Converting to a TT system... possibly

[chris day]

1.25ohm external earth fault loop impedance on TN-S supply to building

Supply authority stated our only option is a TT conversion as they will not covert to PME.

What would be my best course of action when converting to a TT as the building is quite old and i do not want a 100ma main switch for diversity reasons and nuisance tripping, so Would it be suitable to convert to TT and have all final circuits in a RCBO with a board charge?

 

[Nigel]

Lower than your imaginary 0.85 ze scenario you have just given

So we have a problem then don’t we?

How do we make it right?

Ps - I never brought the 0.85 into this thread.

 

[Ian1981]

So we have a problem then don’t we?

How do we make it right?

Ps - I never brought the 0.85 into this thread.

Better read through your posts, pretty sure you have posted an imaginary scenario of having to install a 300 amp distribution circuit with a ze of 0.85 ohms.

 

[Nigel]

Oh, resorting to RCD protection now are we? Sloppy, very sloppy.

You have limited options when you are dictated by a high Ze.

Rhe other options are silly so RCD protection makes perfect sense finacially and to meet BS7671.

 

[Nigel]

Better read through your posts, pretty sure you have posted an imaginary scenario of having to install a 300 amp distribution circuit with a ze of 0.85 ohms.

My point is that you stated that not meeting maz permitted Zs values was grounds enough to go back to the DNO.

I am just pointing out that that is rubbish.

 

[sparksburnout]

My point is that you stated that not meeting maz permitted Zs values was grounds enough to go back to the DNO.

I am just pointing out that that is rubbish.

Can I just ask, why do you have such an aggressive and condescending attitude towards other members who might have a differing opinion to yours? It seems like it is a bit of a recurring theme, to be frank.

 

[Nigel]

Can I just ask, why do you have such an aggressive and condescending attitude towards other members who might have a differing opinion to yours? It seems like it is a bit of a recurring theme, to be frank.

Apologies I thought we were just having a discussion.

 

[westward10]

These maximum values of Ze for TN systems are not carved in stone and I agree with Essex you work with what you have. You have two choices work with the existing system or put your own TT system in place but in both cases you rely on suitable rcds for fault protection. I would be constantly checking the Ze on the existing system to see if it falters and check any neighbouring premises for comparison.

 

[sparksburnout]

Apologies I thought we were just having a discussion.

It was a discussion, but this does not mean that you have to resort to inferring that other members on here are unprofessional, negligent or incompetent, as some of your comments seem to?

 

[Nigel]

It was a discussion, but this does not mean that you have to resort to inferring that other members on here are unprofessional, negligent or incompetent, as some of your comments seem to?

I have never stated anything of the sort. I think I recall you were the one calling names and questioning proffesionalism.

But I am a big boy. If I am wrong I will take it and learn from it.

Anyway. Back to the thread.

The DNO will not look into the high Ze. What would you do?

 

[PEG]

Put a rod in,as long as this thread...that'll get the Ze sorted...

 

[The Ghost]

Well in bear in mind, I am just stating my answer to your questions. Just for consideration. I accept there are differing ways of dealing with it. Just chewing the fat really.

 

[sparksburnout]

I have never stated anything of the sort. I think I recall you were the one calling names and questioning proffesionalism.

But I am a big boy. If I am wrong I will take it and learn from it.

Anyway. Back to the thread.

The DNO will not look into the high Ze. What would you do?

Professionalism. It's just got one "f".

 

[Nigel]

Professionalism. It's just got one "f".

Thank you.

What would you do in the ops situation to solve this issue?

 

[DPG]

Thank you.

What would you do in the ops situation to solve this issue?

He would usually make a derogatory comment about landlords
No offence intended Burnsy!

 

[sparksburnout]

Thank you.

What would you do in the ops situation to solve this issue?

Read the post, I have already said what should be done.