Maximum Ze value for TNS and TNCS System

[telectrix]

haha, why are the keys smaller than my fingers. quite often get the next one to the one i want. same thing happened when i got married. got the ex instead of her younger sister .

 

[Fox]

I made that same mistake!

 

[telectrix]

so you got the rottweiler instead of the vixen.

 

[Engineer54]

it's also a fact that while TN-S sheath is earthed at the sunstation ( apart from contact with the ground) a TNC-S system has multiple earthing points along the length of the supply cable (protective multiple earthing, PME) and that will reduce the Ze as well.

In theory, the lead sheath of PILC cables should never come in direct contact with the ground there was a insulating/bedding material between the old network wave line armour and the lead sheath. It is generally the breakdown of that insulating material allowing corrosive soil types to degrade/corrode the lead sheathing. Best ask Tony what the make-up was of those older PILC Waveline cables were, he has far more experience with them than i!!

Like the PME distribution cables, the TN-S cables would gain supplementary earthing from installations via bonding cables and connections to steel frame buildings and the like. One reason why they used to rod at TN-S service heads during the 50's. But as you rightly say PME cables will also (in theory anyway) have it's PEN conductor physically connected to earth at several points along it's length.

 

[dave1064]

Cheers guys. I know it wont come up but was just curiousity. That was the only explanation I could give. Just thought there might have been more to it.

 

[Outspoken]

earthed at the sunstation

But Tel, surely that is only for Solar Installations

 

[telectrix]

be a bloody long and expensive cable to earth the sun. would need to have a high operating temperature.

 

[Outspoken]

be a bloody long and expensive cable to earth the sun. would need to have a high operating temperature.

I think you would be struggling even with Pyro!!

 

[trev]

be a bloody long and expensive cable to earth the sun. would need to have a high operating temperature.

You could have it disconnected during the day time.

 

[Outspoken]

You could have it disconnected during the day time.

So that would mean the Australians would not have an Earth-Sun link during their day...Oh that would grate, they would moan like old dears!!

 

[telectrix]

You could have it disconnected during the day time.

sheer class.

 

[Darkwood]

As far as I know the values we are given for max or requirements for the DNO to comply to and if you are designing an install that doesn't yet exist you need a set max figure to base your design calculations on, the difference is as already mentioned as its expected a TNCS can achieve a better reading than a TNS as it has multiple earth points along its length.

 

[PEG]

The power of the sun is known,and it's 93,000,000 miles away,so what size copper cable to get disconnection in 5 secs?...and if it has an incomer,is the Lord DNO? Who's gonner cut THOSE seals? :yes:

 

[Darkwood]

My question is; Is the sun Inductive or resistive :ciappa:

 

[Outspoken]

My question is; Is the sun Inductive or resistive :ciappa:

Convective!