earth leakage

[i=p/u]

can anyone give me insight to earth leakage, i know travels down earth path etc.. just a few cases of why iy happens , what type of equipment you know it happens on and how to test for earth leakage, isit a live test???? thanks...

 

[Sparky Ninja]

I came across this the other day..



I havn't read through it all yet, but it looked informative.

 

[Des 56]

Electricity has this overwhelming need for the electrons to get back to where they originated
Its route to that source is always the easiest path
If it has an easy route and another becomes available then dependant on the restrictions it has ie curent carrying capacity and the value of how much it is resisted, then it may deviate,it matters not to the electron, as long as it gets back to source

When there is leakage,it is a poor term for saying it has found an alternative route to that origin
We hope that what goes down one conductor is matched by what goes back by another conductor,but that is never a realistic hope
There is always some current that finds an easier path back to origin,that is what we like to call earth leakage

We dont want it to happen.but it is mostly unaviodable
A test for the amount of leakage could be the measurement of current flow down the one conductor and compared to the current on the return conductor
Another method could be to measure the current down the earth cable,which we hope is very low,perhaps using a clamp meter
Earth leakage can be assessed by an insulation resistance test,it that will indicate whether a current flow would be likely given the value of resistance to earth

 

[johnboy6083]

IT equipment is known for having relatively high leakage per unit. As a rule of thumb I was told 0.03 amps per PC. So using this rule only 10 PC's on one RCD. recently did a job in a school and 10PCs per ring pulled 25A (normal current, not leakage) too,

 

[i=p/u]

nice info sparkies... so what your saying johnboy is 0.03 per pc , is ten would equal the 30 mA rcd limit thanks again

 

[Guest123]

Section 543.7 of ol' red has information on high protective conductor currents.

 

[i=p/u]

i dont have big red book as you gus call it , im only working my way through on site guide , told to get for next year, keeping an eye for a cheap 1 on ebay thanks lenn

 

[Guest123]

Have a look here......