Main Earthing Terminal

Sparky Stu · Mar 16, 2011

Hello all, just a quick question. I was having a nose around my brothers house he has recently bought and noticed that there was no MET where the main earthing conductor and bonding comes from.

The system is a TNC-S and there are earth clamps on the gas and water pipes also supplementary bonding in bathroom.

Now it looks to me that the C/U has been moved from its original place to allow for an extention to be built as the meter is located in a box outside of the property and on the other side of the wall is a 80A RCCB which isolates the whole house when switched off.

I have had a look inside the C/U suspecting that the bonding may have been connected to the earth bar inside but only found 1 main earth connected to bar and all relevent cpc's connected to bar in the order that the circuits follow.

My question is should a MET be visible as i suspect that it may be above the ceiling under the floorboards or is it possible that there isnt one.

telectrix · Mar 16, 2011

MET shoud be accessible. looks like a bit of demolition work is needed. enter Del Boy , Rodney and Grandad.

pushrod · Mar 16, 2011

TBH i'm not quite sure what you are asking ? Is the earth bar in the CU not just acting as the MET or are you worried that the main protective bonding conductors are not connected? Can you not just test for continuity?

Sparky Stu · Mar 16, 2011

Not to sure if bonding conductors are connected as with my installation at home i have a small type of earth bar that is separate from the C/U which has all Bonding connected to it and then an earthing condutor which goes to the C/U. At my brothers i cannot see this nor find it so assumed it may be under floorboards. Currently i am training to be a spark but didnt know if there is another way that the bonding conductors could be connected without using an met

rodney12 · Mar 16, 2011

Could it be in the outside meter box? best way is to test for continuity

tony mc · Mar 16, 2011

Try and trace the main earth from the CU and see if you can locate where it goes to.

It might be that when you trace it back you find the MET with the bonding conductors connected.
This might be next to your meter at the incoming supply point..

Don't want to offend as I don't know what experiance you have but do not disconnect any of the connections with the main supply switched on.

Failing that and if you do have concerns I would get someone in to have a look.