Discuss Main bonding and parallel earth paths in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:   American Electrical Advice Forum

Reaction score
6
Hi all I was wondering if anyone could shed some light on an issue I cant seem to get my head around, say we had a metal socket earthed and a water pipe with main bonding, I touched the both of them in fault condition on socket (live touching metal box) now i understand the bonding puts the pipe at the same earth potential so no difference between the box and the pipe so no current will flow and I wont receive a shock.

Now this confused me as when we have parallel earth paths in say a socket circuit via metal trunking and conduit, this reduces our zs reading as fault current flows down the paralle paths.

How are both these actions not the same surely me touching both the earthed box and bonded conductor creates a parallel earth path?

Any help appreciated the theory of this has been annoying me for days.
 
Would it help to remember that electricity follows the path of least resistance?
So you are standing on the ground, but you have maybe rubber soles, fairly high skin resistance.
Some electricity would flow through you to ground, most would be diverted directly to earth via the main bonding and CPC.
This of course is vastly simplifying things.
There have been some interesting and informative threads on touch voltage on here in the recent past.
 
This one for example:
 
Also remember that the fault in the socket should disconnect the supply quickly removing the risk
 
To the MET.

The fault path you create is socket - pipe - MET (not earth) and this is at the same potential as the circuit which has faulted socket - CPC - MET.

Hence all extraneous paths require boning to the MET.

You'd hope some OCPD or additional protection would have activated though.
 
Would it help to remember that electricity follows the path of least resistance?
So you are standing on the ground, but you have maybe rubber soles, fairly high skin resistance.
Some electricity would flow through you to ground, most would be diverted directly to earth via the main bonding and CPC.
This of course is vastly simplifying things.
There have been some interesting and informative threads on touch voltage on here in the recent past.
What I understand as path of least resistance wouldn't it go through the earth wire and through me down the bonding cable. As I am acting as a parallel earth path? ...I'm confused haha
To the MET.

The fault path you create is socket - pipe - MET (not earth) and this is at the same potential as the circuit which has faulted socket - CPC - MET.

Hence all extraneous paths require boning to the MET.

You'd hope some OCPD or additional protection would have activated though.
I understand cpc is connected at the Met also via main board, so why me touching faulty socket box and bonded water pipe, how am I not creating a parallel earth path this is the confusing part for me
 
What I understand as path of least resistance wouldn't it go through the earth wire and through me down the bonding cable. As I am acting as a parallel earth path? ...I'm confused haha

I understand cpc is connected at the Met also via main board, so why me touching faulty socket box and bonded water pipe, how am I not creating a parallel earth path this is the confusing part for me
You are, only one of less resistance than a copper CPC.

You'll get a crack but not a whack, unless the CPC is broken (hence the protective devices not activating) then you'll get a whack and have to hope the circuit is well designed.
 
You are, only one of less resistance than a copper CPC.

You'll get a crack but not a whack, unless the CPC is broken (hence the protective devices not activating) then you'll get a whack and have to hope the circuit is well designed.
I need to borrow that expression! It's very descriptive.
 
Yes that is correct
Hi further to my question the other day I have another hypothetical if you could help not sure if I am correct and if not why.

So same again a socket box (no fault condition) just a load on the socket. And an unbonded water pipe. It is my understanding earth and neutral connected together at distribution side (in any earrthing system) so they will both be same potentiol rising to 230v with load.

So the water pipe having poor resistance through mass earth to transformer as it is not bonded would cause a potential difference. (Not 230v)

Thus current would flow even when not in fault condition.

If I am wrong please explain.

Help muchly apreciated
 
Hi further to my question the other day I have another hypothetical if you could help not sure if I am correct and if not why.

So same again a socket box (no fault condition) just a load on the socket. And an unbonded water pipe. It is my understanding earth and neutral connected together at distribution side (in any earrthing system) so they will both be same potentiol rising to 230v with load.

So the water pipe having poor resistance through mass earth to transformer as it is not bonded would cause a potential difference. (Not 230v)

Thus current would flow even when not in fault condition.

If I am wrong please explain.

Help muchly apreciated
Current would flow if I was touching non fault box and water pipe
 
Hi further to my question the other day I have another hypothetical if you could help not sure if I am correct and if not why.

So same again a socket box (no fault condition) just a load on the socket. And an unbonded water pipe. It is my understanding earth and neutral connected together at distribution side (in any earrthing system) so they will both be same potentiol rising to 230v with load.

So the water pipe having poor resistance through mass earth to transformer as it is not bonded would cause a potential difference. (Not 230v)

Thus current would flow even when not in fault condition.

If I am wrong please explain.

Help muchly apreciated
Please ignore,I've confused myself here the above is nonsense ignore haha
 

Reply to Main bonding and parallel earth paths in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc
This website was designed, optimised and is hosted by Untold Media. Operating under the name Untold Media since 2001.
Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock