Earthing Type

[daz1024]

Am I right in saying that if there is no earth connection to the suppliers cut out then the earth type is TT?
We have just moved into a property and there are currently 3 fuse boxes connected. All have a connection to the met which is not connected to the cut out. One does the majority of the house, one is for the garage and one much newer one is just for the cooker. The cooker one has a 30ma rcd and a 32 mcb in it. the garage one has a 100a main switch and a 40a mcb. Both of these boxes are labelled but the main one is not and has a number of circuits split between the main switch and an rcd. I have been told that if it is a tt system then the whole lot should be rcd protected and there is a lot that isnt. Is it possible that this is a different earth system and is it likely that its safe? Landlord just says it works dont worry

 

[davesparks]

If you have just moved in to a rented property (as I assume it is since you mention a landlord) then they have to have given you a copy of the electrical installation condition report (EICR) by law.

On the EICR it should specify what the earthing system is.
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I can't see the incoming supply cable properly in tbe picture, could you post a better picture of the incoming supply cable below the cutout?

 

[ipf]

I agree, a better picture required. There are four green/yellows, though. One CU and two bonds, maybe. What's the fourth?
Then again, there's more than one CU. Are the others local?

 

[pc1966]

The MET has to be earthed to somewhere.

If it is a TT system then it needs an earth rod, and it would need RCD incomer(s) or all-RCBO boards so all circuits can meet disconnection times in the event of a fault to earth/CPC.

As stated above, you should get a copy the EICR. If in any doubt then check it out - your profile says you are practising electrician so should be no real issue to verify the Zs at any outlet and if, as suspected, it is supposed to be TT then see if its below 200 ohms and check all circuits are RCD protected by one means or another.

 

[David Prosser]

Why is OP asking on here if he is a qualified electrician including 2391 ? The ability to identify an earthing system is a fairly basic skill that it would be impossible to pass 2391 without.