as to why, despite me and other trying to say how its not.

 

[ianmacd]

This is the principle on how Faraday cages work.

Erm. No. A Faraday cage requires a closed conductor so no electrical forces can exist within it. That is not the same as a chicken wire ball so the surface potential is the same but electrical forces can still exist within it.

 

[spinlondon]

I assume you actually mean tn-c-s installation on a pme network?

I actually mean either, as they are the same.

 

[ianmacd]

I actually mean either, as they are the same.

WTF? No they are not.