Main Earth size

[SLIPSHOD & SLAPDASH]

When compiling a EICR or Installation cert what do you fill in for the main earth size when usually a 16mm cable has been taken to the MET but (again usually) the suppliers short cable is 2.5-4 mm ?  This would normally only arise with a TNS supply

 

[Sharpend]

Are you not only concerned with the consumers earth supply in which case it’s 16mm,

the other piece is considered supply side? 

i.e. on a standard tncs you don’t see the earth on suppliers side only the 16mm that is connected on consumer side of install? 

It has always interested me in how the supplier can have smaller csa cables than what we have to abide too. Surely that just defeats the need for us to consider so many factors when selecting cable sizes???

 

[SLIPSHOD & SLAPDASH]

To keep things clear lets forget about TNCS for now & only TNS. Apart from where a 951 clamp has been fitted  i have never  seen anything bigger than 4mm (but imperial) cable, usually 2.5 soldered on. Even with a 951 clamp on a older install this may only have a 4-6 or 10mm cable connected & we should not be touching it.

So back to the original question, what do people here fill in on the certs/reports for main earth size ?

Also more recently DNO's are fitting a braided cable for the earth from the sheath to a MET, what csa is that ?

 

[Sidewinder]

I don’t bother with ESQCR, only BS7671, however I may put an observation in.

 

[SLIPSHOD & SLAPDASH]

So only 2 people are prepared to say  what  size cable they note on a certificate, the cable on the consumers side of the MET or the suppliers side ?

 

[Andy™]

only whats covered by 7671, from the DNO's earth terminal, not the scabbly bit of string they use between their clamp and their terminal block

if tis really small then maybe noted as an observation

 

[kerching]

Me?

consumers side 

wih a note if theirs looks  

 

[binky]

if I fit 16 or10 mm that's what I state on the cert - the suppliers bit is sod all to do with me, just as the suppliers tails and incoming supply is sod all to do with me.

 

[Blue Duck]

Me, whatever comes out of the the consumer unit and is connected to the MET /suppliers cable or service head.

 

[Murdoch]

In these cases I was taught to the Ze at the suppliers connection as a check, and if the reading was within normal scope then just record the size of the earth cable from the MET to the cu ....

 

[binky]

if you do Ze at rhe board, with main earh disconneted it's the same thing basically - resistance of 2 ft of 16mm earth is something like 0.001 Ohms

 

[Doc Hudson]

So only 2 people are prepared to say  what  size cable they note on a certificate, the cable on the consumers side of the MET or the suppliers side ?

Document the size of the conductors that connect to the distribution board / CU and its associated MET. So the Earth would be noted as 16mm if that is what's connected to the customer MET. I can't see this being much different to the supply tails noted as 25mm, when the tails from the meter back to the cut-out are only 16mm.  With of course any additional comments or observations noted as you see appropriate.  

Doc H. 

 

[Ardet R]

You are normally asked for the size of the earthing conductor, according to the definition this is from the means of earthing to the MET, i.e. the bit of scraggly wire from supply cable to a small bolt on the back board.

However when documenting I, as all above, state the size of the cable from MET to CU, because it is the only relevant one I can do anything about.

 

[Tony S]

Although it doesn’t fall in the remit of BS7671. If you’re unhappy with the supplied earth connection you could use a constant pressure spring and braid, not a BS951 clamp.

 

[Sharpend]

Although it doesn’t fall in the remit of BS7671. If you’re unhappy with the supplied earth connection you could use a constant pressure spring and braid, not a BS951 clamp.

I believe they are reserved for use by DNO engineers only for the sole purpose of providing suitable earthing connection to their cable. 

Perhaps they have different torque drivers as well as different regs? 

Who knows who cares!! :C  

 

[Sidewinder]

BS951's are a bad idea!

However, an older version of BS951 used to suggest & allow that use!!!

The current one does not.

Really we should not be touching the suppliers cable connection.

Yes they do work to different standards, they all have their own based on their own industry body guidance EAWR & ESQCR.