Ze Query

[Jacobssi]

My main bonding conductors on a TNCS system as well as my main earthing conductor are connected to my distributors meter. When doing a Ze I can't disconnect the main bonding conductors because the meter is sealed therefore giving me' parrallel paths.
Would I write this as a limitation on a certificate and enquire the figure with the distribution board?

 

[mikhailfaradayski]

possibly a dim question, but why do your earthing and bonding go to a meter?

If that were the case, is it not possible to disconnect at the gas/water and test Ze at the CU?

is a photo possible of the meter in question?

 

[STI]

Probably also a dumb question, does the main earth not go to your CU if not how is the installation earthed. Is it from the CU to the pipes only ? The main earth should go from the CU to the main suppliers fuse (at least the housing of it ) is this what you mean by it goes to the meter.

 

[Risteard]

Probably also a dumb question, does the main earth not go to your CU if not how is the installation earthed. Is it from the CU to the pipes only ? The main earth should go from the CU to the main suppliers fuse (at least the housing of it ) is this what you mean by it goes to the meter.

The earthing conductor must go to the Main Earthing Terminal (which may or may not be in the distribution board). If it isn't, then a circuit protective conductor must be brought from the MET to the dis. board.

The main protective bonding conductors must also go to the MET.

 

[Chri5]

The Op is suggesting the MET is sealed in the meter housing, which I've NEVER seen.

If it was I'd break the seal and bring the MET out, since it needs to be an accessable testing point.

 

[Jacobssi]

So the main earthing conductor runs from the meter to the MET bar that is in my CU which my circuit protectors run to. But my two main bonding conductors, one running to my water pipes in the airing cupboard and one to the kitchen, both originate from inside the meter not the CU. I have yet to do a continuity on these but am taking a guess as I have two main conductors and two bonded pipes!! PS I live in a flat with the meter outside the door.

 

[STI]

Hi Risteard, sorry i probably was too light with words in my question to the OP. It appeared from the OP description there was no earth at the CU. The set up is clarified by the OPs' last post.

So to do the ZE in this case i guess you would also have to disconnect the main bonding conductors at the pipes as mikhailfaradayski said as they appear to be on the DNO side of the set up, as well as disconnecting the main earthing conductor at the CU

Or calculate the Ze or ask the DNO (GOOD LUCK!!) It depends on whether are you trying to get the practise testing or just want to know the Ze.

 

[Risteard]

Having no access to main protective bonding conductors certainly isn't satisfactory.

An MET should be installed and the earthing conductor terminated here along with main protective bonding conductors. Can't understand why they are in the meter!?!?!?!?!?!?!

 

[ban-all-sheds]

So the main earthing conductor runs from the meter to the MET bar that is in my CU which my circuit protectors run to. But my two main bonding conductors, one running to my water pipes in the airing cupboard and one to the kitchen, both originate from inside the meter not the CU.

 

[1john]

Can you cut them off and terminate them into a 4 terminal main earthing terminal with the main earthing conductor looped in and out of it?

 

[Risteard]

You can't loop the earthing conductor in and out of the MET because only the cable between the MET and the means of earthing is the earthing conductor.

 

[Jacobssi]

Not a bad idea John. BAS I will put up pictures later if I remember. I did the Ze for a EIC and with all bonding in place (main earthing disconnected) the result was 0.13 ohms

 

[Jacobssi]

Not a bad idea John. BAS I will put up pictures later if I remember. I did the Ze for a EIC and with all bonding in place (main earthing disconnected) the result was 0.13 ohms

 

[Jacobssi]

Sorry can't upload photos from an iPhone have to wait till my laptop is repaired.

 

[skenk]

Sure you don't mean 'cutout' rather than 'meter' that these bonding cables go to?

Presumably if you ticked the relevant box on the schedule of inspections for your EIC you must have found the bonding clamps, so can disconnect here?

As John1 says you can fit a new MET and terminate bonding and main earth here as long as there is 16mm to the cutout/'meter'.

quote:
"My main bonding conductors on a TNCS system as well as my main earthing conductor are connected to my distributors meter.

You did it for an EIC on your own house?