System type? (with pic)

[Cartboy52]

What system type is this?

The earth comes from a pole in the field into the house via the thin wire indicated. The wire goes down the pole into the ground.

Is this a TT supply? I'm not sure, as the earth is supplied by the distributer, not the customer (ie, does it need a 100mA RCD?).

Thanks

 

[Spark123]

If the earth is supplied via the distributor then it is more than likely a TN system, TN-S or TN-CS. What is the Ze?
Can you post a photo of the service head / meter / CU area?

 

[baz1968]

If the Ze is above 0.8 ohms then it's TT

 

[Spark123]

How do you arrive at that?

 

[Adam_151]

Looks like 11kv to me

 

[baz1968]

How do you arrive at that?

From the OSG

Maximum value of earth fault loop impedance outside consumers installation, TN-S = 0.8 ohms. Anything above that i would treat as TT.

 

[baz1968]

Looks like 11kv to me

How do you arrive at that?

 

[FingRinal]

A Ze of greater than 0.8ohms could mean anything at all. It could mean that the TN earth has a bad connection or a high resistance and the distributor needs to invetigate.

 

[GaryMo]

If the Ze is above 0.8 ohms then it's TT

Or it could be a TN-S or TNC-S with a poor earth connection.
Don't rely on figures alone when surveying earthing arrangements / system type.

 

[Click-Sure]

Any chance of a pic of the incomer?

 

[ricicle]

Looks like 11kv to me

How do you arrive at that?

The HV with a pole mounted transformer to 415/240V is 11Kv.Higher voltages are not normally stepped down to this voltage - 11Kv is the norm for rural overhead distribution.
It may be 11kv 3 wire for three phase secondary or 11kv 2 wire for a single phase secondary.

 

[Spark123]

If it is the same as around here, with a 415v/240v the wires will be arranged vertically whereas the higher voltages (MV?) the wires will be arranged horizontally.

 

[Cartboy52]

Any chance of a pic of the incomer?

Here -

I know the rest of the install is a mess and that is going to be sorted.

Just wanted to know if its TT or not - I don't think it is, but am not sure!

The earth wire is the black one below the meter and incommer.

 

[Spark123]

Where does the black wire go when it leaves the cupboard?

 

[Cartboy52]

Where does the black wire go when it leaves the cupboard?

It runs along the exterior wall and then goes straight to the pole - no joints or anything.