They say there are no stupid questions but I might be about to disprove that - PME

[Ken77]

I'm an not that familiar with TNCS systems at all, as almost every system I work on is TNS. My question is this, is there a way to tell if a system is in fact a TNCS system. There is one I am currently working on which is labelled as PME, but rather that taking it as gospel that this means it is a TNCS are there any visual tell-tale signs, as I don't want to connect the earth to neutral if it is a TNS.

Thanks in advance.

 

[Farmelectrics]

Re: They say there are no stupid questions but I might be about to disprove that - PM

refer to earthing diagrams in on site guide or mant other electrical books

 

[Adam W]

Re: They say there are no stupid questions but I might be about to disprove that - PM

Why would you be connecting the earth to neutral anyway?

 

[GLENNSPARK]

Re: They say there are no stupid questions but I might be about to disprove that - PM

I'm an not that familiar with TNCS systems at all, as almost every system I work on is TNS. My question is this, is there a way to tell if a system is in fact a TNCS system. There is one I am currently working on which is labelled as PME, but rather that taking it as gospel that this means it is a TNCS are there any visual tell-tale signs, as I don't want to connect the earth to neutral if it is a TNS.

Thanks in advance.

with TN-C-S...both prospective short circuit current (PSCC)....and prospective earth fault current (PEFC) should be largely the same....

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dont forget a TN-C-S uses the neutral as the earth path....

 

[Farmelectrics]

Re: They say there are no stupid questions but I might be about to disprove that - PM

niceic snags and solutions earthing and bonding book all you need to no about earthing arrangements

 

[Top Cat]

Re: They say there are no stupid questions but I might be about to disprove that - PM

Why would you be connecting the earth to neutral anyway?

If it's PME he would.

 

[Adam W]

Re: They say there are no stupid questions but I might be about to disprove that - PM

If it's PME he would.

I always thought the neutral and earth should only be connected on the DNO side and only the DNO should be connecting them.

 

[GLENNSPARK]

Re: They say there are no stupid questions but I might be about to disprove that - PM

I always thought the neutral and earth should only be connected on the DNO side and only the DNO should be connecting them.

yes...otherwise you would have a TN-C system.....not allowed in the uk....

 

[Ken77]

Re: They say there are no stupid questions but I might be about to disprove that - PM

Glen to pick up on two points

Firstly PSC is 27a and PFC is 1483 a. Would this make you wary that PME label is incorrect?

Assuming it is a PME system (TNC-S) should I be getting the DNO to connect the earth.

Thanks

yes...otherwise you would have a TN-C system.....not allowed in the uk....

 

[GLENNSPARK]

Re: They say there are no stupid questions but I might be about to disprove that - PM

glen to pick up on two points

firstly psc is 27a and pfc is 1483 a. Would this make you wary that pme label is incorrect?

Assuming it is a pme system (tnc-s) should i be getting the dno to connect the earth.

Thanks

pscc=27a????

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whats your Ze?

 

[Ken77]

Re: They say there are no stupid questions but I might be about to disprove that - PM

Yes, 27a as PSC and 1483 as PFC.

ZS - is 8.59 ohms. Which is high and a fail I know, under anything other than a TT, which it isn't. (Yet anyway). Currently arrangement is that what probably a PME system which has never had main earth connected to it, and instead is clamped to metal piping surrounding the incoming supply conductors.

I might redo PSC tomorrow to be sure.


With regards to above, would you believe the PME label? And if so, would you connect the earth or request DNO to do it?

 

[telectrix]

Re: They say there are no stupid questions but I might be about to disprove that - PM

first check your readings. then call DNO .

 

[GLENNSPARK]

Re: They say there are no stupid questions but I might be about to disprove that - PM

you cant make any assumptions on values like that Ken....as Tel here....

 

[Ken77]

Re: They say there are no stupid questions but I might be about to disprove that - PM

Last thing, and I really appreciated the advice - in any case is always the DNO responsibiliy to connect earth to PME system.

Thanks again.

Ken

 

[GLENNSPARK]

Re: They say there are no stupid questions but I might be about to disprove that - PM

whats this about connecting earthing up to DNO equipment Ken?.....

 

[GLENNSPARK]

Re: They say there are no stupid questions but I might be about to disprove that - PM

Last thing, and I really appreciated the advice - in any case is always the DNO responsibiliy to connect earth to PME system.

Thanks again.

Ken

yes it is...

 

[Ken77]

Re: They say there are no stupid questions but I might be about to disprove that - PM

Cheers, thanks alot.