section of EIC

[nickp78]

hi, in the section of an EIC covering Particulars Of Installation Refered To In The Certicate which covers the Main Protective Conductors when filling out the part for the earthing conductor which in a domestic situation would be the copper cable from the suppliers fuse to the board MET, if you had a situation where you have 4 three phase DB,s which are all fed from a large radial circuit and you where adding an additional circuit to one of the four DB,s what would you enter into the section for earthing conductor, would it be the earthing to the large SWA supply cable or the earth as it enters the sub DB

 

[Tester Steve]

Hi Nick,

If I read you correctly, it would be the earth that is protecting the individual DB.

Steve.

 

[nickp78]

thanks for the reply, i have a large SWA cable coming from substation which tee,s off from large SWA cable from large 100A switch fuse unit down to DB, it does this 4 times to supply 4 x 3 phase DB,s, the problem is when it tee,s off to the Distribution board in 4 x 35mm pvc cable in conduit for 2 of the DB,s and smaller SWA for the other 2 DBs, when completeing a new circuit at one of the DB,s what would i enter into the section for earthing conductor for an EIC, would i enter steel or conduit in this section as the conduit is the earth conductor for the DB,

 

[Tester Steve]

Nick,

I assume that the conduit is SUITABLE to be an earth, that the connections to the conduit are SOUND AND that they are visible AND give the correct readings for an earth then put steel. If not, you need to run a seperate conductor. Same with the swa, is it terminated correctly at BOTH ends and are the readings ok?

Hope this helps.

Steve.

 

[nickp78]

thanks again, i am getting 0.22 ohms Ze at the DB between each phase and frame ( cannot rule out any parallel paths ), my example EIC,s and all my testing and inspection books refer to domestic and state should be copper but i have checked the regs and earthing conductor can be many things and only states that cables of certain size 10mm or 16mm must be copper

 

[trebor]

I think you may be getting away from your original ? that is what is the earthing conductor, there is only one earthing conductor this eic section refers to and that is the the one at origin whether it be domestic or industrial, the others you are referring to are no more than cpc`s for the distribution circuits which will be recorded as Zs forthe same

There is only one Ze and again that is at origin of supply

 

[nickp78]

hi all, this is the second time i have heard this argument can anyone please explain

 

[Sintra]

hi all, this is the second time i have heard this argument can anyone please explain

The earthing conductor is always at the origin from the supply authority cut outs to the MET.

 

[NoSparks]

hi all, this is the second time i have heard this argument can anyone please explain

The nieve answer is that "this is the way the regs specify it" as said above but...

(Sorry I might be slightly off topic). I believe this demonstraights the futility of many of the measurements we are expected to make! The real question is " Is the earthing system throughout the installation fit for purpose". and to demonstraight this has been examined we are asked to give information about the installation that does not necessarily apply in all cases.

This is one instance where the fitness for purpose is not answered by the EIC questions. Suppose the earth were 16mm Cu, is that fit or should it be 25 or 35? what difference if the earth is 100mm long or 25m long? [The regs go further along this line than the EIC does.]

In this case I believe Steve has the right idea. "Is the earth from the DB all the way back to the source fit?" Unfortunately the EIC does not ask that, it asks for the parameters of the earth, so that is what we have to give.

 

[Tester Steve]

NoSparks,

That is what I was trying to get across to the OP, is it sound and are the measurements ok. If they are, it doesnt matter what the material is.

Steve.

 

[nickp78]

thanks again guys, all the points use have raised are all vaild points, i think when i was doing my 2391 practical there where two boards one fed the other and we had two circuit schedules and took a Ze reading for both boards and recorded them, i am satisfied with the earthing system and that disconnection times will be met by the appropriate protective devices