Another earthing query

[cambria]

At an installation today with three core 3 phase cable comimg in and the armour went into a connector providing the neutral (old photos were available from when work was done so could see this in DNOs box). 3 phases and neutral passed into the main DB but no MET. From the main DB the earth strip has two 35mm (approx) insulated earth cables going into concrete floor I cant find the other ends.
This is a caravan site and the three sub mains fed by SWA do have earth spikes as they have to be TT. Would you think the two 35mm earth cables in the main DB will go off to other earth spikes somewhere or what ?

 

[nickblake]

At an installation today with three core 3 phase cable comimg in and the armour went into a connector providing the neutral (old photos were available from when work was done so could see this in DNOs box). 3 phases and neutral passed into the main DB but no MET. From the main DB the earth strip has two 35mm (approx) insulated earth cables going into concrete floor I cant find the other ends.
This is a caravan site and the three sub mains fed by SWA do have earth spikes as they have to be TT. Would you think the two 35mm earth cables in the main DB will go off to other earth spikes somewhere or what ?

Under no circumstances should the armour be used as a neutral are you sure ,

 

[cambria]

Yep can see it clearly on the picture armour is stripped back and twisted into a connector black cable then coming off this into N bar on DB. Some old cable lying around as well which is only 3 core armoured and this is a 3 phase supply. Could they be using the armour as the N of the supply and no earth as this needs to be a TT installation anyway ?

 

[cambria]

By the way were talking heavy duty cable here so once the armour is twisted together its quite big

 

[johnboy6083]

in the new waveform cables, the copper armour is the neutral conductor, (TNC-S). ive seen it installed.

 

[nickblake]

is it armour or concentric , loads of black wires , if thats the case then it would be a tncs and the 35mm earths are the earths to the sub mains . pic shows single phase

 

[cambria]

Looks like copper armour

 

[cambria]

Would it be classed as TNC S at the origin as there is no earth would have thought TT. The 35mm earths dont go to the sub mains they each have their own rod so dont know where they go

 

[cambria]

Dothe DNOs ever provide an earth using 35mm yell/green ? Womder if they could be incoming from DNO rather than outgoing

 

[SEC-Tom]

The inner core is the Line, Blue Neutral clearly, the clean copper is then twisted together and used as the earth.

 

[the_mouse]

This is waveform cable, the main conductors are SAC ( solid aluminium conductors) the bare copper wires are CNE (combined neutral and earth)
The bare wires are applied in waveform which makes them aprox 16% longer than the main conductors, the outer sheath can be removed the copper wires pulled to one side to allow access to conductors so that they can be jointed live!!


Sent from my iPhone using Tapatalk

 

[mogga]

from the description it SOUNDS like Split concentric ( although Iv not seen 3ph concentric) it would be good if you could post the Photies here and might have a better guess

 

[cambria]

I can confirm that this is a 3 core waveform cable with 3 solida aluminium cores for the 3 phases and copper armour connected to the neutral. The 4 cables RYB and Black are then fed to the main DB but no earth. It brings me back to what the two 35mm earth cables are on the MET I wonder if they could be going to earth spikes somewhere which I cant find. Presumably this whole installation is therefore TT